nesse

communication between two modicon m221PLC

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I have two PLC Modicon M221 PLC and a HMISTU855.
with ethernet.
I want to read/write, inputs/outputs in PLC:2 from PLC:1.
What settings are needed, and which command should be used

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Posted (edited)

Hi Nesse,

Both of PLC M221 are can communicate with each other using WRITE or READ function.

1. Firstly, you must determine which the PLC as Mater, and which is PLC as Slave. This is use to make configuration in the master PLC.

2. Make sure both of the PLC was connected in to the same network, you can check it by pinging both of PLC at the same time from your laptop.

3. Better, please convert the input and output into internal memory (%M) before mapping the register to the write or read function.

4. After got the communication, you can converted back to digital output, etc.

5. For analaog value, you can apply at the same function (writeor or read) also.

6. IMPORTANT, only 1 function (write / read) can execute at a time. If you have more than 1 function, you need additional function like up counter and flasher etc to make "scanner function" to execute the function sequentially.

Hope this can help you.

Regards,

Edited by Azdi Mus

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The ethernet cpu's have a function where you can setup dialog tables between cpu's. In the configuration click on ethernet then modtcpip. You will see the enable tickbox for this tables there

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