Hi

I am having the exact same problem.

I created a Modbus client using a S7-1200 and a Modbus server using a Siemens Logo at my office. All worked great data exchanging etc.

However, I went to my colleagues workshop and he does not have the Logo to use as a server and when I tried connecting the client to a Modbus simulator (ModTools) on my PC it will not communicate.

I know it should work because there is at least one video on YouTube that shows the exact same setup, the only difference being the IP addresses.

What was the final solution to your problem, if any?

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Split from Modbus server unable to connect to it with everything that isn't siemens.

Hello,

your problem can be exactly one important option - Device ID (MB_Unit_ID). This is simply formal RTU address what needs to be set same like on PC Server application so check device ID or similar parameter on PC as is set and you need set it to also PLC internal TAG MB_Unit_ID prior start exchange data. This is definitelly important condition that can block your data exchange not as to Server connection, this is another thing.