Saravana kumar

Dear All,

Hereby I have attached updated version of the sample project for themodbus communication between CP341 (Modbus Master Module) and the third party slave deviceswith the one sample slave device manual for what the project is made.

In this program I have usedFB50 as the Modbus standard block; this block can be called multiple times in your program. One block call is for one number of CP341 Modbus master modules.

This program is the tested one and I am using it in my projects,

Blocks associated with the FB50 is,

FB 7 = Modbus_Rcv (Siemens standard block)

FB 8 = Modbus_Send (Siemens Standard Block)

DB1 = Send list DB (Modbus Queries list)

DB4 = Modbus Data (Received Data’s)

Advantages of using this block / Information about Update ,

1. You can set more then one query to the modbus slave devices upto 128 queries.
2. Communication failure status for each query (available as the FB 50 Var.Out).By using this, it is easy to get the healthiness of the slave devices located in various location of the plant.
3. No need to use pulse time for query increment. Jump from one query to next query is depending on the reply for the previous query.
4. Receive list offset can be entered directly in the Send List DB as the last byte of each query, no need of additional logic.
5. You can call the FB 50 multiple times inside the program with the associated blocks for the one more Modbus Master module (CP341).
6. Use Modbus variable table in the sample project for testing of your devices.
7. Misc DB is removed and the blocks inputs are direcly connected to the FB 50.
8. Block basic structure is maintained and the modified the logics with more comments for better understanding of the logic.

Use the Modbus block and achieve communication tasks quickly and easily without any problem.

Please revert back for any clarification.

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Best Regards
T.Saravana Kumar

"All for the Best"

Attachment:Modbus V2.0.zip (14 Downloads)

Hi!

I need to use Master CP 341 for data exchange with two CPU 224 (read and write). Can you explain how I can write data (several registers) to cpu 224 with your function? It will be fine if you can provide example.

Best regards