[LAN]HeartbeatPeriod

Heartbeat parameters are used to detect bad tran connections caused by unstable network or equipment failures. The heartbeat parameters do this by exchanging heartbeat messages periodically. For example, a connection between a Plant SCADA client and server may be idle if there are no requests and no tag value updates sent.

The heartbeat packet is a probe designed to elicit a response from the other process to communicate with. If the remote process is reachable and functioning, the remote process acknowledges the heartbeat transmission by returning an acknowledgment packet. If the remote process has stopped, or is unable to respond, this situation will be detected by the local peer by monitoring packets from the remote peer in order to drop the tran channel.

It does not exchange heartbeat messages when there are other valid messages on the channel to avoid unnecessary network data.

This parameter controls how frequently a tran channel sends a heartbeat packet to the other peer.

Lowering the value for HeartbeatPeriod lets the process have less interval between heartbeat packets so that the network problem detection can speed up by configuring shorter [LAN]HeartbeatTimeout value. However, it also increases the network activity on idle connections. Conversely, increasing the value for this parameter will slow down the health checking but decrease the activity on idle connections.

Note: In order to keep network failures detected in under 5 seconds, the TCPIP socket keep alive, as a parallel mechanism, has been reinstated. This mechanism is very reliable under load as it is monitored by the TCPIP layer itself. The Keep Alive Period and Keep Alive Timeout for the TCPIP socket has been set to the value of the corresponding [LAN] parameters, divided by 5, for faster detection. This means by default the period will be 1 second and the timeout will be 3 seconds, which matches the default of the keep alive in previous versions.

Allowable Values

1 – 2147483647

Length of time in milliseconds. 0 means no heartbeat message will be sent to the other peer.

Default Value:

5000 (5 seconds)

See Also

LAN Parameters