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Siemens PLC Integration to an IOT Device
Integration with existing Siemens infrastructure

I have S7-300 (315-2PN/DP) PLC with 2 CP-340 Cards. 34 Energy Meters are looped and connected to these CP Cards. I also have CP 343-1 Card to connect it to SCADA PC. Now I want to acquire data of these Energy Meter on my proprietary IOT Device. But it can only take data on Modbus RTU or Modbus TCP/IP. I don't want to hamper the existing network.

Please suggest a suitable way to do it.

Thank you

Maybe you should use SIEMENS IOT2040 that can communicate with S7 PLC or Modbus TCP connection and can be use with Node-Red that can communicate with MQTT for IoT device.

I actually have my own IIOT Device which can only take data through Modbus TCP/IP or Modbus RTU.

I don't know what functionality the listed model numbers represent; whether they're even Modbus capable or if they run some other protocol.

But if the existing network is a Modbus network and the network is Modbus RTU over RS-485, then your IoT device would be 2nd master on the network, which is prohibited by Modbus serial spec because two masters on the same RS-485 network make a hash of everything. If the current master can:

- operate as a simultaneous Modbus slave
- and it has a 2nd serial port

then it can very likely make the field data available to your IoT (running as a Modbus master) which could fetch the field data from the current Master operating as a concurrent Modbus slave on the 2nd network.

If your IoT is a Modbus/TCP master then have it poll the energy meters. Yes, it adds more traffic on the network.