Currently such property is not available in the API, but we will consider adding it in the next versions. What you can do is to implement your own method that will find the matching device, sensor or generic conveyor.
You can get the signals out of the devices and other PLC Resources and then check against your signal:
ITxDevice exposes the Signals property.
ITxPlcSensor exposes the Signal property.
ITxPlcGenericConveyor exposes the Signal property.