def scan_sensors(unit_value_callback = None, trigger_callback = None, **kwargs):
    for (hardware_type,sensor_device) in terrariumSensor.available_hardware.items():
      try:
        for sensor in sensor_device._scan_sensors(unit_value_callback, trigger_callback, **kwargs):
          yield sensor
      except AttributeError as ex:
        # Scanning not supported, just ignore
        pass