public ExternalSignalTallyBoolean(ExternalSignal signal, ExternalSignalTally tally, SignalTallyColor color) :
     base(tally, color)
 {
     this.signal = signal;
     updateFields();
     signal.IdChanged    += signalIdChangedHandler;
     signal.NameChanged  += signalNameChangedHandler;
     tally.StateChanged  += signalTallyChangedHandler;
     signal.ModelRemoved += signalRemovedHandler;
     if (signal.ID > 0)
     {
         register();
     }
 }
 public ExternalSignalTally(ExternalSignal parentSignalSource)
 {
     ParentSignalSource = parentSignalSource;
 }