Prevent Blocking Managers by ignoring poll requests

[pablo.chamorro]

Hello everyone,

We are having troubles with a S7Plus driver, that some times (around once each two weeks) are generating an "ignoring poll request for Pollgroup 'pollgroup' because last request did not finish yet" errors. That, finally turns on an all managers blocked by heartbeat incluing the webclient_http control manager, and also all connections of this driver stops working by "Error resquest, The server did not response within the time specified on the client sesion". The others drivers, NGA and event manager keeps working whitout problems, so we discard network/hardware problems on the server side and we are not sure why the control managers are afected by the polling errors.

In this S7Plus driver, we have eight PLCs connections and, I think it's not a problem, but we are using a few poll groups for all the drivers (A pollGroup with a 1 second poll time, another of 2 seconds and a third of 10 seconds), always used as input direction and polling mode on the Dpes addess config.

We asume that we have any network problem with one of that eight PLCs, and it makes the poll requests takes longer, so we have to scan our network to find the problem. Anyway, we would like to know if WinCCOA have a way to know which connection is generating this trouble, and more important, if there's any strategy to avoid/prevent this behaivor. Its anoying that the whole S7Plus driver and also the control managers comes down.

I read that post in the forum and it's also interesant: viewtopic.php?p=969724#p969724

So, it's useful to have a control of how poll requests are working, like:
- Duration of each poll requests
- Poll requests per second
- The poll queue size
- List of address queried in each poll requests

We are using a 3.17 P12 version.

Thanks all.

[leoknipp]

If several managers are detected as blocking at the same time possibly there are problems with the time synchronization in your machine.
Please check the operating system logs if possibly a time synchronization was made at the the time when the manager were "blocking".

Best Regards
Leopold Knipp
Senior Support Specialist