Ping server only if the connection is active.

devices/clients/opcua_connection.py

@@ -97,7 +97,10 @@ class OPCUAConnection(CommClient):
 		ping the client to make sure the connection with the client is still functional.
 		"""
 		try:
-			self.client.send_hello()
+			if self.connected is True:
+				self.client.send_hello()
+			else:
+				self.streams.debug_stream("Will not ping OPC-UA server {} because the connection is inactive.".format(self._servername()))
 		except Exception as e:
 			raise Exception("Lost connection to server {}.".format(self._servername())) from e