code: def do_WritePropertyRequest(self, apdu):
          
          if _debug: ReadWritePropertyServices._debug("do_WritePropertyRequest %r", apdu)
  
          # get the object
          obj = self.get_object_id(apdu.objectIdentifier)
          if _debug: ReadWritePropertyServices._debug("    - object: %r", obj)
          if not obj:
              raise ExecutionError(errorClass='object', errorCode='unknownObject')
  
          try:
              # check if the property exists
              if obj.ReadProperty(apdu.propertyIdentifier, apdu.propertyArrayIndex) is None:
                  raise PropertyError(apdu.propertyIdentifier)
  
              # get the datatype, special case for null
              if apdu.propertyValue.is_application_class_null():
                  datatype = Null
              else:
                  datatype = obj.get_datatype(apdu.propertyIdentifier)
              if _debug: ReadWritePropertyServices._debug("    - datatype: %r", datatype)
  
              # special case for array parts, others are managed by cast_out
              if issubclass(datatype, Array) and (apdu.propertyArrayIndex is not None):
                  if apdu.propertyArrayIndex == 0:
                      value = apdu.propertyValue.cast_out(Unsigned)
                  else:
                      value = apdu.propertyValue.cast_out(datatype.subtype)
              else:
                  value = apdu.propertyValue.cast_out(datatype)
              if _debug: ReadWritePropertyServices._debug("    - value: %r", value)
  
              # change the value
              value = obj.WriteProperty(apdu.propertyIdentifier, value, apdu.propertyArrayIndex, apdu.priority)
  
              # success
              resp = SimpleAckPDU(context=apdu)
              if _debug: ReadWritePropertyServices._debug("    - resp: %r", resp)
  
          except PropertyError:
              raise ExecutionError(errorClass='property', errorCode='unknownProperty')
  
          # return the result
          self.response(resp)
docs: Change the value of some property of one of our objects.