I'm trying to find a discrete PID controller that is usable with openmodelica. I found the one in the linearsystems library, but there is a compile issue. Is there an easy way around this error, or do you know of another discrete PID library available?

/usr/lib/omlibrary/Modelica_LinearSystems2 2.0/DiscreteStateSpace.mo:112:3-405:20:readonly] Error: Class operators are allowed in OPERATOR RECORD only. Error on:'constructor' not found in scope 'constructor'.