Hello Everyone,

       Basically, I have two questions. I am working on CPU316-DP which is communicating with non-siemens HMI (ESA) over MPI protocol.

       In this CPU, there only one MPI port is present.

Can I add one more HMI (Siemens only) parallel to existing HMI using profibus cable and Profibus connector? 

    I think it should work, but just want to clear doubt.

[snip]

 Awaiting for your response asap.

Thanks.

Regards,

Shailesh

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Split from How to communicate S7-1200 CPU with S7-300 CPU over profibus?.

Hello,

yes, you can add another node to your MPI network, pay attention to correct addressing, speed settings and also max. distance between nodes. Use Profibus cable and connectors. [snip]

Duris_I

Hello,

yes, you can add another node to your MPI network, pay attention to correct addressing, speed settings and also max. distance between nodes. Use Profibus cable and connectors. Profibus DP connection between both systems (S7-1200 and S7-300) depends what type of S7-300 CPU you have and which device will be Master and which Slave. To this selection you also need module to S7-1200. You can define I/O buffer to Profibus communication via available defined slots in HW cfg (1 byte, more bytes to Send/Receive).

 Thanks for lightning fast reply. 

Yes, for sure, will check MPI address and Baud rate (187.5 kbps). As MPI is RS-485 protocol, it can communicate over 1500 meter, I think.

[snip]

Hello s_vb;

You must be very careful when planning the MPI bus, especially when considering distances.

MPI ports come in 2 models: a non-isolated one (ports that are only used for MPI) and isolated (ports that can be configured for MPI or Profibus).

If your CPU has an MPI port that can only be used for MPI, then the port is non-isolated, and the maxiimum diatance ypu can conect your MPI nodes on a segment is 50m.

Exception: you can use 2 RS-485 repeaters to extend the distance to 1000m, as long as there are no MPI nodes between them. See the attachment below for an illustration.

If on the other hand you have a port designated MPI/DP, then it is isolated. The longest distance for a segment is then 1000m, at 187,5 kB.

See the following discussion for more information:

https://support.industry.siemens.com/tf/ww/en/posts/maximum-length-for-mpi-50m-but/25016/?page=0&pageSize=10

Hello,

also addition to Daniel's helpful infos:

https://support.industry.siemens.com/tf/us/en/posts/mpi-communication-distances/73905?page=1&pageSize=10