Add getResponseSize() for WriteMultipleRegistersRequest

Author: Cougar

pymodbus/register_write_message.py

@@ -188,6 +188,13 @@ def execute(self, context):
         context.setValues(self.function_code, self.address, self.values)
         return WriteMultipleRegistersResponse(self.address, self.count)
 
+    def getResponseSize(self):
+        ''' Returns expected packet size of response for this request
+
+        :returns: The expected packet size
+        '''
+        return 2 + 2
+
     def __str__(self):
         ''' Returns a string representation of the instance