OPC Server AE Status: "Max Number of AE subscriptions exceeded"
Does this status mean that...
the max limits set in AE settings have been exceeded (queue size or Max no. alarms)
Too many OPC Servers are trying to subscribe to this certain PM864 OPC AE.
What would be solution to this status?
Version is 188.8.131.52.
Voted best answer
This can be due to a too low "AE Max No Of Subscriptions" setting which defaults to 1. When using a redundant OPC server configuration, this setting needs to be increased to (at least) 2.
Another possibility is that other connections fight for resources, e.g. PP800 can also connect via MMS AE and likewise need a free queue slot to use.
In the past, the controller could sometimes fail to purge old stale MMS AE connections (it is done by some cyclic interval, so be patient if there has been a recent restart of a MMS AE client).
To view current MMS AE connections, use Control Builder M to go online with the controller, call the Interaction Window for Program3.SystemDiagnostics function block which is by default running in the Slow task of new controllers (you may move it elsewhere if you like). If you have removed this very useful function block I recommend that you download it again to some slow running task. Enable cyclic update, then go to Advanced > Alarm & Event > Subscribers to view which are present.
If you see old & stale subscriptions occupying critical queue space, take some screen captures and file a support case with your regional ABB support center.
FYI: there has been problems with connections made via secondary network path (see past Product Alerts published on ABB Library). Please read the following alert 3BSE047421D0130