Tag values freeze

I have set up three float tags and made them historical. I then trend the values in a chart. Everything works well for anywhere between 1 - 2 hours, and then the tag values freeze. There are no errors, and the tag overlays show the tag values as good. When I log into the controller with logix5000 however, I can see that the actual tag values have changed. To fix this, I have to restart the gateway. As soon as I do, everything takes off and starts working again for another few hours. When these tags quit updating, I notice that I am unable to read/write to any other tags on the system as well, so this must be an opc-ua issue.

I’m running 7.0.5 (b4679), with CompactLogix controller (L35E)

It’s nothing as simple as the system timing out in demo mode, is it?

Unfortunatly, no. Ignition is licensed.

I’ve been watching the system closely today since I made this post, and so far, knock on wood, it has not had any hiccups. It has been running for about 4 hours now. Maybe it was something I was doing.

Other reps might have some more detailed questions for you, but I just want to say: If it happens again, call us while it is happening (don’t restart the Gateway) so that we can “catch it in the act”.

lol… I just came back in from lunch, and discovered that the tag values had ‘stalled’ again. Not 2 seconds after i restarted, I got email notification for your reply!!! Just my luck.

This time, instead of restarting the gateway, I only restarted the OPC_UA module, and the tags started updating again. If I see this happen again today, I will give you guys a call.

Do you think you could set up one of the sim drivers for me in a similar fashion (3 float tags, historical, trending in a chart) and see if those freeze also?

This will be the quickest way to differentiate between a problem with the OPC-UA Server or a problem with the CompactLogix driver.


I set up the sim dev with 3 float, historical, and am trending the values. CompactLogix tags are stalled, and the sim tags are still reading, so apparently this is a driver issue.

This problem was noticed a few days ago, and has been fixed in the latest development release 4707. Check the downloads section.

To replicate, after the subscription has been running for a few minutes, either add a new sqltag to an unsubscribed OPC items, or start a transaction group with unsubscribed OPC items. Apparently, the connections were getting dropped somewhere between the gateway and OPC driver.