[LAN]HeartbeatTimeout

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 a server could be idle for a while 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.

To avoid unnecessary network data, heartbeat messages will not be exchanged when there are other valid messages on the channel.

This parameter controls how long the network may be idle prior to dropping the tran connection. In lowering the value for HeartbeatTimeout the process may speed up network problem detection. However, it could also lead to drops in connection due to momentary problems. Conversely, increasing the value for this parameter will slow down the health checking but the process will be able to ignore momentary issues.

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 drop will happen.

Default Value:

15000 (15 seconds)

See Also

LAN Parameters