OPC UA subscriptions not visible any more

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tpjctrl
Posts: 66
Joined: Tue May 08, 2018 10:30 am

OPC UA subscriptions not visible any more

Post by tpjctrl »

Stumbled upon a strange issue today. I've had a bunch of subscriptions configured for OPC UA Clients and 100+ address configs using those subscriptions. For whatever reason now all those subscriptions are not visible in any of the OPC UA Client subscription dialog popups (it's as if they don't exist), but looking at the database, under _OPCUASubscription datapoint type, I can still see all of them. Also, if I do an export of all address configs for all datapoints, I can also see that they are all using the previously configured subscriptions. I've noticed that when I try to view the subscriptions for a given OPC UA Client (System Management->Driver OPC->OPC UA Client->Manage Subscription), the following error is shown in the Log Viewer:

WCCOAui (2), 2021.03.26 10:17:07.679, IMPL, WARNING, 54, Unexpected state, DpIdentifier, formatValue, could not convert DpIdentifier to string: (Type: 0 Sys: 1 Dp: 1021656 El: 0 : ..)

So it seems like it can't show the subscription name in the Manage Subscription popup for this reason, any idea why this happens?

FYI this was all working fine roughly a week or so ago.

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leoknipp
Posts: 2477
Joined: Tue Aug 24, 2010 7:28 pm

Re: OPC UA subscriptions not visible any more

Post by leoknipp »

If this error is written a DP ID cannot be resolved into a string.
Is there an additional log message written in which code the error occured or do you get just 1 log message?

Can you please check if the list of subscriptions in the DP element <_OPC_UA server datapoint>.Config.Subscriptions matches the subscriptions defined in your system.

Best Regards
Leopold Knipp
Senior Support Specialist

tpjctrl
Posts: 66
Joined: Tue May 08, 2018 10:30 am

Re: OPC UA subscriptions not visible any more

Post by tpjctrl »

No I only get a single log message.

Here's an example for a datapoint which has an address config set up, ascii export of the address config shows this:

UI (2)/0 [dpname] SITE 16 "WH3-GW$WH3-GW-SUBSCRIPTION$1$1$ns=2;s=[address]"

Yet when you view the address config in PARA, there's no subscriptions shown. Here's the warning shown in the log when I try to view the list of subscriptions by clicking the "..." button next to Subscription drop down list on the address configuration popup:

WCCOAui (2), 2021.03.30 11:53:46.645, IMPL, WARNING, 54, Unexpected state, DpIdentifier, formatValue, could not convert DpIdentifier to string: (Type: 0 Sys: 1 Dp: 1021583 El: 0 : ..)

Ascii export for this particular _OPCUASubscription datapoint, shows this:

_WH3-GW-SUBSCRIPTION _OPCUASubscription 1021583

You can see the DpID matches the warning. And finally, here's the Config.Subscriptions datapoint element from the _OPCUAServer datapoint:

_WH3-GW.Config.Subscriptions is (Type: 0 Sys: 1 Dp: 1021583 El: 0 : ..)

Again, same DpID.

As you can see all the names match as well.

I've added all subscriptions manually, from the System Manager and at one point they were all visible and working fine, but for whatever reason it broke and now all address configs revert back to using Polling (and no Poll Group configured as this was never the intended Receive mode to use!).

Two questions:

- how to fix this (I reckon delete all subscription datapoints and re add them?)
- why does this happen and how to make sure it doesn't happen again on a production machine?

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leoknipp
Posts: 2477
Joined: Tue Aug 24, 2010 7:28 pm

Re: OPC UA subscriptions not visible any more

Post by leoknipp »

It looks like the DP-ID and the name should match.
Can you restart the WinCC OA project?
Does the problem still occur after a restart?

If you need further assistance you can get in contact with your common WinCC OA support.

Best Regards
Leopold Knipp
Senior Support Specialist

tpjctrl
Posts: 66
Joined: Tue May 08, 2018 10:30 am

Re: OPC UA subscriptions not visible any more

Post by tpjctrl »

Indeed DP-IDs / names match and all was working fine some time ago, but suddenly it started reporting the DpIdentifier conversion error (no changes were made in the project recently so this is rather unexpected).

Restarts don't change a thing unfortunately.

I'll log this as a bug.

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