Issue
There's a need to understand how COV subscriptions are established and re-established when a controller goes offline and comes back online
Environment
StruxureWare Building Operation
b3s
Cause
COV subscriptions get established with PE programming and with bindings
Resolution
The time to live for the subscription is 5 hours and gets checked every 5 minutes. If the b3 (client) goes offline eventually the subscriber server will stop the subscription after it sends out 4 messages every 3 seconds. If the acknowledge that the subscription isn’t received by the server device then it stops the subscription. The client subscriber is the one that determines the initiation of the subscription, so in this case once the b3 resets, either warm start or cool start and the program runs then the subscription would start again. A cold start would not start the subscription. If the target device goes offline, then it will be searched for with the ‘who-is’ service, and when it comes back online (the device replies with ‘I-am’), the COV subscription will be reestablished.
A binding will also attempt to setup a COV subscription. If the target device goes offline, then it will be searched for with the ‘who-is’ service, and when it comes back online (the device replies with ‘I-am’), the COV subscription will be reestablished.
