• Categories
• Modelo OSI
• Controlador de interfaz de red
• Red de computadoras
• Protocolos de Internet
• Redes

Citation preview

REDES INDUSTRIALES. ING. ALFONSO PEREZ GARCIA. INSTITUTO TECNLOGICO DE SAN LUIS POTOSI.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

INDICE

2 DE 133

INDICE.

PROGRAMA Prácticas. BIBLIOGRAFIA. UNIDAD 1 MODELO OSI

6 7 7 9

1.1 El modelo OSI. Modelo OSI

9 9

Historia Modelo de referencia OSI Capa Física (Capa 1) Codificación de la señal Topología y medios compartidos Equipos adicionales Capa de enlace de datos (Capa 2) Capa de red (Capa 3) Capa de transporte (Capa 4) Capa de sesión (Capa 5) Capa de presentación (Capa 6) Capa de aplicación (Capa 7) Unidades de datos Transmisión de los datos Formato de los datos Operaciones sobre los datos Bloqueo y desbloqueo Concatenación y separación

9 10 10 11 11 11 12 12 12 13 13 14 14 16 17 18 18 18

Véase también Enlaces externos 1.2 Su relación con las redes industriales Red industrial

18 18 18 19

Enlaces externos

23

2.1 Los estandares RS232, IEEE-488 y RS485 RS-232

24 24

INTRODUCCIÓN LA TECNOLOGÍA DE BUSES DE CAMPO ALGUNOS TIPOS DE BUS CLASIFICACION DE LAS REDES INDUSTRIALES. COMPONENTES DE LAS REDES INDUSTRIALES. TOPOLOGIA DE REDES INDUSTRIALES BENEFICIOS DE UNA RED INDUSTRIAL REDES INDUSTRIALES CON PLC SOLUCIONES CON ETHERNET CONCLUSION

UNIDAD 2 LAYERS FISICOS

24

Scope of the standard History Limitations of the standard Role in modern personal computers Standard details Conventions RTS/CTS handshaking 3-wire and 5-wire RS-232 ING. ALFONSO PEREZ GARCIA

19 19 20 21 21 22 22 22 22 23

24 24 25 26 26 33 33 33

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

INDICE

3 DE 133

Seldom used features Signal rate selection Loopback testing Timing signals Secondary channel Related standards

33 34 34 34 34 35

See also References External links

36 37 37

EIA-485 Waveform example References See also External links

38 40 42 42 42

Interface Converter RS232 to RS485 cable pinout IEEE-488 History Applications Signals Connectors

43 48 50 50 51 53

See also References External links 2.2 El lazo de corriente 4-20 Ma y HART HART Protocol Analog/digital mode Multidrop mode Packet Structure

53 53 53 55 55 56 56 56

External links

58

UNIDAD 3 FIELDBUS

59

3.1 INTRODUCCION. 59 ANALISIS DEL ESTADO DEL ARTE DE LOS BUSES DE CAMPO APLICADOS AL CONTROL DE PROCESOS INDUSTRIALES 59 RESUMEN 1. INTRODUCCIÓN 2. VENTAJAS DE LOS BUSES DE CAMPO 3. BUSES DE CAMPO EXISTENTES 4. ALGUNOS BUSES ESTANDARIZADOS 5. LA GUERRA DE LOS BUSES. 6. CONCLUSIONES BIBLIOGRAFIA

59 59 60 62 63 70 71 71

3.2 ESPECIFICACION. 3.3 APLICACIONES.

73 73

4.1 INTRODUCCION. Cableado y terminaciones Conectores Estructura Tipos de nodos Modos de sincronización Codificación Trama del mensaje

74 74 74 74 75 75 76 76

UNIDAD 4 BITBUS

ING. ALFONSO PEREZ GARCIA

74

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

INDICE

4 DE 133

Flag Dirección esclavo Control Información CRC

76 76 78 79 79

Trama del campo de información Longitud de información Tipo de mensaje (MT) Fuente de la orden (SE) Destino de la orden (DE) Pista (TR) 4 bits reservados Dirección esclavo Codificación de tareas Tareas usuario/Errores Datos

79 79 79 80 80 80 80 80 81 81

Registros de estado y contadores de secuencia Bibliografía

What is BITBUS?

81 83

84

What is the History of BITBUS? What are the Features of the iDCX 51 real time operating system? Can I still get BITBUS software? Can I still get BITBUS hardware? Can I still get BITBUS documentation?

BITBUS Basics

79

84 85 85 85 86

87

4.2 ESPECIFICACION. 4.3 APLICACIONES.

97 97

5.1 INTRODUCCION. AS-interface

98 98

UNIDAD 5 ASi

Características principales Enlaces externos

AS-Interface

98 98 99

99

External links 5.2 ESPECIFICACION. 5.3 APLICACIONES.

102 103 103

6.1 INTRODUCCION. Controller Area Network

104 104

See also References External links 6.2 ESPECIFICACION. 6.3 APLICACIONES.

115 115 115 117 117

7.1 INTRODUCCION DeviceNet

118 118

UNIDAD 6 CAN

Origins Applications CAN Network Testing Technology

UNIDAD 7 DEVICENET History ING. ALFONSO PEREZ GARCIA

104 104 104 104 105

118 118 INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

INDICE

5 DE 133

Technical Snapshot Architecture Conformance Test Sources

118 119 120 122

7.2 ESPECIFICACION. 7.3 APLICACIONES.

124 124

8.1 INTRODUCCION. Profibus Véase también Enlaces externos Profibus

125 125 125 125 126

UNIDAD 8 PROFIBUS

125

From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/Profibus" Origin Use Technology Standardization Organization

126 126 126 126 127 129 129

References External links 8.2 ESPECIFICACION. 8.3 APLICACIONES.

129 129 130 130

UNIDAD 9 ETHERNET

131

9.1 INTRODUCCION. PROFINET Technology PROFINET CBA PROFINET IO Organization Weblinks

9.2 ESPECIFICACION. 9.3 APLICACIONES.

ING. ALFONSO PEREZ GARCIA

131 131 131 131 131 132 132

133 133

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

PROGRAMA

6 DE 133

PROGRAMA S.E.P. DIRECCIÓN GENERAL DE INSTITUTOS TECNOLÓGICOS S.E.l.T 1. IDENTIFICACION DEL PROGRAMA DESARROLLADO POR UNIDADES DE APRENDIZAJE. NOMBRE DE LA ASIGNATURA: NIVEL: CARRERA: CLAVE:

NUMER O 1

TEMA MODELO OSI

2

LAYERS FISICOS

3

FIELDBUS

4

BITBUS

5

ASi

6

CAN

7

DEVICENET

8

PROFIBUS

9

ETHERNET

ING. ALFONSO PEREZ GARCIA

REDES INDUSTRIALES (3-2-8). LICENCIATURA. INGENIERIA ELECTRONICA. ECM 0705

SUBTEMAS: 1.1 El modelo OSI. 1.2 Su relación con las redes industriales 2.1 Los estandares RS232, RS488 y RS485 2.2 El lazo de corriente 420 Ma y HART 3.1 INTRODUCCION. 3.2 ESPECIFICACION. 4.1 INTRODUCCION. 4.2 ESPECIFICACION. 5.1 INTRODUCCION. 5.2 ESPECIFICACION. 6.1 INTRODUCCION. 6.2 ESPECIFICACION. 7.1 INTRODUCCION 7.2 ESPECIFICACION. 8.1 INTRODUCCION. 8.2 ESPECIFICACION. 9.1 INTRODUCCION. 9.2 ESPECIFICACION.

DURACIO EVAL. N 1 100% SEMANAS EE 1 100% SEMANAS EE

3.3 APLICACIONES. 4.3 APLICACIONES. 5.3 APLICACIONES. 6.3 APLICACIONES. 7.3 APLICACIONES. 8.3 APLICACIONES. 9.3 APLICACIONES.

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

2 SEMANAS 2 SEMANA 2 SEMANAS 2 SEMANAS 2 SEMANA 2 SEMANA 2 SEMANA

100% EE 100% EE 100% EE 100% EE 100% EE 100% EE 100% EE

PROGRAMA

7 DE 133

Prácticas. NUMERO DE PRACTICA. 1 2 3

DESCRIPCION (TEMA).

UNIDAD.

Red simple con protocolo HART Red simple de actuadores y sensores digitales con ASi. Red simple con protocolo Ethernet.

2 5 9

BIBLIOGRAFIA. AUTOR

TITULO Practical Industrial Data Networks: Design, Installation and Troubleshooting (IDC Technology (Paperback)) (Paperback)

1 Steve Mackay, Edwin Wright, Deon Reynders, John Park 2 Franco Davoli, Sergio Palazzo, Distributed Cooperative Laboratories: Networking, Sandro Zappatore Instrumentation, and Measurements (Signals and Communication Technology) 3 N. P. Mahalik Fieldbus Technology: Industrial Network Standards for Real-Time Distributed Control (Hardcover) NOMBRE HOW STUFF WORKS ESNIPS PAGINA PROFE FAIRCHILD SEMICONDUCTORS B&B ELECTRONICS.

DIRECCION WWW.HOWSTUFFWORKS.COM DEL WWW.ESNIPS.COM/WEB/REDESINDUSTRIA LES WWW.FAIRCHILDSEMI.COM

ING. ALFONSO PEREZ GARCIA

WWW.BB-ELEC.COM WWW.HARTCOMM.ORG WWW.FIELBUS.ORG

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

EDITORIAL

Newnes (July 2003) Springer; 1 edition (April 5, 2006) Springer; 1 edition (October 19, 2005) TEMAS

TODOS TODOS OPTOACOPLADORES RS232, RS488 Y RS485 HART PROTOCOL FIELDBUS ORGANIZATION

PROGRAMA

ING. ALFONSO PEREZ GARCIA

8 DE 133

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

9 DE 133

UNIDAD 1 MODELO OSI 1.1 El modelo OSI. Modelo OSI

De Wikipedia, la enciclopedia libre

El modelo de referencia de Interconexión de Sistemas Abiertos (OSI, Open System Interconnection) lanzado en 1984 fue el modelo de red descriptivo creado por ISO. Historia

A principios de la década de 1980 el desarrollo de redes sucedió con desorden en muchos sentidos. Se produjo un enorme crecimiento en la cantidad y el tamaño de las redes. A medida que las empresas tomaron conciencia de las ventajas de usar tecnología de networking, las redes se agregaban o expandían a casi la misma velocidad a la que se introducían las nuevas tecnologías de red. Para mediados de la década de 1980, estas empresas comenzaron a sufrir las consecuencias de la rápida expansión. De la misma forma en que las personas que no hablan un mismo idioma tienen dificultades para comunicarse, las redes que utilizaban diferentes especificaciones e implementaciones tenían dificultades para intercambiar información. El mismo problema surgía con las empresas que desarrollaban tecnologías de networking privadas o propietarias. "Propietario" significa que una sola empresa o un pequeño grupo de empresas controla todo uso de la tecnología. Las tecnologías de networking que respetaban reglas propietarias en forma estricta no podían comunicarse con tecnologías que usaban reglas propietarias diferentes. Para enfrentar el problema de incompatibilidad de redes, la Organización Internacional para la Estandarización (ISO) investigó modelos de networking como la red de Digital Equipment Corporation (DECnet), la Arquitectura de Sistemas de Red (SNA) y TCP/IP a fin de encontrar un conjunto de reglas aplicables de forma general a todas las redes. Con base en esta investigación, la ISO desarrolló un modelo de red que ayuda a los fabricantes a crear redes que sean compatibles con otras redes.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

10 DE 133

Modelo de referencia OSI

Siguiendo el esquema de este modelo se crearon numerosos protocolos, por ejemplo X.25, que durante muchos años ocuparon el centro de la escena de las comunicaciones informáticas. El advenimiento de protocolos más flexibles donde las capas no están tan demarcadas y la correspondencia con los niveles no era tan clara puso a este esquema en un segundo plano. Sin embargo sigue siendo muy usado en la enseñanza como una manera de mostrar como puede estructurarse una "pila" de protocolos de comunicaciones (sin importar su poca correspondencia con la realidad). El modelo en sí mismo no puede ser considerado una arquitectura, ya que no especifica el protocolo que debe ser usado en cada capa, sino que suele hablarse de modelo de referencia. Este modelo está dividido en siete capas: Capa Física (Capa 1)

Artículo principal: Nivel físico

La Capa Física del modelo de referencia OSI es la que se encarga de las conexiones físicas de la computadora hacia la red, tanto en lo que se refiere al medio físico (medios guiados: cable coaxial, cable de par trenzado, fibra óptica y otros tipos de cables; medios no guiados: radio, infrarrojos, microondas, láser y otras redes inalámbricas); características del medio (p.e. tipo de cable o calidad del mismo; tipo de conectores normalizados o en su caso tipo de antena; etc.) y la forma en la que se transmite la información (codificación de señal, niveles de tensión/intensidad de corriente eléctrica, modulación, tasa binaria, etc.) Es la encargada de transmitir los bits de información a través del medio utilizado para la transmisión. Se ocupa de las propiedades físicas y características eléctricas de los diversos componentes; de la velocidad de transmisión, si ésta es uni o bidireccional (símplex, dúplex o full-dúplex). También de aspectos mecánicos de las conexiones y terminales, incluyendo la interpretación de las señales eléctricas/electromagnéticas. Se encarga de transformar una trama de datos proveniente del nivel de enlace en una señal adecuada al medio físico utilizado en la transmisión. Estos impulsos pueden ser eléctricos (transmisión por cable) o electromagnéticos (transmisión sin cables). Estos últimos, dependiendo de la frecuencia / longitud de onda de la señal pueden ser ópticos, de micro-ondas o de radio. Cuando actúa en modo recepción el trabajo es inverso; se encarga de transformar la señal transmitida en tramas de datos binarios que serán entregados al nivel de enlace. Sus principales funciones se pueden resumir como: •

Definir el medio o medios físicos por los que va a viajar la comunicación: cable de pares trenzados (o no, como en RS232/EIA232), coaxial, guías de onda, aire, fibra óptica.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI •

• • • • •

11 DE 133

Definir las características materiales (componentes y conectores mecánicos) y eléctricas (niveles de tensión) que se van a usar en la transmisión de los datos por los medios físicos. Definir las características funcionales de la interfaz (establecimiento, mantenimiento y liberación del enlace físico). Transmitir el flujo de bits a través del medio. Manejar las señales eléctricas/electromagnéticas Especificar cables, conectores y componentes de interfaz con el medio de transmisión, polos en un enchufe, etc. Garantizar la conexión (aunque no la fiabilidad de ésta).

Codificación de la señal

El nivel físico recibe una trama binaria que debe convertir a una señal eléctrica, electromagnética u otra dependiendo del medio, de tal forma que a pesar de la degradación que pueda sufrir en el medio de transmisión vuelva a ser interpretable correctamente en el receptor. En el caso más sencillo el medio es directamente digital, como en el caso de las fibras ópticas, dado que por ellas se transmiten pulsos de luz. Cuando el medio no es digital hay que codificar la señal, en los casos más sencillos la codificación puede ser por pulsos de tensión (PCM o Pulse Code Modulatión) (por ejemplo 5 V para los "unos" y 0 V para los "ceros"), es lo que se llaman codificación unipolar RZ. Otros medios se codifican mediante presencia o ausencia de corriente. En general estas codificaciones son muy simples y no usan bien la capacidad de medio. Cuando se quiere sacar más partido al medio se usan técnicas de modulación más complejas, y suelen ser muy dependientes de las características del medio concreto. En los casos más complejos, como suelen ser las comunicaciones inalámbricas, se pueden dar modulaciones muy sofisticadas, este es el caso de los estándares WiFi, con técnicas de modulación complejas de espectro ensanchado Topología y medios compartidos

Indirectamente, el tipo de conexión que se haga en la capa física puede influir en el diseño de la capa de Enlace. Atendiendo al número de equipos que comparten un medio hay dos posibilidades: • Conexiones punto a punto: que se establecen entre dos equipos y que no admiten ser compartidas por terceros • Conexiones multipunto: en la que más de dos equipos pueden usar el medio. Así por ejemplo la fibra óptica no permite fácilmente conexiones multipunto (sin embargo, véase FDDI) y por el contrario las conexiones inalámbricas son inherentemente multipunto (sin embargo, véanse los enlaces infrarrojos). Hay topologías como el anillo, que permiten conectar muchas máquinas a partir de una serie de conexiones punto a punto. Equipos adicionales

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

12 DE 133

A la hora de diseñar una red hay equipos adicionales que pueden funcionar a nivel físico, se trata de los repetidores, en esencia se trata de equipos que amplifican la señal, pudiendo también regenerarla. En las redes Ethernet con la opción de cableado de par trenzado (la más común hoy por hoy) se emplean unos equipos de interconexión llamados concentradores (repetidores en las redes 10Base-2) más conocidos por su nombre en inglés (hubs) que convierten una topología física en estrella en un bus lógico y que actúan exclusivamente a nivel físico, a diferencia de los conmutadores (switches) que actúan a nivel de enlace. Capa de enlace de datos (Capa 2)

Artículo principal: Nivel de enlace de datos

Cualquier medio de transmisión debe ser capaz de proporcionar una transmisión sin errores, es decir, un tránsito de datos fiable a través de un enlace físico. Debe crear y reconocer los límites de las tramas, así como resolver los problemas derivados del deterioro, pérdida o duplicidad de las tramas. También puede incluir algún mecanismo de regulación del tráfico que evite la saturación de un receptor que sea más lento que el emisor. La capa de enlace de datos se ocupa del direccionamiento físico, de la topología de la red, del acceso a la red, de la notificación de errores, de la distribución ordenada de tramas y del control del flujo. Se hace un direccionamiento de los datos en la red ya sea en la distribución adecuada desde un emisor a un receptor, la notificación de errores, de la topología de la red de cualquier tipo. La tarjeta NIC (Network Interface Card, Tarjeta de Interfaz de Red en español o Tarjeta de Red) que se encarga que tengamos conexión, posee una dirección MAC (control de acceso al medio) y la LLC (control de enlace lógico). La PDU de la capa 2 es la trama. Capa de red (Capa 3)

Artículo principal: Nivel de red

El cometido de la capa de red es hacer que los datos lleguen desde el origen al destino, aún cuando ambos no estén conectados directamente. Los dispositivos que facilitan tal tarea se denominan en castellano encaminadores, aunque es más frecuente encontrar el nombre inglés routers y, en ocasiones enrutadores. Adicionalmente la capa de red debe gestionar la congestión de red, que es el fenómeno que se produce cuando una saturación de un nodo tira abajo toda la red (similar a un atasco en un cruce importante en una ciudad grande). La PDU de la capa 3 es el paquete. Los switch también pueden trabajar en esta capa dependiendo de la función que se le asigne. Capa de transporte (Capa 4)

Artículo principal: Nivel de transporte

Su función básica es aceptar los datos enviados por las capas superiores, dividirlos en pequeñas partes si es necesario, y pasarlos a la capa de red. En el caso del modelo OSI, también se asegura que lleguen correctamente al otro lado ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

13 DE 133

de la comunicación. Otra característica a destacar es que debe aislar a las capas superiores de las distintas posibles implementaciones de tecnologías de red en las capas inferiores, lo que la convierte en el corazón de la comunicación. En esta capa se proveen servicios de conexión para la capa de sesión que serán utilizados finalmente por los usuarios de la red al enviar y recibir paquetes. Estos servicios estarán asociados al tipo de comunicación empleada, la cual puede ser diferente según el requerimiento que se le haga a la capa de transporte. Por ejemplo, la comunicación puede ser manejada para que los paquetes sean entregados en el orden exacto en que se enviaron, asegurando una comunicación punto a punto libre de errores, o sin tener en cuenta el orden de envío. Una de las dos modalidades debe establecerse antes de comenzar la comunicación para que una sesión determinada envíe paquetes, y ése será el tipo de servicio brindado por la capa de transporte hasta que la sesión finalice. De la explicación del funcionamiento de esta capa se desprende que no está tan encadenada a capas inferiores como en el caso de las capas 1 a 3, sino que el servicio a prestar se determina cada vez que una sesión desea establecer una comunicación. Todo el servicio que presta la capa está gestionado por las cabeceras que agrega al paquete a transmitir. En resumen, podemos definir a la capa de transporte como: Capa encargada de efectuar el transporte de los datos (que se encuentran dentro del paquete) de la máquina origen a la destino, independizándolo del tipo de red física que se esté utilizando. La PDU de la capa 4 se llama Segmentos. Capa de sesión (Capa 5)

Artículo principal: Nivel de sesión

Esta capa Establece, gestiona y finaliza las conexiones entre usuarios (procesos o aplicaciones) finales. Ofrece varios servicios que son cruciales para la comunicación, como son: • Control de la sesión a establecer entre el emisor y el receptor (quién transmite, quién escucha y seguimiento de ésta). • Control de la concurrencia (que dos comunicaciones a la misma operación crítica no se efectúen al mismo tiempo). • Mantener puntos de verificación (checkpoints), que sirven para que, ante una interrupción de transmisión por cualquier causa, la misma se pueda reanudar desde el último punto de verificación en lugar de repetirla desde el principio. Por lo tanto, el servicio provisto por esta capa es la capacidad de asegurar que, dada una sesión establecida entre dos máquinas, la misma se pueda efectuar para las operaciones definidas de principio a fin, reanudándolas en caso de interrupción. En muchos casos, los servicios de la capa de sesión son parcialmente, o incluso, totalmente prescindibles. En conclusión esta capa es la que se encarga de mantener el enlace entre los dos computadores que estén trasmitiendo archivos. Capa de presentación (Capa 6)

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

14 DE 133

El objetivo de la capa de presentación es encargarse de la representación de la información, de manera que aunque distintos equipos puedan tener diferentes representaciones internas de caracteres (ASCII, Unicode, EBCDIC), números (littleendian tipo Intel, big-endian tipo Motorola), sonido o imágenes, los datos lleguen de manera reconocible. Esta capa es la primera en trabajar más el contenido de la comunicación que cómo se establece la misma. En ella se tratan aspectos tales como la semántica y la sintaxis de los datos transmitidos, ya que distintas computadoras pueden tener diferentes formas de manejarlas. Por lo tanto, podemos resumir definiendo a esta capa como la encargada de manejar las estructuras de datos abstractas y realizar las conversiones de representación de datos necesarias para la correcta interpretación de los mismos. Esta capa también permite cifrar los datos y comprimirlos. En pocas palabras es un traductor Capa de aplicación (Capa 7)

Ofrece a las aplicaciones(de usuario o no) la posibilidad de acceder a los servicios de las demás capas y define los protocolos que utilizan las aplicaciones para intercambiar datos, como correo electrónico (POP y SMTP), gestores de bases de datos y servidor de ficheros (FTP). Hay tantos protocolos como aplicaciones distintas y puesto que continuamente se desarrollan nuevas aplicaciones el número de protocolos crece sin parar. Cabe aclarar que el usuario normalmente no interactúa directamente con el nivel de aplicación. Suele interactuar con programas que a su vez interactúan con el nivel de aplicación pero ocultando la complejidad subyacente. Así por ejemplo un usuario no manda una petición "HTTP/1.0 GET index.html" para conseguir una página en html, ni lee directamente el código html/xml. Entre los protocolos (refiriéndose a protocolos genéricos, no a protocolos de la capa de aplicación de OSI) más conocidos destacan: HTTP (HyperText Transfer Protocol) el protocolo bajo la www FTP (File Transfer Protocol) ( FTAM, fuera de TCP/IP) transferencia de ficheros • SMTP (Simple Mail Transfer Protocol) (X.400 fuera de tcp/ip) envío y distribución de correo electrónico • POP (Post Office Protocol)/IMAP: reparto de correo al usuario final • SSH (Secure SHell) principalmente terminal remoto, aunque en realidad cifra casi cualquier tipo de transmisión. • Telnet otro terminal remoto, ha caído en desuso por su inseguridad intrínseca, ya que las claves viajan sin cifrar por la red. Hay otros protocolos de nivel de aplicación que facilitan el uso y administración de la red: • SNMP (Simple Network Management Protocol) • DNS (Domain Name System) • •

Unidades de datos

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

15 DE 133

El intercambio de información entre dos capas OSI consiste en que cada capa en el sistema fuente le agrega información de control a los datos, y cada capa en el sistema de destino analiza y remueve la información de control de los datos como sigue: Si un ordenador (host A) desea enviar datos a otro (host B), en primer término los datos deben empaquetarse a través de un proceso denominado encapsulamiento, es decir, a medida que los datos se desplazan a través de las capas del modelo OSI, reciben encabezados, información final y otros tipos de información.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

16 DE 133

N-PDU (Unidad de datos de protocolo) Es la información intercambiada entre entidades pares,es decir,dos entidades pertenecientes a la misma capa pero en dos sistemas diferentes, utilizando una conexión(N-1). Esta compuesta por: N-SDU (Unidad de datos del servicio) Son los datos que se necesitan la entidades(N) para realizar funciones del servicio pedido por la entidad(N+1). N-PCI (Información de control del protocolo) Información intercambiada entre entidades (N) utilizando una conexión (N1) para coordinar su operación conjunta. N-IDU (Unidad de datos del interface) Es la información transferida entre dos niveles adyacentes,es decir, dos capas contiguas. Esta compuesta por: N-ICI (Información de control del interface) Información intercambiada entre una entidad (N+1) y una entidad (N) para coordinar su operación conjunta. Datos de Interface-(N) Información transferida entre una entidad-(N+1) y una entidad-(N) y que normalmente coincide con la (N+1)-PDU. Transmisión de los datos

La capa de aplicación recibe el mensaje del usuario y le añade una cabecera constituyendo así la PDU de la capa de aplicación. La PDU se transfiere a la capa de aplicación del nodo destino, este elimina la cabecera y entrega el mensaje al usuario. Para ello ha sido necesario todo este proceso: 1-Ahora hay que entregar la PDU a la capa de presentación para ello hay que añadirla la correspondiente cabecera ICI y transformarla así en una IDU, la cual se transmite a dicha capa. 2-La capa de presentación recibe la IDU, le quita la cabecera y extrae la información, es decir, la SDU, a esta le añade su propia cabecera (PCI) constituyendo así la PDU de la capa de presentación. 3- Esta PDU es transferida a su vez a la capa de sesión mediante el mismo proceso, repitiéndose así para todas las capas. 4-Al llegar al nivel físico se envían los datos que son recibidos por la capa física del receptor. 5-Cada capa del receptor se ocupa de extraer la cabecera, que anteriormente había añadido su capa homóloga, interpretarla y entregar la PDU a la capa superior. 6-Finalmente llegará a la capa de aplicación la cual entregará el mensaje al usuario.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

17 DE 133

Formato de los datos

Estos datos reciben una serie de nombres y formatos específicos en función de la capa en la que se encuentren, debido a como se describió anteriormente la adhesión de una serie de encabezados e información final. Los formatos de información son los que muestra el gráfico:

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

18 DE 133

APDU: Unidad de datos en la capa de aplicación. PPDU: Unidad de datos en la capa de presentación. SPDU: Unidad de datos en la capa de sesión. TPDU:(segmento) Unidad de datos en la capa de transporte. Paquete: Unidad de datos en el nivel de red. Trama: Unidad de datos en la capa de enlace. Bits: Unidad de datos en la capa física. Operaciones sobre los datos

En determinadas situaciones es necesario realizar una serie de operaciones sobre las PDU para facilitar su transporte, bien debido a que son demasiado grandes o bien porque son demasiado pequeñas y estaríamos desaprovechando la capacidad del enlace. Segmentación y reensamblaje [editar]

Hace corresponder a una (N)-SDU sobre varias (N)-PDU. El reensamblaje hace corresponder a varias (N)-PDUs en una (N)-SDU. Bloqueo y desbloqueo

El bloqueo hace corresponder varias (N)-SDUs en una (N)-PDU. El desbloqueo identifica varias (N)-SDUs que están contenidas en una (N)-PDU. Concatenación y separación

La concatenación es una función-(N) que realiza el nivel-(N) y que hace corresponder varias (N)-PDUs en una sola (N-1)-SDU. La separación identifica varias (N)-PDUs que están contenidas en una sola (N-1)-SDU. Véase también • Familia de protocolos de Internet Enlaces externos • Estándar ISO 7498-1:1994 (formato ZIP) • Cybertelecom — Layered Model of Regulation • OSI Reference Model — The ISO Model of Architecture for Open Systems Interconnection, Hubert Zimmermann, IEEE Transactions on Communications, vol. 28, no. 4, April 1980, pp. 425 - 432. • Introduction to Data Communications • Internetworking Basics • MODELO DE REFERENCIA OSI - Interconexión de Sistemas Abiertos Cátedra Sistemas de Comunicaciones. Universidad Tecnológica Nacional, Facultad Regional Mendoza, Argentina. 1.2 Su relación con las redes industriales ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

19 DE 133

Red industrial De Wikipedia, la enciclopedia libre Obtenido de "http://es.wikipedia.org/wiki/Red_industrial" INTRODUCCIÓN

Las redes de comunicaciones industriales deben su origen a la fundación FieldBus (Redes de campo). La fundación FieldBus, desarrollo un nuevo protocolo de comunicación, para la medición y control de procesos donde todos los instrumentos puedan comunicarse en una misma plataforma. Las comunicaciones entre los instrumentos de proceso y el sistema de control se basan principalmente en señales analógicas (neumáticas de 3 a 15 psi en las válvulas de control y electrónicas de 4 a 20 mA cc). Pero ya existen instrumentos digitales capaces de manejar gran cantidad de datos y guardarlos históricamente; su precisión es diez veces mayor que la de la señal típica de 4-20 mA cc. En vez de transmitir cada variable por un par de hilos, transmiten secuencialmente las variables por medio de un cable de comunicaciones llamado bus. La tecnología fieldbus (bus de campo) es un protocolo de comunicaciones digital de alta velocidad que esta creada para remplazar la clásica señal de 4-20 mA que aún se utiliza en muchos de los sistemas DCS (Sistema de Control Distribuido) y PLC (Controladores Lógicos Programables), instrumentos de medida y transmisión y válvulas de control. La arquitectura fieldbus conecta estos instrumentos con computadores que se usan en diferentes niveles de coordinación y dirección de la planta. Muchos de los protocolos patentados para dichas aplicaciones tiene una limitante y es que el fabricante no permite al usuario final la interoperabilidad de instrumentos, es decir, no es posible intercambiar los instrumentos de un fabricante por otro similar. Es claro que estas tecnologías cerradas tienden a desaparecer ya que actualmente es necesaria la interoperabilidad de sistemas y aparatos y así tener la capacidad de manejar sistemas abiertos y estandarizados. Con el mejoramiento de los protocolos de comunicación es ahora posible reducir el tiempo necesitado para la transferencia de datos, asegurando la misma, garantizando el tiempo de sincronización y el tiempo real de respuesta determinística en algunas aplicaciones. LA TECNOLOGÍA DE BUSES DE CAMPO

Físicamente podemos considerar a un bus como un conjunto de conductores conectando conjuntamente más circuitos para permitir el intercambio de datos. Contrario a una conexión punto a punto donde solo dos dispositivos intercambian información, un bus consta normalmente de un número de usuarios superior, además que generalmente un bus transmite datos en modo serial, a excepción de algún protocolo de bus particular como SCSI, o IEEE-488 utilizado para interconexión de instrumentos de medición, que no es el caso de los buses tratados como buses de campo. Para una transmisión serial es suficiente un número de cables muy limitado, generalmente son suficientes dos o tres conductores y la debida protección contra las perturbaciones externas para permitir su tendido en ambientes de ruido industrial. ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

20 DE 133

Ventajas de un bus de campo

- El intercambio puede llevar a cabo por medio de un mecanismo estándar. Flexibilidad de extensión. - Conexión de módulos diferentes en una misma línea. Posibilidad de conexión de dispositivos de diferentes procedencias. - Distancias operativas superiores al cableado tradicional. - Reducción masiva de cables y costo asociado. - Simplificación de la puesta en servicio. Desventajas de un bus de campo

- Necesidad de conocimientos superiores. - Inversión de instrumentación y accesorios de diagnóstico. - Costos globales inicialmente superiores. Procesos de comunicación por medio de bus

El modo más sencillo de comunicación con el bus es el sondeo cliente/servidor. Más eficiente pero también más costoso es el Token bus ( IEEE 802.4), desde el punto de vista físico tenemos un bus lineal, desde el punto de vista lógico un token ring. El procedimiento token passing es una combinación entre cliente/servidor y token bus. Todo servidor inteligente puede ser en algún momento servidor. ALGUNOS TIPOS DE BUS

La mayoría de los buses trabajan en el nivel 1 con interfaz RS 485. ASI (Actuator Sensor Interface)

Es el bus más inmediato en el nivel de campo y más sencillo de controlar, consiste en un bus cliente/servidor con un máximo de 31 participantes, transmite por paquetes de solo 4 bits de dato. Es muy veloz, con un ciclo de 5 ms aproximadamente. Alcanza distancias de máximo 100 m. BITBUS

Es el más difundido en todo el mundo, es cliente/servidor que admite como máximo 56 clientes, el paquete puede transmitir hasta 43 bytes de dato. PROFIBUS (PROcess FIeld BUS)

Es el estándar europeo en tecnología de buses, se encuentra jerárquicamente por encima de ASI y BITBUS, trabaja según procedimiento híbrido token passing, dispone de 31 participantes hasta un máximo de 127. Su paquete puede transmitir un máximo de 246 Bytes, y el ciclo para 31participantes es de aproximadamente 90 ms. Alcanza una distancia de hasta 22300 m.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

21 DE 133

FieldBus en OSI

En la arquitectura OSI, fieldbus ocupa los niveles 1 (Físico), 2 (Enlace de Datos) y 7 (Aplicación); teniendo en cuenta que este último no solo se encarga de la interfaz de usuario sino de aplicaciones especificas dependiendo de cada aplicación. CLASIFICACION DE LAS REDES INDUSTRIALES.

Si se clasifican las redes industriales en diferentes categorías basándose en la funcionalidad, se hará en: Buses Actuadores y Sensores

Inicialmente es usado un sensor y un bus actuador en conexión simple, dispositivos discretos con inteligencia limitada, como un foto sensor, un switch limitador o una válvula solenoide, controladores y consolas terminales. Buses de Campo y Dispositivos

Estas redes se distinguen por la forma como manejan el tamaño del mensaje y el tiempo de respuesta. En general estas redes conectan dispositivos inteligentes en una sola red distribuida.(Delta V de Emmerson) Estas redes ofrecen altos niveles de diagnóstico y capacidad de configuración, generalmente al nivel del poder de procesamiento de los dispositivos más inteligentes. Son las redes más sofisticadas que trabajan con control distribuido real entre dispositivos inteligentes, tal es el caso de FIELDBUS FOUNDATION. COMPONENTES DE LAS REDES INDUSTRIALES.

En grandes redes industriales un simple cable no es suficiente para conectar el conjunto de todos los nodos de la red. Deben definirse topologías y diseños de redes para proveer un aislamiento y conocer los requerimientos de funcionamiento. Bridge

Con un puente la conexión entre dos diferentes secciones de red, puede tener diferentes características eléctricas y protocolos; además puede enlazar dos redes diferentes. Repetidor

El repetidor o amplificador es un dispositivo que intensifica las señales eléctricas para que puedan viajar grandes distancias entre nodos. Con este dispositivo se pueden conectar un gran número de nodos a la red; además se pueden adaptar a diferentes medios físicos como cable coaxial o fibra óptica.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

22 DE 133

Gateway

Un gateway es similar a un puente ya que suministra interoperabilidad entre buses y diferentes tipos de protocolos y además las aplicaciones pueden comunicarse a través de él. Enrutadores

Es un switch "Enrutador" de paquetes de comunicación entre diferentes segmentos de red que definen la ruta. TOPOLOGIA DE REDES INDUSTRIALES

Los sistemas industriales usualmente consisten de dos o mas dispositivos, como un sistema industrial puede ser bastante grande debe considerarse la topología de la red; las topologías más comunes son: La Red Bus, Red Estrella y Red Híbrida BENEFICIOS DE UNA RED INDUSTRIAL

- Reducción de cableado (físicamente) - Dispositivos inteligentes (funcionalidad y ejecución) - Control distribuido (Flexibilidad) - Simplificación de cableado de las nuevas instalaciones - Reducción de costo en cableado y cajas de conexión Aplicable a todo tipo de sistema de manufactura - Incremento de la confiabilidad de los sistemas de producción - Optimización de los procesos existentes. REDES INDUSTRIALES CON PLC

Muchos sistemas están conformados por equipos de diferentes fabricantes y funcionan en diferentes niveles de automatización; además, a menudo se encuentran distanciados entre sí; pero sin embargo, se desea que trabajen en forma coordinada para un resultado satisfactorio del proceso. El objetivo principal es la comunicación totalmente integrada en el sistema. Al usuario, esto le reporta la máxima flexibilidad ya que también puede integrar sin problemas productos de otros fabricantes a través de las interfaces software estandarizadas. En los últimos años, las aplicaciones industriales basadas en comunicación digital se han incrementado haciendo posible la conexión de sensores, actuadores y equipos de control en una planta de procesamiento. De esta manera, la comunicación entre la sala de control y los instrumentos de campo se han convertido en realidad. La Comunicación digital debe integrar la información provista por los elementos de campo en el sistema de control de procesos. SOLUCIONES CON ETHERNET

Aunque los buses de campo continuarán dominando las redes industriales, las soluciones basadas en Ethernet se están utilizando cada vez más en el sector de las tecnologías de automatización, donde las secuencias de procesos y producción son controladas por un modelo cliente/servidor con controladores, PLC y sistemas ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 1 MODELO OSI

23 DE 133

ERP (Planificación de los recursos de la empresa), teniendo acceso a cada sensor que se conecta a la red. La implementación de una red efectiva y segura también requiere el uso de conectores apropiados, disponibles en una amplia variedad y para soluciones muy flexibles. Los Gateway son dispositivos de capa de transporte; en donde la capa de aplicación no necesariamente es software por lo general las aplicaciones son de audio (alarmas), vídeo (vigilancia), monitoreo y control (sensores), conversión análoga/digital y digital/analóga. Para la programación de gateway de alto nivel se utiliza el C++ y para la programación menos avanzada se hace con hojas de cálculo. Estos dispositivos pueden ser programados de tal forma que en caso de una emergencia o un simple cambio a otro proceso no se haga manualmente sino realmente automático. CONCLUSION

Hoy en día las tecnologías que triunfan en el mercado son aquellas que ofrecen las mejores ventajas y seguridad a los clientes, cada vez se está acabando con tecnologías cerradas; que en un mundo en proceso de globalización, es imposible que sobrevivan. A nivel industrial se está dando un gran cambio, ya que no solo se pretende trabajar con la especificidad de la instrumentación y el control automático, sino que existe la necesidad de mantener históricamente información de todos los procesos, además que esta información este también en tiempo real y que sirva para la toma de decisiones y se pueda así mejorar la calidad de los procesos. Las condiciones extremas a nivel industrial requieren de equipos capaces de soportar elevadas temperaturas, ruido excesivo, polvo, humedad y demás condiciones adversas; pero además requiere de personal capaz de ver globalmente el sistema de control y automatización industrial junto con el sistema de red digital de datos. Enlaces externos redes de comunicación industrial redes induatriales aplicaciones redes industruales con PLC

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

24 DE 133

UNIDAD 2 LAYERS FISICOS 2.1 Los estandares RS232, IEEE-488 y RS485 RS-232

From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/RS-232"

In telecommunications, RS-232 (Recommended Standard 232) is a standard for serial binary data signals connecting between a DTE (Data terminal equipment) and a DCE (Data Circuit-terminating Equipment). It is commonly used in computer serial ports. A similar ITU-T standard is V.24. Scope of the standard

The Electronic Industries Alliance (EIA) standard RS-232-C[1] as of 1969 defines: •

• • •

Electrical signal characteristics such as voltage levels, signaling rate, timing and slew-rate of signals, voltage withstand level, short-circuit behavior, maximum stray capacitance and cable length. Interface mechanical characteristics, pluggable connectors and pin identification. Functions of each circuit in the interface connector. Standard subsets of interface circuits for selected telecom applications.

The standard does not define such elements as • • • •

•

character encoding (for example, ASCII, Baudot or EBCDIC) the framing of characters in the data stream (bits per character, start/stop bits, parity) protocols for error detection or algorithms for data compression bit rates for transmission, although the standard says it is intended for bit rates lower than 20,000 bits per second. Many modern devices support speeds of 115,200 bps and above power supply to external devices.

Details of character format and transmission bit rate are controlled by the serial port hardware, often a single integrated circuit called a UART that converts data from parallel to serial form. A typical serial port includes specialized driver and receiver integrated circuits to convert between internal logic levels and RS-232 compatible signal levels. History

The original DTEs were electromechanical teletypewriters and the original DCEs were (usually) modems. When electronic terminals (smart and dumb) began to be used, they were often designed to be interchangeable with teletypes, and so ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

25 DE 133

supported RS-232. The C revision of the standard was issued in 1969 in part to accommodate the electrical characteristics of these devices. Since application to devices such as computers, printers, test instruments, and so on were not considered by the standard, designers implementing an RS-232 compatible interface on their equipment often interpreted the requirements idiosyncratically. Common problems were non-standard pin assignment of circuits on connectors, and incorrect or missing control signals. The lack of adherence to the standards produced a thriving industry of breakout boxes, patch boxes, test equipment, books, and other aids for the connection of disparate equipment. A common deviation from the standard was to drive the signals at a reduced voltage: the standard requires the transmitter to use +12V and -12V, but requires the receiver to distinguish voltages as low as +3V and -3V. Some manufacturers therefore built transmitters that supplied +5V and -5V and labeled them as "RS232 compatible." Later personal computers (and other devices) started to make use of the standard so that they could connect to existing equipment. For many years, an RS-232compatible port was a standard feature for serial communications, such as modem connections, on many computers. It remained in widespread use into the late 1990s. While it has largely been supplanted by other interface standards in computer products, it is still used to connect older designs of peripherals, industrial equipment (such as based on PLCs), and console ports, and special purpose equipment such as a cash drawer for a cash register. The standard has been renamed several times during its history as the sponsoring organization changed its name, and has been variously known as EIA RS 232, EIA 232, and most recently as TIA 232. The standard continues to be revised and updated by the EIA and since 1988 the Telecommunications Industry Association (TIA)[2]. Revision C was issued in a document dated August 1969. Revision D was issued in 1986. The current revision is TIA-232-F Interface Between Data Terminal Equipment and Data Circuit-Terminating Equipment Employing Serial Binary Data Interchange, issued in 1997. Changes since Revision C have been in timing and details intended to improve harmonization with the CCITT standard V.24, but equipment built to the current standard will interoperate with older versions. Limitations of the standard

Because the application of RS-232 has extended far beyond the original purpose of interconnecting a terminal with a modem, successor standards have been developed to address the limitations. Issues with the RS-232 standard include: •

• •

The large voltage swings and requirement for positive and negative supplies increases power consumption of the interface and complicates power supply design. The voltage swing requirement also limits the upper speed of a compatible interface. Single-ended signaling referred to a common signal ground limit the noise immunity and transmission distance. Multi-drop (meaning a connection between more than two devices) operation of an RS-232 compatible interface is not defined; while multi-drop

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

•

•

•

•

26 DE 133

"work-arounds" have been devised, they have limitations in speed and compatibility. Asymmetrical definitions of the two ends of the link make the assignment of the role of a newly developed device problematic; the designer must decide on either a DTE-like or DCE-like interface and which connector pin assignments to use. The handshaking and control lines of the interface are intended for the setup and takedown of a dial-up communication circuit; in particular, the use of handshake lines for flow control is not reliably implemented in many devices. No method for sending power to a device, while a small amount of current can be extracted from the DTR and RTS lines this can only be used for low power devices such as mice. While the standard recommends a connector and pinout, the connector is large by current standards.

Role in modern personal computers

PCI Express x1 card with one RS-232 port Main article: Serial port In the book PC 97 Hardware Design Guide[3], Microsoft deprecated support for the RS-232 compatible serial port of the original IBM PC design. Today, RS-232 is gradually being superseded in personal computers by USB for local communications. Compared with RS-232, USB is faster, has lower voltage levels, and has connectors that are simpler to connect and use. Both standards have software support in popular operating systems. USB is designed to make it easy for device drivers to communicate with hardware. However, there is no direct analog to the terminal programs used to let users communicate directly with serial ports. USB is more complex than the RS 232 standard because it includes a protocol for transferring data to devices. This requires more software to support the protocol used. RS 232 only standardizes the voltage of signals and the functions of the physical interface pins. Serial ports of personal computers are also often used to directly control various hardware devices, such as relays or lamps, since the control lines of the interface could be easily manipulated by software. This isn't feasible with USB which requires some form of receiver to decode the serial data. As an alternative, USB docking ports are available which can provide connectors for a keyboard, mouse, one or more serial ports, and one or more parallel ports. Corresponding device drivers are required for each USB-connected device to allow programs to access these USB-connected devices as if they were the original directly-connected peripherals. Devices that convert USB to RS 232 may not work with all software on all personal computers. Standard details ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

27 DE 133

In RS-232, data is sent as a time-series of bits. Both synchronous and asynchronous transmissions are supported by the standard. In addition to the data circuits, the standard defines a number of control circuits used to manage the connection between the DTE and DCE. Each data or control circuit only operates in one direction, that is, signaling from a DTE to the attached DCE or the reverse. Since transmit data and receive data are separate circuits, the interface can operate in a full duplex manner, supporting concurrent data flow in both directions. The standard does not define character framing within the data stream, or character encoding.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

28 DE 133

Voltage levels

Diagrammatic oscilloscope trace of voltage levels for ASCII "K" character (0x4b) with 1 start bit, 8 data bits, 1 stop bit Main article: Serial port The RS-232 standard defines the voltage levels that correspond to logical one and logical zero levels. Valid signals are plus or minus 3 to 15 volts. The range near zero volts is not a valid RS-232 level; logic one is defined as a negative voltage, the signal condition is called marking, and has the functional significance of OFF. Logic zero is positive, the signal condition is spacing, and has the function ON. The standard specifies a maximum open-circuit voltage of 25 volts; signal levels of ±5 V,±10 V,±12 V, and ±15 V are all commonly seen depending on the power supplies available within a device. RS-232 drivers and receivers must be able to withstand indefinite short circuit to ground or to any voltage level up to +/-25 volts. The slew rate, or how fast the signal changes between levels, is also controlled. Because the voltage levels are higher than logic levels typically used by integrated circuits, special intervening driver circuits are required to translate logic levels. These also protect the device's internal circuitry from short circuits or transients that may appear on the RS-232 interface, and provide sufficent current to comply with the slew rate requirements for data transmission. Because both ends of the RS-232 circuit depend on the ground pin being zero volts, problems will occur when connecting machinery and computers where the voltage between the ground pin on one end, and the ground pin on the other is not zero. This may also cause a hazardous ground loop. Connectors

RS-232 devices may be classified as Data Terminal Equipment (DTE) or Data Communications Equipment (DCE); this defines at each device which wires will be sending and receiving each signal. The standard recommended but did not make mandatory the D-subminiature 25 pin connector. In general, terminals have male connectors with DTE pin functions, and modems have female connectors with DCE pin functions. Other devices may have any combination of connector gender and pin definitions. Presence of a 25 pin D-sub connector does not necessarily indicate an RS-232C compliant interface. For example, on the original IBM PC, a male D-sub was an RS232C DTE port (with a non-standard current loop interface on reserved pins), but the female D-sub connector was used for a parallel Centronics printer port. Some personal computers put non-standard voltages or signals on their serial ports.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

29 DE 133

Female 9 pin plug The standard specifies 20 different signal connections. Since most devices use only a few signals, smaller connectors can be used. For example, the 9 pin DE-9 connector was used by most IBM-compatible PCs since the IBM PC AT, and has been standardized as TIA-574. More recently, modular connectors have been used. Most common are 8 pin RJ45 connectors. Standard EIA/TIA 561 specifies a pin assignment, but the "Yost Serial Device Wiring Standard" invented by Dave Yost is common on Unix computers and newer devices from Cisco Systems. Many devices don't use either of these standards. 10 pin RJ-50 connectors can be found on some devices as well. Digital Equipment Corporation defined their own DECconnect connection system which was based on the Modified Modular Jack connector. This is a 6 pin modular jack where the key is offset from the center position. As with the Yost standard, DECconnect uses a symmetrical pin layout which enables the direct connection between two DTEs. Another common connector is the DH10 header connector common on motherboards and add-in cards which is usually converted via a cable to the more standard 9 pin DE-9 connector (and frequently mounted on a free slot plate or other part of the housing).

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

30 DE 133

Pinouts (DTE relative)

The following table lists the commonly used RS-232 signals and common pin assignments DE-9 Cisc Signal Abbr DBEIA/TIA RJHirschman Alternate Dir. (TIAYost MMJ o RJType . 25 561 50 n RJ-45 s 574) 45 Common G Ground

–

7

5

4

4,5 6

3,4

4,5

4

Transmitt TxD ed Data

Out 2

3

6

3

8

2

3

3

2

5

6

9

5

6

5

DTR Out 20 4

3

2

7

1

2

-

1

7

5

6

7

-

Received RxD In Data Data Terminal Ready

Data Set DSR In Ready Request To Send Clear Send Carrier Detect

To

3

6

6

RTS

Out 4

7

8

1

4

-

1 (Aux only)

CTS

In

5

8

7

8

3

-

8 (Aux only)

DCD In

8

1

2

7

10 -

-

-

22 9

1

-

2

-

-

Ring RI Indicator

In

-

The signals are labeled from the standpoint of the DTE device; TD, DTR, and RTS are generated by the DTE and RD, DSR, CTS, DCD, and RI are generated by the DCE. The ground signal is a common return for the other connections; it appears on two pins in the Yost standard but is the same signal. Connection of pin 1 (protective ground) and pin 7 (signal reference ground) is a common practice but not recommended. Use of a common ground is one weakness of RS-232. If the two pieces of equipment are far enough apart or on separate power systems, the ground will degrade between them and communications will fail; this is a difficult condition to trace. Note that EIA/TIA 561 combines DSR and RI, and the Yost standard combines DSR and DCD.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

31 DE 133

Signals

Commonly-used signals are: Transmitted Data (TxD) Data sent from DTE to DCE. Received Data (RxD) Data sent from DCE to DTE. Request To Send (RTS) Asserted (set to 0) by DTE to prepare DCE to receive data. This may require action on the part of the DCE, e.g. transmitting a carrier or reversing the direction Clear To Send (CTS) Asserted by DCE to acknowledge RTS and allow DTE to transmit. Data Terminal Ready (DTR) Asserted by DTE to indicate that it is ready to be connected. If the DCE is a modem, this may "wake up" the modem, bringing it out of a power saving mode. This behaviour is seen quite often in modern PSTN and GSM modems. When this signal is de-asserted, the modem may return to its standby mode, immediately hanging up any calls in progress. Data Set Ready (DSR) Asserted by DCE to indicate an active connection. If DCE is not a modem (e.g. a null modem cable or other equipment), this signal should be permanently asserted (set to 0), possibly by a jumper to another signal. Data Carrier Detect (DCD) Asserted by DCE when a connection has been established with remote equipment. Ring Indicator (RI) Asserted by DCE when it detects a ring signal from the telephone line. The standard defines RTS/CTS as the signaling protocol for flow control for data transmitted from DTE to DCE. The standard has no provision for flow control in the other direction. Various implementations of compatible ports may reassign other pins for flow control. Cables

Main article: Serial Cable Since the standard definitions are not always correctly applied, it is often necessary to consult documentation, test connections with a breakout box, or use trial and error to find a cable that works when interconnecting two devices. Connecting a fully-standard-compliant DCE device and DTE device would use a cable that connects identical pin numbers in each connector (a so-called "straight cable"). "Gender changers" are available to solve gender mismatches between cables and connectors. Connecting devices with different types of connectors requires a cable that connects the corresponding pins according to the table above. Cables with 9 pins on one end and 25 on the other are common. Manufacturers of equipment with RJ-45 connectors usually provide a cable with

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

32 DE 133

either a DB-25 or DE-9 connector (or sometimes interchangeable connectors so they can work with multiple devices).

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

33 DE 133

Conventions

For functional communication through a serial port interface, conventions of bit rate, character framing, communications protocol, character encoding, data compression, and error detection, not defined in RS 232, must be agreed to by both sending and receiving equipment. For example, consider the serial ports of the original IBM PC. This implementation has an integrated circuit UART, often 16550 UART, using asynchronous start-stop character formatting with 7 or 8 data bits per frame, usually ASCII character coding, and data rates programmable between 75 bits per second and 115,000 bits per second. Data rates above 20,000 bits per second are out of the scope of the standard, although higher data rates are sometimes used by commercially manufactured equipment. In the particular case of the IBM PC, baud rates were programmable with arbitrary values, so that a PC could be connected to, for example, MIDI music controllers (31,250 bits per second) or other devices not using the rates typically used with modems. Since most devices do not have automatic baud rate detection, users must manually set the baud rate (and all other parameters) at both ends of the RS-232 connection. RTS/CTS handshaking

The standard RS-232 use of the RTS and CTS lines is asymmetrical. The DTE asserts RTS to indicate a desire to transmit to the DCE. The DCE asserts CTS in response to grant permission. This allows for half-duplex modems that disable their transmitters when not required, and must transmit a synchronization preamble to the receiver when they are re-enabled. There is no way for the DTE to indicate that it is unable to accept data from the DCE. A non-standard symmetrical alternative is widely used: CTS indicates permission from the DCE for the DTE to transmit, and RTS indicates permission from the DTE for the DCE to transmit. The "request to transmit" is implicit and continuous. Thus, with this alternative usage, one can think of RTS asserted (logic 0) meaning "ready to receive characters" from the DTE, rather than a "request to transmit" to the DCE. 3-wire and 5-wire RS-232

A minimal "3-wire" RS-232 connection consisting only of transmit data, receive data, and ground, is commonly used when the full facilities of RS-232 are not required. When only flow control is required, the RTS and CTS lines are added in a 5-wire version. Seldom used features

The EIA-232 standard specifies connections for several features that are not used in most implementations. Their use requires the 25-pin connectors and cables, and of course both the DTE and DCE must support them.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

34 DE 133

Signal rate selection

The DTE or DCE can specify use of a "high" or "low" signaling rate. The rates as well as which device will select the rate must be configured in both the DTE and DCE. The prearranged device selects the high rate by setting pin 23 to ON. Loopback testing

Many DCE devices have a loopback capability used for testing. When enabled, signals are echoed back to the sender rather than being sent on to the receiver. If supported, the DTE can signal the local DCE (the one it is connected to) to enter loopback mode by setting pin 18 to ON, or the remote DCE (the one the local DCE is connected to) to enter loopback mode by setting pin 21 to ON. The latter tests the communications link as well as both DCE's. When the DCE is in test mode it signals the DTE by setting pin 25 to ON. A commonly used version of loopback testing doesn't involve any special capability of either end. A hardware loopback is simply a wire connecting complementary pins together in the same connector. See loopback. Loopback testing is often performed with a specialized DTE called a Bit Error Rate Tester (BERT). Timing signals

Some synchronous devices provide a clock signal to synchronize data transmission, especially at higher data rates. Two timing signals are provided by the DCE on pins 15 and 17. Pin 15 is the transmitter clock, or send timing (ST); the DTE puts the next bit on the data line (pin 2) when this clock transitions from OFF to ON (so it is stable during the ON to OFF transition when the DCE registers the bit). Pin 17 is the receiver clock, or receive timing (RT); the DTE reads the next bit from the data line (pin 3) when this clock transitions from ON to OFF. Alternatively, the DTE can provide a clock signal, called transmitter timing (TT), on pin 24 for transmitted data. Again, data is changed when the clock transitions from OFF to ON and read during the ON to OFF transition. TT can be used to overcome the issue where ST must traverse a cable of unknown length and delay, clock a bit out of the DTE after another unknown delay, and return it to the DCE over the same unknown cable delay. Since the relation between the transmitted bit and TT can be fixed in the DTE design, and since both signals traverse the same cable length, using TT eliminates the issue. TT may be generated by looping ST back with an appropriate phase change to align it with the transmitted data. ST loop back to TT lets the DTE use the DCE as the frequency reference, and correct the clock to data timing. Secondary channel

Data can be sent over a secondary channel (when implemented by the DTE and DCE devices), which is equivalent to the primary channel. Pin assignments are described in following table: ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

35 DE 133

Signal

Pin 7 (same primary)

Common Ground Secondary (STD)

Transmitted

Data

Secondary (SRD)

Received

Data

as

14 16

Secondary Request To Send 19 (SRTS) Secondary (SCTS) Secondary (SDCD)

Clear

To

Carrier

Send Detect

13 12

Related standards

Other serial signaling standards may not interoperate with standard-compliant RS232 ports. For example, using the TTL levels of near +5 and 0 V puts the mark level in the undefined area of the standard. Such levels are sometimes used with NMEA 0183-compliant GPS receivers and depth finders. 20 mA current loop uses the absence of 20 mA current for high, and the presence of current in the loop for low; this signaling method is often used for long-distance and optically isolated links. Connection of a current-loop device to a compliant RS232 port requires a level translator; current-loop devices are capable of supplying voltages in excess of the withstand voltage limits of a compliant device. The original IBM PC serial port card implemented a 20 mA current-loop interface, which was never emulated by other suppliers of plug-compatible equipment. Other serial interfaces similar to RS-232: • • • • • •

•

RS-422 (a high-speed system similar to RS-232 but with differential signaling) RS-423 (a high-speed system similar to RS-422 but with unbalanced signaling) RS-449 (a functional and mechanical interface that used RS-422 and RS-423 signals - it never caught on like RS-232 and was withdrawn by the EIA) RS-485 (a descendant of RS-422 that can be used as a bus in multidrop configurations) MIL-STD-188 (a system like RS-232 but with better impedance and rise time control) EIA-530 (a high-speed system using RS-422 or RS-423 electrical properties in an EIA-232 pinout configuration, thus combining the best of both; supersedes RS-449) TIA-574 (standardizes the 9-pin D-subminiature connector pinout for use with EIA-232 electrical signalling, as originated on the IBM PC/AT)

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

36 DE 133

See also • •

Asynchronous start-stop List of device bandwidths

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

37 DE 133

References 1. ^ Electronics Industries Association, "EIA Standard RS-232-C Interface Between

Data Terminal Equipment and Data Communication Equipment Employing Serial Data Interchange", August 1969, reprinted in Telebyte Technology Data Communication Library, Greenlawn NY, 1985, no ISBN 2. ^ TIA Web site 3. ^ (1997) PC 97 Hardware Design Guide. Redmond,Washington, USA: Microsoft Press. ISBN 1-57231-381-1.

External links

Wikibooks' Serial Programming has more about this subject: Serial Programming:RS-232 Connections • • • •

RS-232 tutorial Yost Serial Device Wiring Standard Serial Port Basics RS232 serial port info

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

38 DE 133

EIA-485 From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/EIA-485"

EIA-485 (formerly RS-485 or RS485) is an OSI model physical layer electrical specification of a two-wire,[1] half-duplex, multipoint serial connection. The standard specifies a differential form of signalling. The difference between the wires’ voltages is what conveys the data. One polarity of voltage indicates a logic 1 level, the reverse polarity indicates logic 0. The difference of potential must be at least 0.2 volts for valid operation, but any applied voltages between +12 V and -7 volts will allow correct operation of the receiver. EIA-485 only specifies electrical characteristics of the driver and the receiver. It does not specify or recommend any data protocol. EIA-485 enables the configuration of inexpensive local networks and multidrop communications links. It offers high data transmission speeds (35 Mbit/s up to 10 m and 100 kbit/s at 1200 m). Since it uses a differential balanced line over twisted pair (like EIA-422), it can span relatively large distances (up to 4000 feet or just over 1200 metres). In contrast to EIA-422, which has a single driver circuit which cannot be switched off, EIA-485 drivers need to be put in transmit mode explicitly by asserting a signal to the driver. This allows EIA-485 to implement linear topologies using only two wires. The equipment located along a set of EIA-485 wires are interchangeably called nodes, stations and devices. The recommended arrangement of the wires is as a connected series of point-topoint (multidropped) nodes, a line or bus, not a star, ring, or multiply-connected network. Ideally, the two ends of the cable will have a termination resistor connected across the two wires. Without termination resistors, reflections of fast driver edges can cause multiple data edges that can cause data corruption. Termination resistors also reduce electrical noise sensitivity due to the lower impedance, and bias resistors (see below) are required. The value of each termination resistor should be equal to the cable impedance (typically, 120 ohms for twisted pairs). Star and ring topologies are not recommended because of signal reflections or excessively low or high termination impedance. Somewhere along the set of wires, powered resistors are established to bias each data line/wire when the lines are not being driven by any device. This way, the lines will be biased to known voltages and nodes will not interpret the noise from undriven lines as actual data; without biasing resistors, the data lines float in such a way that electrical noise sensitivity is greatest when all device stations are silent or unpowered. Often in a master-slave arrangement when one device dubbed "the master" initiates all communication activity, the master device itself provides the bias and not the slave devices. In this configuration, the master device is typically centrally located along the set of EIA-485 wires, so it would be two slave devices located at ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

39 DE 133

the physical end of the wires that would provide the termination. The master device would provide termination if it itself was located at a physical end of the wires, but that is often a bad design as the master would be better located at a halfway point between the slave devices. Note that it is not a good idea to apply the bias at multiple node locations, because, by doing so, the effective bias resistance is lowered, which could possibly cause a violation of the EIA-485 specification and cause communications to malfunction. By keeping the biasing with the master, slave device design is simplified and this situation is avoided. EIA-485, like EIA-422 can be made full-duplex by using four wires, however, since EIA-485 is a multi-point specification, this is not necessary in many cases. EIA-485 and EIA-422 can interoperate with certain restrictions. RS-485 can be used to communicate with remote devices at distances up to 4000 ft (1200 m) at speeds of up to 100 kbit/s at this distance. Converters between RS232 and RS485, USB and RS485, Ethernet and RS485 are available to allow your PC to communicate with remote devices. By using "Repeaters" and "MultiRepeaters" very large RS485 networks can be formed. The Application Guidelines for TIA/EIA-485-A has one diagram called "Star Configuration. Not recommended." Using an RS485 "Multi-Repeater" can allow for "Star Configurations" with "Home Runs" (or multi-drop) connections similar to Ethernet Hub/Star implementations (with greater distances). Hub/Star systems (with "Multi-Repeaters") allow for very maintainable systems, without violating any of the RS485 specifications. Repeaters can also be used to extend the distance and/or number of nodes on a network. Uses of EIA-485

SCSI-2 and SCSI-3 (for instance) use this specification to implement the physical layer. EIA-485 is often used with common UARTs to implement low-speed data communications in commercial aircraft cabins. For example, some passenger control units use it. It requires minimal wiring, and can share the wiring among several seats. It therefore reduces the system weight. EIA-485 also sees some use in programmable logic controllers and on factory floors in order to implement proprietary data communications. Since it is differential, it resists electromagnetic interference from motors and welding equipment. EIA-485 is used in large sound systems, as found at music events and theatre productions, for remotely controlling high-end sound-processing equipment from a standard computer running special software. The EIA-485 link is typically implemented over standard XLR cables more usually used for microphones, and so can be run between stage and control desk without laying special cables. EIA-485 also is used in Building automation as the simple bus wiring and long cable length is ideal for joining remote devices. EIA-485 also is used to control theatrical and disco lighting where it is used as the communications protocol for DMX signals.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

40 DE 133

EIA-485 is used to control video surveillance cameras. Typically wiring runs from a central controller to a number of cameras which have stepper motors for pan, tilt and zoom. One or more joysticks are connected to the controller and each camera is assigned an address. There appear to be a number of vendor defined protocols for communication of the actual movement requests. This standard is now administered by the TIA and is titled TIA-485-A, Electrical Characteristics of Generators and Receivers for Use in Balanced Digital Multipoint Systems (ANSI/TIA/EIA-485-A-98) (R2003), indicating that the standard was reaffirmed without technical changes in 2003. Connectors

EIA-485 does not specify any connector. Pin labelling The RS485 differential line consists of two pins: A aka '−' aka TxD-/RxD- aka inverting pin which is negative (compared to B) when the line is idle (ie data is 1). B aka '+' aka TxD+/RxD+ aka non-inverting pin which is positive (compared to A) when the line is idle (ie data is 1). These names are all in use on various equipment, but the actual standard released by EIA only uses the names A and B. However, despite the unambiguous standard there is much confusion about which is which: The RS485 signalling specification states that signal A is the inverting or '-' pin and signal B is the non-inverting or '+' pin. [1] The same naming is specified in the NMEA standards. This is in conflict with the A/B naming used by a number of differential transceivers manufacturers, including the Texas Instruments application handbook on RS422/485 communications (A=non-inverting, B=inverting). These manufacturers are incorrect, but their practice is in a widespread use. Therefore, care must be taken when using A/B naming. In addition to the A and B connections, the EIA standard also specifies a third interconnection point called C, which is the common ground. Waveform example

The graph below shows potentials of the '+' and '−' pins of an RS-485 line during transmission of an RS-485 byte:

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

ING. ALFONSO PEREZ GARCIA

41 DE 133

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

42 DE 133

References

^ Why you need 3 wires for 2 (two) wire RS485 See also

Wikibooks has a Programming:RS-485 Technical Manual

book

on

the

topic

of

Serial

RS-232 RS-422 RS-423 Modbus Profibus Fieldbus External links • • • • •

Guidelines for Proper Wiring of an RS-485 (TIA/EIA-485-A) Network Technical library of RS-485 articles and application notes RS232 to RS485 cable scheme RS422 and RS485 Standards Overview Practical information about implementing RS485

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

43 DE 133

Interface Converter RS232 to RS485 cable pinout Electrically isolated RS485 communication interface to the PC serial port

EIA-485 cable usually made with twisted pair (like EIA-422) and may span up to 1200 metres. The recommended arrangement of the wires is as a connected series of point-to-point nodes, a line or bus. Ideally, the two ends of the cable will have a termination resistor connected across the two wires and two powered resistors to bias the lines apart when the lines are not being driven. The value of each termination resistor should be equal to the cable impedance (typically, 120 ohms for twisted pairs). ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

44 DE 133

PC RS485 Interface M Asim Khan, [email protected]

This interface circuit provides electrically isolated RS485 communication inteface to the PC serial port the isolation circuit protect the PC from direct connection to hazardous voltages.

Figure 1: Circuit Diagram of Isolated RS485 Interface

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

45 DE 133

Figure 1 shows the circuit diagram of RS485 interface. Connector K1 is linked to the serial port of the PC, power to the PC side of the circuit is derived from the signal lines DTR and RTS. Positive supply is derived from RTS and negative supply from the DTR line. The RTS line is also used to control the data direction of RS485 driver IC U4. Optical isolation is achieved by optocouplers U1, U2 and U3. Opto U1 is used to control the data direction of U4 opto U2 provide RXD line isolation while opto U3 provide TXD line isolation. The other side of the isolator carries TTL levels. This side is powered by an unregulated dc supply between 9V and 18V dc. IC U5 provide 5V regulated output and IC U4 provide the RS485 bus interface. The TXD and RXD lines status are provided by data indicating LEDs. The interface has been tested at the baud rate of 19.2k baud. For Data Reception RTS = 1 (at +ve level) For Data Transmition RTS = 0 (at -ve level) DTR line is always set to 0 (at -ve level) Figure 2 & 3 shows the component layout of the isolator pcb and the track patterns respectively.

Figure 2: Component layout of the Isolator PCB ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

46 DE 133

Figure 3: Track patterns of the Isolator PCB

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

47 DE 133

Component details of the project. No 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

QUANTIT Y 4 1 1 3 2 2 1 1 1 3 2 2 3 1 2 1 2 1 1 1

DESIGNATOR C1,C2,C3,C6 C4 C5 D1,D2,D3 D4,D5 D7,D6 D8 K1 K2 R1,R2,R3 R7,R4 R5,R8 R9,R12 R6 R11,R10 R13 U3,U1 U2 U4 U5

DESCRIPTION 100nF 10uF 16V 470uF 25V 1N4148 LED RED 3mm TRANSIL 6.8V 1N4003 DB9 R/A PCB PLUG PCB TERMINAL BLOCK 4 WAY 1K8 4K7 1K 150R 680R 10R 120R H11L1 OPTO-ISOLATOR CNY17-3 OPTO-ISOLATOR MAX487, SN75176B LM7805

2 July 2001

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

48 DE 133

IEEE-488 From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/IEEE-488"

IEEE-488 is a short-range, digital communications bus specification that has been in use for over 30 years. Originally created for use with automated test equipment, the standard is still in wide use for that purpose. IEEE-488 is also commonly known as HP-IB (Hewlett-Packard Instrument Bus) and GPIB (General Purpose Interface Bus). IEEE-488 allows up to 15 devices to share a single 8-bit parallel electrical bus by daisy chaining connections. The slowest device participates in control and data transfer handshakes to determine the speed of the transaction. The maximum data rate is about one Mbyte/s in the original standard, and about 8 Mbyte/s with later extensions. The IEEE-488 bus employs 16 signal lines — eight bi-directional used for data transfer, three for handshake, and five for bus management — plus eight ground return lines. IEEE-488 / HP-IB / GPIB Type

IEEE-488 stacking connectors

General purpose data bus Production history

Designer

Hewlett-Packard

Designed

late 1960s standardized in 1975

Manufactur er

Hewlett-Packard

Produced

1960s to present Specifications

External Data signal

yes Parallel data bus with handshaking Width Bandwidth

Max devices Protocol Cable Pins Connector

8 bits 1 Mbyte/s (later extended to 8 Mbyte/s) 15 Parallel

20 meters max 24 (8 data, 5 bus management, 3 handshake, 8 ground) 24-pin Amphenol-designed micro ribbon

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

49 DE 133

Pin out

A female IEEE-488 connector Pin 1

DIO1

Data input/output bit.

Pin 2

DIO2

Data input/output bit.

Pin 3

DIO3

Data input/output bit.

Pin 4

DIO4

Data input/output bit.

Pin 5

EOI

End-or-identify.

Pin 6

DAV

Data valid.

Pin 7

NRFD

Not ready for data.

Pin 8

NDAC

Not data accepted.

Pin 9

IFC

Interface clear.

Pin 10

SRQ

Service request.

Pin 11

ATN

Attention.

Pin 12

SHIELD

Pin 13

DIO5

Data input/output bit.

Pin 14

DIO6

Data input/output bit.

Pin 15

DIO7

Data input/output bit.

Pin 16

DIO8

Data input/output bit.

Pin 17

REN

Remote enable.

Pin 18

GND

(wire twisted with DAV)

Pin 19

GND

(wire twisted with NRFD)

Pin 20

GND

(wire twisted with NDAC)

Pin 21

GND

(wire twisted with IFC)

Pin 22

GND

(wire twisted with SRQ)

Pin 23

GND

(wire twisted with ATN)

Pin 24

Logic ground

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

50 DE 133

History

In the late 1960s, Hewlett-Packard (HP), a manufacturer of test and measurement instruments[1], such as digital multimeters and logic analyzers, developed the HP Interface Bus (HP-IB) to enable easier interconnection between instruments and controllers such as computers. Early HP 9800 series[2] desktop computers used HP-IB to connect peripherals (printers, plotters, disk drives etc.). The bus was relatively easy to implement using the technology at the time, using a simple parallel electrical bus and several individual control lines; the interface functions could be implemented in simple TTL logic[3] Other manufacturers copied HP-IB, calling their implementation the General Purpose Interface Bus (GPIB). In 1975 the bus was standardized by the Institute of Electrical and Electronics Engineers as the IEEE Standard Digital Interface for Programmable Instrumentation, IEEE-488-1975 (now 488.1). IEEE-488.1 formalized the mechanical, electrical, and basic protocol parameters of GPIB, but said nothing about the format of commands or data. The IEEE-488.2 standard, Codes, Formats, Protocols, and Common Commands for IEEE-488.1 (June 1987), provided for basic syntax and format conventions, as well as device-independent commands, data structures, error protocols, and the like. IEEE-488.2 built on -488.1 without superseding it; equipment can conform to -488.1 without following -488.2. While IEEE-488.1 defined the hardware, and IEEE-488.2 defined the syntax, there was still no standard for instrument-specific commands. Commands to control the same class of instrument (e.g., multimeters) would vary between manufacturers and even models. A standard for device commands, SCPI, was introduced in the 1990s. Due to the late introduction, it has not been universally implemented. National Instruments introduced a backwards-compatible extension to IEEE-488.1, originally known as HS-488. It increased the maximum data rate to 8 Mbyte/s, although the rate decreases as more devices are connected to the bus. This was incorporated into the standard in 2003, as IEEE-488.1-2003. In addition to the IEEE, several other standards committees have adopted HP-IB. The American National Standards Institute's corresponding standard is known as ANSI Standard MC 1.1, and the International Electrotechnical Commission has its IEC Publication 625-1. Applications

At the outset, HP-IB's designers did not specifically plan for IEEE-488 to be a standard peripheral interface for general-purpose computers. By 1977 the Commodore PET/CBM range of educational/home/personal computers connected their disk drives, printers, modems, etc, by IEEE-488 bus. All of Commodore's post-PET/CBM 8-bit machines, from the VIC-20 to the C128, utilized a proprietary 'serial IEEE-488' for peripherals, with round DIN connectors instead of the heavy-

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

51 DE 133

duty HP-IB plugs or a card-edge connector plugging into the motherboard (for PET computers). Hewlett-Packard and Tektronix also used IEEE-488 as a peripheral interface to connect disk drives, tape drives, printers, plotters etc. to their workstation products and HP's HP 2100[4] and HP 3000[5] minicomputers. While the bus speed was increased to 10 MB/s for such applications, the lack of command protocol standards limited third-party offerings and interoperability, and later, faster, open standards such as SCSI eventually superseded IEEE-488 for peripheral access. Additionally, some of HP's advanced pocket calculators/computers of the 1980s, such as the HP-41 and HP-71B series, could work with various instrumentation via an optional HP-IB interface. The interface would connect to the calculator via an optional HP-IL module. Signals bus line DIO1–DIO8

description Data input/output bits. These 8 lines are used to read and write the 8 bits of a data or command byte that is being sent over the bus.

NRFD

Not ready for data. NRFD is a handshaking line asserted by listeners to indicate they are not ready to receive a new data byte.

DAV

Data valid. This is a handshaking line, used to signal that the value being sent with DIO1-DIO8 is valid. During transfers the DIO1-DIO8 lines are set, then the DAV line is asserted after a delay called the 'T1 delay'. The T1 delay lets the data lines settle to stable values before they are read.

NDAC

Not data accepted. NDAC is a handshaking line asserted by listeners to indicate they have not yet read the byte contained on the DIO lines.

ATN

Attention. ATN is asserted to indicate that the DIO lines contain a command byte (as opposed to a data byte). Also, it is asserted with EOI when conducting parallel polls.

EOI

End-or-identify. This line is asserted with the last byte of data during a write, to indicate the end of the message. It can also be asserted along with the ATN line to conduct a parallel poll.

IFC

Interface clear. The system controller can assert this line (it should be asserted for at least 100 microseconds) to reset the bus and make itself controller-in-charge.

REN

Remote enable. Asserted by the system controller, it enables devices to enter remote mode. When REN is asserted (low), a device will enter remote mode when it is addressed by the controller. When REN is false (high), all devices will immediately return to local mode.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS SRQ

52 DE 133

Service request. Devices on the bus can assert this line to request service from the controller-in-charge. The controller can then poll the devices until it finds the device requesting service, and perform whatever action is necessary.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 2 LAYERS FISICOS

53 DE 133

Connectors IEEE-488

IEEE-488 uses 24-pin Amphenol-designed micro ribbon connectors (often incorrectly termed Centronics-type), most commonly in a stackable male/female combination that allows for easy daisy-chaining by stacking cables. Mechanical considerations limit the number of stacked connectors to four or less. They are held in place by screws, which come in UTS (now largely obsolete) or metric (M3.5×0.6) threads. By convention, metric screws are colored black, as the two threads do not mate. Total cable length is limited to 20 metres, although nonstandard "bus extender" devices are available. IEC-625

The IEC-625 standard prescribes the use of 25-pin D-subminiature connectors (the same are used for parallel ports on PCs). This standard did not gain significant market acceptance against the established 24-pin connector. See also HP series 80 Rocky Mountain BASIC References ^ This portion of the company was later spun-off as Agilent Technologies ^ HP 9815 98135A HP-IB Interface ^ Examples: HP 59501 Power Supply Programmer, HP 59306A Relay Actuator ^ HP 2100 59310A HP-IB Interface ^ HP 3000 27113A CIO HP-IB Interface IEEE Standards IEEE-488.1: Standard Digital Interface for Programmable Instrumentation IEEE-488.2: Standard Codes, Formats, Protocols, and Common Commands for Use With IEEE-488.1 Press release on IEEE 488.1-2003, which allows for higher speeds External links A GPIB tutorial (mirror) from TransEra Corporation Explanation of connector stacking GPIB (2 Bits ING. ALFONSO PEREZ GARCIA

> > > > > > > > > > >

>Frame Format Start of Frame Identifier RTR Bit Control Field Data Field CRC Sequence CRC Delimiter Acknowledge Ack Delimiter End of Frame Interframe Space

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 7 DEVICENET

120 DE 133

Reference[10]

Upon transmitting the first packet of data, the "Start of Frame" bit is sent to synchronize all receivers on the network. The CAN identifier (denoted from 0-63) and RTR bit combine to set priority at which the data can be accessed or changed. Lower identifiers have priority over higher identifiers. In addition to transmitting this data to other devices, the device also monitors the data sent. This redundancy validates the data transmitted and eliminates simultaneous transmissions. If a node is transmitting at the same time as another node, the node with the lower 11 bit identifier will continue to transmit while the device with the higher 11 bit identifier will stop.[11] The following 6 bits contain information for specifying the Control Field. The initial two bits are fixed, while the last four are used to specify length field of the Data Field. The Data Field contains from zero to eight bytes of usable data.[12] The following data frame is the CRC (Cyclic Redundancy Check) Field. The frame consists of 15 bits to detect frame errors and maintains numerous format delimiters. Due to ease of implementation and immunity to most noisy networks, CAN provides a high level of error checking and fault confinement.[13] Network

DeviceNet incorporates a connection-based network. A connection must initially be established by either an UCMM (Unconnected Message Manager) or a Group 2 Unconnected Port. From there, Explicit and Implicit messages can be sent and received. Explicit messages are packets of data that general require a response from another device. Typical messages are configurations or non-time sensitive data collection. Implicit messages are packets of data that are time critical and generally communicate real-time data over the network. An Explicit Message Connection has to be used to established first before an Implicit Message Connection is made. Once the connection is made, the CAN identifier routes data to the corresponding node.[14] Conformance Test

To declare your product as DeviceNet conformant, a vendor needs to send their product to the ODVA test lab for the certification. ODVA used to have a few other test labs around the world, i.e. UK, Japan, and China. Is has now been consolidated into one that is in North America.[15] A full-test version is called the Composite test. It consists of:[16] ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 7 DEVICENET

121 DE 133

1. Conformance test. Test against the protocol specification. 2. Interoperability test. Test against devices from various vendors on a single, fully populated, network.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 7 DEVICENET

122 DE 133

Conformance Test Procedure

The following procedure shows you how to get your product certified. 1. Register as vendor with ODVA. You will be given a vendor ID. 2. Puchase a copy of the DeviceNet specification. A hard and soft copy will be sent to you. 3. Puchase the conformance test software and corresponding hardware interface card. Note that only selected interface cards from a few vendors can be used. 4. Develop and test product in-house. You would probably need help from the discussion group, see the External links below. 5. Submit your product to ODVA test lab for independent verification. 6. Repeat the above two steps until your product successfully pass the independent test. Reference[17] Sources

ODVA website DeviceNet discussion forum Introduction to DeviceNet Notes 1. ^ [1] Controller Area Network Solutions FAQ (Frequently Asked Questions). 2. ^ [2], DeviceNet Technology Overview, URL accessed 2007-02-13. 3. ^ [3] Controller Area Network Solutions FAQ (Frequently Asked Questions)], What is DeviceNet?, URL accessed 2007-02-13. 4. ^ [4] Controller Area Network Solutions FAQ (Frequently Asked Questions)], What is DeviceNet?, URL accessed 2007-02-13. 5. ^ [5] Controller Area Network Solutions FAQ (Frequently Asked Questions)], Basic DeviceNet Concepts?, URL accessed 2007-02-13. 6. ^ [6], DeviceNet Technology Overview, URL accessed 2007-02-13. 7. ^ [7], Introduction, URL accessed 2007-02-13. 8. ^ [8], Physical Layer, URL accessed 2007-02-13. 9. ^ [9], The Data Link Layer, URL accessed 2007-02-13. 10.^ [10], Table: Data Frame Format, URL accessed 2007-02-13. 11.^ [11], Introduction & Physical Layer, URL accessed 2007-02-13. 12.^ [12], Physical Layer, URL accessed 2007-02-13. 13.^ [13], Physical Layer, URL accessed 2007-02-13. 14.^ [14], The Network and Transport Layers, URL accessed 2007-02-13. 15.^ [15], Conformance Testing, URL accessed 2007-02-13. 16.^ [16], Conformance Testing, URL accessed 2007-02-13. 17.^ [17], Conformance Testing, URL accessed 2007-02-13. • • •

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 7 DEVICENET

ING. ALFONSO PEREZ GARCIA

123 DE 133

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 7 DEVICENET

124 DE 133

7.2 ESPECIFICACION. 7.3 APLICACIONES.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS

125 DE 133

UNIDAD 8 PROFIBUS 8.1 INTRODUCCION. Profibus

De Wikipedia, la enciclopedia libre Obtenido de "http://es.wikipedia.org/wiki/Profibus"

Profibus (Process Field Bus) es posiblemente el bus de campo industrial con mayor número de nodos instalados, en el año 2004 se calculaban un total de 12,6 millones de nodos. Se trata de una red abierta, estándar e independiente de cualquier fabricante, cuenta con varios perfiles y se adapta a las condiciones de las aplicaciones de automatización industrial. Fue desarrollada en el año 1987 por las empresas alemanas Bosch, Klöckner Möller y Siemens. En 1989 la adoptó la norma alemana DIN19245 y fue confirmada como norma europea en 1996 como EN50170. En el año 2002 se actualizaron incluyendo la versión para Ethernet llamada Profinet. Este tipo de red trabaja con nodos maestros y nodos esclavos. Los nodos maestros se llaman también activos y los esclavos pasivos. Además junto con las especificaciones de otros buses de campo se recoge en las normas internacionales IEC61158 e IEC61784. Características: 9.6, 19.2, 93.75, 187.5, 500, 1500, 3000, 6000 y 12000 Mbit/s. de 127 (32 sin utilizar repetidores).

Velocidades de transmisión: Número estaciones:

máximo

Distancias máximas alcanzables (cable de 0.22 mm de diámetro) hasta 93.75 KBaudios 1200 metro 187.5 KBaudios 600 metros 500 KBaudios 200 metros Estaciones pueden ser activas (maestros) o pasivas (esclavos). Conexiones de tipo bidireccionales, multicast o broadcast. Véase también • •

Modbus AS-interface

Enlaces externos • •

www.profibus.com www.procentec.com

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS

126 DE 133

Profibus From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/Profibus"

Type of Network Physical Media Network Topology Device Addressing Governing Body Website

PROFIBUS Protocol Information Device Bus, Process Control Twisted pair, fiber Bus DIP Switch or hardware/software PROFIBUS&PROFINET International (PI) www.profibus.com

PROFIBUS (Process Field Bus) is a standard for field bus communication in automation technology and was first promoted (1989) by BMBF (german department of education and research). It should not be confused with the PROFINET standard for industrial Ethernet. Origin

The history of PROFIBUS goes back to a publicly promoted plan for an association started in Germany in 1987 and for which 21 companies and institutes devised a master project plan called "field bus". The goal was to implement and spread the use of a bit-serial field bus based on the basic requirements of the field device interfaces. For this purpose, respective member companies agreed to support a common technical concept for production and process automation. First, the complex communication protocol PROFIBUS FMS (Field bus Message Specification), which was tailored for demanding communication tasks, was specified. Subsequently in 1993, the specification for the simpler and thus considerably faster protocol PROFIBUS DP (Decentralized Peripherals) was completed. It replaced FMS. Use

There are two variations of PROFIBUS, whereby DP is used most often: •

•

PROFIBUS DP (Decentralized Peripherals) is used to operate sensors and actuators via a centralized controller in production technology. The many standard diagnostic options, in particular, are focused on here. Other areas of use include the connection of "distributed intelligence", i.e. the networking of multiple controllers to one another (similar to PROFIBUS FMS). Data rates up to 12 Mbps on twisted pair cables and/or fiber optics are possible. PROFIBUS PA (Process Automation) is used to monitor measuring equipment via a process control system in process engineering. This PROFIBUS variant is ideal for explosion-hazardous areas (Ex-zone 0 and 1). Here, a weak current flows through bus lines in an intrinsically safe circuit so

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS

127 DE 133

that explosive sparks are not created, even if a malfunction occurs. The disadvantage of this variant is the slower data transmission rate of 31.25 Kbps. PROFIBUS is the only field bus that can be used in equal measure in production automation and process automation and has since become a global market leader. Worldwide, over 20 million PROFIBUS devices are in use (as of 2007). Technology

PROFIBUS Protocol (OSI reference model) 7 6 5 4 3 2 1

OSI-Layer Applicatio n Presentati on Session Transport Network Data Link Physical

DPV0

PROFIBUS DPV1 DPV2 Manageme nt

--

FDL EIA-485

Optical

MBP

Application layer

To utilize these functions, various service levels of the DP protocol were defined: • DP-V0 for cyclic exchange of data and diagnosis • DP-V1 for acyclic and cyclic data exchange and alarm handling • DP-V2 for isochronous mode and data exchange broadcast (slave-to-slave communication) Security layer

The security layer FDL (Field bus Data Link) works with a hybrid access method that combines token passing with a master-slave method. In a PROFIBUS DP network, the controllers or process control systems the masters and the sensors and actuators are the slaves. Various telegram types are used. They can be differentiated by their start delimiter (SD): No data: SD1 = 0x10 SD1

DA

SA

FC

FCS

ED

Variable length data: SD2 = 0x68 SD2

LE

LEr

SD2

ING. ALFONSO PEREZ GARCIA

DA

SA

FC

PDU

FCS

ED

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS

128 DE 133

Fixed length data: SD3 = 0xA2 SD3

DA

SA

FC

PDU

FCS

ED

Token: SD4 = 0xDC SD4

DA

SA

Brief acknowledgement: SC = 0xE5 SC SCSD: Start Delimiter LE: Length of protocol data unit, (incl. DA,SA,FC,DSAP,SSAP) LEr: Repetition of protocol data unit, (Hamming-Distanz =4 !) FC: Function Code DA: Destination Address SA: Source Address DSAP: Destination Service Access Point SSAP: Source Service Access Point PDU: Protocol Data Unit (protocol data) FCS: Frame Checking Sequence ED: End Delimiter (= 0x16 !) The FCS is calculated by simply adding up the bytes within the specified length. An overflow is ignored here. Each byte is saved with an even parity and transferred asynchronously with a start and stop bit. There may not be a pause between a stop bit and the following start bit when the bytes of a telegram are transmitted. The master signals the start of a new telegram with a SYN pause of at least 33 bits (logical "1" = bus idle). Bit-transmission layer

Three different methods are specified for the bit-transmission layer: • With electrical transmission pursuant to EIA-485, twisted pair cables with a wave impedances of 150 ohms are used in a bus topology. Bit rates from 9600 bps to 12 Mbps can be used. The cable length between two repeaters is limited to 100 to 1,200 meters, depending on the bit rate used. This transmission method is primarily used with PROFIBUS DP. • With optical transmission via fiber optics, star-, bus- and ring-topologies are used. The distance between the repeaters can be up to 15 km. The ring topology can also be executed redundantly. ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS •

129 DE 133

With MBP (Manchester Bus Powered) transmission technology, data and field bus power are fed through the same cable. The power can be reduced in such a way that use in explosion-hazardous environments is possible. The bus topology can be up to 1,900 meters long and permits branching to field devices (max. 60-meter branches). The bit rate here is a fixed 31.25 kbps. This technology was specially established for use in process automation for PROFIBUS PA.

•

For data transfer via sliding contacts for mobile devices or optical or radio data transmission in open spaces, products from various manufacturers can be obtained, however they do not conform to any standard. Standardization

PROFIBUS was defined in 1991/1993 in DIN 19245, was then included in EN 50170 in 1996 and, since 1999, established in IEC 61158/IEC 61784. Organization

The PROFIBUS Nutzerorganisation e.V. (PROFIBUS User Organization) (PNO) was created in 1989. This group is comprised of manufacturers and users from Germany. In 1992, the first regional PROFIBUS organization was founded (PROFIBUS Schweiz in Switzerland). In the following years, additional RPAs (Regional PROFIBUS & PROFINET Associations) were added. Today, PROFIBUS is represented by 25 RPAs around the world. In 1995, all the RPAs joined together into the international umbrella association PROFIBUS & PROFINET International (PI). References • •

[1] PROFIBUS system description External links • • •

PROFIBUS & PROFINET International AGILiCOM - Profibus France

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 8 PROFIBUS

130 DE 133

8.2 ESPECIFICACION. 8.3 APLICACIONES.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 9 ETHERNET

131 DE 133

UNIDAD 9 ETHERNET 9.1 INTRODUCCION. PROFINET

From Wikipedia, the free encyclopedia Retrieved from "http://en.wikipedia.org/wiki/PROFINET"

PROFINET is a standard covering the use of industrial Ethernet in automation systems and is not to be confused with the Profibus standard for fieldbus systems. There are two versions of PROFINET: • •

PROFINET CBA (Component Based Automation) for distributed systems interconnection PROFINET IO (Input Output) for controlling sensors and actuators using a central controller in production engineering

Technology

To achieve these functions, three different protocol levels are defined: TCP/IP for PROFINET CBA and the commissioning of a plant with reaction times in the range of 100ms RT (Real-Time) protocol for PROFINET CBA and PROFINET IO applications up to 10 ms cycle times IRT (Isochronous Real-Time) for PROFINET IO applications in drive systems with cycles times of less than 1ms The PROFINET protocol can be recorded and displayed using any Ethernet analysis tool. In the current version, Wireshark/Ethereal also decodes the PROFINET message frames. PROFINET CBA

A PROFINET CBA system consists of various automation components. One component covers all mechanical, electrical and IT variables. The component can be generated using the standard programming tools. A component is described using a PROFINET Component Description (PCD) file in XML. A planning tool loads these descriptions and enables the logical interconnections between the individual components to be generated for implementing a plant. This model was largely inspired by the IEC 61499 standard. PROFINET IO

A PROFINET IO system consists of the following devices: IO Controller controls the automation task. IO Device is a field device, which is monitored and controlled by an IO Controller. An IO Device comprises several modules and submodules. ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 9 ETHERNET

132 DE 133

IO Supervisor is an engineering tool typically based on a PC for parameterizing and diagnosing the individual IO Devices. An Application Relation (AR) is established between an IO Controller and an IO Device. These ARs are used to define Communication Relations (CR) with different characteristics for the transfer of parameters, cyclic exchange of data and handling of alarms. The characteristics of an IO Device are described by the device manufacturer in a General Station Description (GSD) file. The language used for this purpose is the GSDML (GSD Markup Language) - an XML based language. The GSD file provides an engineering system with a basis for planning the configuration of a PROFINET IO system. Organization

PROFINET is supported by PROFIBUS International and the INTERBUS Club and, since 2003, is part of the IEC 61158 and IEC 61784 standards. Weblinks

Industrial IT Technical Information: Information about PROFINET, Siemens AG Information about PROFINET Organization: PROFIBUS International

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI

UNIDAD 9 ETHERNET

133 DE 133

9.2 ESPECIFICACION. 9.3 APLICACIONES.

ING. ALFONSO PEREZ GARCIA

INSTITUTO TECNOLOGICO DE SAN LUIS POTOSI