The Property ReferenceValue represents the monitored value.
The Property SetpointValue represents the setpoint value.
The Property ErrorLimit represents the error limit. It is the LowDiffLimit if
a) the new state is LOW_LIMIT, or
b) CurrentState is LOW_LIMIT and the new state is NORMAL
It is the HighDiffLimit if
a) the new state is HIGH_LIMIT, or
b) CurrentState is HIGH_LIMIT and the new state is NORMAL