Hello Experts,

We are currently in the design phase of a system with 24 PLC's.
CPU is BMXP342020 [ CPU onboard Serial and Ethernet ports, both capable of MODBUS]

Each PLC's are stand-alone and have communication with 9 Modbus RTU slaves.
Also, each PLC will be connected to OPC at central SCADA room via MODBUS TCP.

Regarding Serial MODBUS RTU
1. CPU onboard RJ45 Serial port can directly make communication with all 9 slaves via multidrop? Using READ VAR/WRITE VAR function?
2. How many READ VAR/WRITE function can be used simultaneously?

Regarding MODBUS TCP
1. Which module is required for connecting to OPC?
BMX NOC 0401 or BMX NOE 0100?
Can the above two modules be connected to OPC without any programming? We need to read/write data to each CPU all the time.

2. Does BMX NOC 0401/BMX NOE 0100 need programming in PLC for communication?

3. Does CPU onboard ethernet port require programming for communicating on MODBUS TCP?

Please guide.

We have used M580 CPU in 10 projects and all the time DCS [Client] can read/write data with M580[server] without any programming. But we used CPU onboard port or BME NOC 0301.2

So does that sounds similar to BMX NOC 0401/BMX NOE 0100