PLC to PLC Communication

NETWORKING SOLUTIONS
1

Hello,

I have two Schneider M221 PLCs. Each is connected to a TRB140, each has routes configured in the RMS VPN.

I from each TRB140 I can ping the local PLC as well as the remote one via the VPN. With the Open VPN client on my PC I can also ping each PLC.

I have followed the instructions here on Firewall settings:
https://wiki.teltonika-networks.com/view/RMS_VPN_Hubs

When I use an Ethernet cable between the two PLCs connected directly, they communicate OK and can read data on each other. However when connected as above, they are not able to communicate.

Any ideas?

2

If I’m not wrong here, there’s no Gateway configuration possible for some PLC’s hence the traffic to them needs to be masqueraded.
This makes sure that the packet’s which come in also know their way back to where they came from.
Not 100% sure though.

3

Many thanks for the reply.

I can set the gateway in each PLC - they are set to the LAN IP of the TRB140 gateway (192.168.2.1).

Would the above explain why I can collect data from them both with a Modbus scanner (TCP) running on my PC (with then OpenVPN client installed)? I just can’t get them to collect data from each other.

4

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