Hi Dan,
Yes they have displays attached but UniApps wont open when touching corner area. It does nothing at all.
One of them has VNC set up (two plcs linking together). I have tried to connect using the IP address, etc.. that's on VNC but to no avail. Cannot find the PLC at all.
They were done by an outside vendor. The are unobtainable unfortunately.
About the Modbus slave, I'm not sure if I'm honest. There are two separate plcs and they talk to each other either end of the factory.
Thanks.