Welcome. I want to communicate between a WINCC RT and a PLC 1200 via OPC UA, using 2 SIM cards to communicate between them. When I associate a tag with the address from the PLC, WINCC sees the PLC , but when I run RT it doesn't work, only ##### appears, I mention the fact that communication works on WINCC 8.0, so no other changes should be made in the PLC.

And if I put an internet cable between PLC and WINCC RT it works.

Can you help me?

Hello RoxanaMorar

So I think S71200 is OPC UA Server (because it can not act as OPC UA Client) and the WInCC Runtime Advanced is OPC UA Client?

Do you have checked this FAQ: https://support.industry.siemens.com/cs/ww/en/view/63481236

There are examples for each side.

Check also in the rejected folders of the RT Advanced Client certificate folders if there is a rejected PLC certificate (dometimes you have to trust also if you do not use security)

Bye Murof