My setup is one PLC which runs the OPC UA server, and two HMI panel PC:s with WEC7 as OPC UA clients. The projects on the HMI:s are basically identical, that is, they have the same tags which are mapped to the same PLC variables. I have about 300 tags. The idea of the system is to have two separate identical control places of the PLC. Both HMI:s can run simultaneously, but only one is the active controller at a time. When only one HMI is running, and the project on the other is stopped, everything works fine. But when both HMI:s are running there are clear problems in the variable exchange between HMI:s and PLC. For example variables are written back to their previous values spontaneously directly after trying to write a new value to it (in a situation where only one HMI tries to write the value).
My question is, what is the way to go with setting up an OPC UA connection in a system with two (or more) clients connected to one server, where the tag mappings are the same for all clients? Is there something special to consider compared to a set up with one server and one client?