S7-1200 Programmable Controller - Example_ Modbus RTU Master Program
S7-1200 Programmable controller Example: Modbus RTU master program Example: Modbus RTU master program Modbus_Comm_Load
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S7-1200 Programmable controller Example: Modbus RTU master program
Example: Modbus RTU master program Modbus_Comm_Load is initialized during start-up by using the first scan flag. Execution of Modbus_Comm_Load in this manner should only be done when the serial port configuration will not change at runtime. Network 1: Configure/initialize the RS485 module communications port only once during the first scan.
One Modbus_Master instruction is used in the program cycle OB to communicate with a single slave. Additional Modbus_Master instructions can be used in the program cycle OB to communicate with other slaves, or one Modbus_Master FB could be re-used to communicate with additional slaves. Network 2: Read 100 words of holding register data from location 400001 on slave #2 to memory location MW500-MW698.
Network 3: Move the first 3 words of the holding register data that has been read to some other location, and set a DONE history bit. This network also sets an ERROR history bit and saves the STATUS word to another location in the event of an error.
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete documentation can be found at: /dokumentation/default.aspx?DocVersionId=93176622091&Language=en-US&TopicId=81280701451 2/1/2018
S7-1200 Programmable controller Example: Modbus RTU master program
Network 4: Write 64 bits of data from MW600-MW607 to output bit locations 00017 to 00081 on slave #2.
Network 5: Set a DONE history bit when the write is complete. If an error occurs, the program sets an ERROR history bit and saves the STATUS code.
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete documentation can be found at: /dokumentation/default.aspx?DocVersionId=93176622091&Language=en-US&TopicId=81280701451 2/1/2018
S7-1200 Programmable controller Example: Modbus RTU master program
This document constitutes a free excerpt compiled by the user himself/herself from the documentation provided by Siemens for this product. Siemens disclaims all liability for the completeness of this document. It shall only be used for the user's own internal purposes. It shall not be passed on to third parties. The complete documentation can be found at: /dokumentation/default.aspx?DocVersionId=93176622091&Language=en-US&TopicId=81280701451 2/1/2018