I have started a OPC UA Server in the OMShell with  simulate(test, startTime = 0.0, stopTime = 120.0, simflags = "-rt 1.0 -embeddedServer opc-ua"). Then I wanted to test it with the OPC UA client UA Expert. Unfortunatly I cannot write any variables other than boolean like the variable run to start the simulation.
When I try to change a value I get an error that the value could not be converted to variant type OpcUaType_Double. When I tried using a different client it said that non of the variables were readable nor writable.

My model is:

model test
  input Real x;
  Real y;
equation
  y = x;
end test;

EDIT: Aparrently the OPC UA functionality is not yet fully implemented. I found several bugs from this month on their github that describe my problem. That is why I won't be able to use Openmodelica for my project.