Heartbeat
In order to monitor the connection, a heartbeat signal can be sent by the either end of the connection. If the alarm receiver doesn't receive the heartbeat in time, it may consider the connection broken and issue a warning to the operator. The alarm receiver may also send the heartbeat signal to the alarm transmitter to monitor the connection from its end. Similarly, the alarm transmitter can monitor the connection and issue an on-site warning if the alarm receiver goes off line.
<Heartbeat Id="103"></Heartbeat>