Hi,

I'm new to PLC and MODBUS, need helps and advises from gurus here.

Currently I have multiple EGXs connected to a ethernet switch. So, now I required to pull data from these EGXs and display on the SCADA.

The PLC model I'm using is Modicon M340 with BMX P342020 CPU. It has 2 ports, ethernet and modbus TCPIP, and the ethernet port is already used to link to the SCADA.

Now, if I wanted to pull data from the EGX, can I read the data by connecting an ethernet cable from the modbus TCPIP port (on the PLC) to ethernet switch? Or I required to add an additional BMX NOE0100 ethernet card to pull data with IO scan?

 

Modicon M340 (2020) has 1 ethernet port and 1 serial 485 port

Ethernet port communicates with Modbus TCP protocol
RS485 port communicates with Modbus RTU protocol

You could use integrated ethernet port even if already connected (of course to the same network), but you can't use I/O scanning service. Or you could add the NOE module and use I/O scanning service (if you prefere).

Some (it depends on the requested performances, cable length, etc.) slave devices could be directly connected to the serial RS485 integrated port without EGX nor switch (it's not ethernet although RJ45 connector)

 

Why not have the SCADA read the EGX on RS485 if Modbus TCP is not available? Does the plc have to act on the data? If you are just logging it in the SCADA bypass the plc.