We have our HMI (IntelliMAX) that will poll data from 300 PLCs. The communication will be done thru a radio MDS Transnet. From the HMI to the Master radio is PROFIBUS DP, and the same in the slave radio to the PLC. We will get an OPC server for PROFIBUS to be able to talk to the PLCs.

Question is:
1. Does PROFIBUS take care of the polling when is radio based? The OPC server cannot request all the data, otherwise will take all bandwidth.

2. Normally the radios are protocol transparent? Meaning that I can send data to other devices using PROFIBUS or Modbus. Obviously one radio only will send data for one protocol, in this case it will be PROFIBUS.

 

The Profibus ports on the S7 300 PLCs and the OPC on the PC work fine on any media.

In case of radio networks the baud rate should be matched with the profibus network settings in the HW configuration of the PLCs and PC. Thus the radio network is invisible to the PLCs or the OPC communicating on Profibus protocol. Since the protocol being used by OPC is Profibus, data overflow is not a problem if baud rate is matched.