# Bad\_failure on some tags across AB PLCs **URL:** \ **Category:** Ignition\ **Created:** [May 21, 2026, 4:35pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645 "2026-05-21T16:35:01Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![aidansks](https://avatars.discourse-cdn.com/v4/letter/a/7feea3/32.png) [@aidansks](https://forum.inductiveautomation.com/u/aidansks)\ **Post date:** [May 21, 2026, 4:35pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/1 "2026-05-21T16:35:01Z")
We are having an issue where some tags across multiple PLCs having a Bad\_failure tag quality, and do not receive a value until we restart the OPC UA module on the gateway. Normally, we saw this when live edits were being done on a PLC (seemed like edits to one PLC impacted polling to all) but that would resolve itself shortly after the edit finished. Now it _seems_ to be happening when there aren't edits being done and lasting much longer requiring the module restart. There's no logs to indicate an issue, nor do we lose connection to the PLCs, there is also no communication overload (msg class 3 is fine as well), and all our driven tag groups are still polling like regular so I'm not sure where to look next. I've read into some issues on the forum about online edits on Allen Bradley PLCs and also re-browsing, but I'm not certain thats what we are experiencing. Gateway version: v8.1.27 We have multiple 5069-L340ER and L3100ERS2 PLCs on v33 firmware. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [May 21, 2026, 4:54pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/2 "2026-05-21T16:54:36Z")
> [@aidansks](#): > > on v33 firmware Eeewwww! That was plagued with bugs. You should flash update your PLCs. > [@aidansks](#): > > Gateway version: v8.1.27 That's pretty old, too. Lots of bugfixes since that was released. ---
**Author:** ![aidansks](https://avatars.discourse-cdn.com/v4/letter/a/7feea3/32.png) [@aidansks](https://forum.inductiveautomation.com/u/aidansks)\ **Post date:** [May 21, 2026, 4:59pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/3 "2026-05-21T16:59:16Z")
Thanks Phil, controls team had talk of wanting to update to v36, I'll see if we can start testing that! ---
**Author:** ![michael.flagler](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/michael.flagler/32/26272_2.png) [@michael.flagler](https://forum.inductiveautomation.com/u/michael.flagler)\ **Post date:** [May 21, 2026, 8:14pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/4 "2026-05-21T20:14:58Z")
v36 has been pretty solid from what I've seen. Just have to be careful of the change to several instructions that changed like - MOV -\> MOVE - LES, LEQ, GEQ, GRT -\> LT, LE, GE, GT - Possibly more, but those are the most frequent ones I use I'd say avoid v38 for now as it has a nasty bug that the Finalize All Edits button will sometimes just freeze Studio 5000 completely, and the only workaround last I checked was to do the old school 3 button method of Accept, Test, Assemble. ---
**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\ **Post date:** [May 22, 2026, 12:04pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/5 "2026-05-22T12:04:22Z")
> [@michael.flagler](#): > > v36 has been pretty solid from what I've seen. Just have to be careful of the change to several instructions that changed like Almost the most annoying "feature" AB has ever distributed. I just can not understand why this decision was made. Still infuriates me as I tend to type in my rung structures, and the addition/removal of charactres in those instructions battles my muscle memory. ---
**Author:** ![David\_Stone](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_stone/32/79749_2.png) [@David\_Stone](https://forum.inductiveautomation.com/u/David_Stone)\ **Post date:** [May 22, 2026, 12:12pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/6 "2026-05-22T12:12:31Z")
IEC 61131. Everyone else in the industry follows a standard of instructions, AB has finally caught up with the industry. All this shows is that you don't use any other brands. For the average integrator that has to be fluent in 10+ PLC brands, this is brining AB up to the minimum standard industry wide. ---
**Author:** ![Steve\_Laubach](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/steve_laubach/32/60900_2.png) [@Steve\_Laubach](https://forum.inductiveautomation.com/u/Steve_Laubach)\ **Post date:** [May 22, 2026, 12:14pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/7 "2026-05-22T12:14:21Z")
AB is really popular in the US. A vast majority of our PLC work is with AB. ---
**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\ **Post date:** [May 22, 2026, 12:16pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/8 "2026-05-22T12:16:32Z")
> [@David\_Stone](#): > > you don't use any other brands Actually, I do use other brands, just not as often. I have programmed Eaton, Siemens, Mitsubishi, AutomationDirect, Omron, and others. I don't struggle with those, because its not what I do everyday. I work in a factory which has 150+ PLC's everyone of which is AB. Thanks for the information, as I was unfamiliar with this being a move to IEC61131 (as that is not something I need to or care to stay up on). At least it sounds like there is a reasonable explanation. ---
**Author:** ![David\_Stone](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_stone/32/79749_2.png) [@David\_Stone](https://forum.inductiveautomation.com/u/David_Stone)\ **Post date:** [May 22, 2026, 12:18pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/9 "2026-05-22T12:18:19Z")
Pretty sure this is a move by AB so that AI PLC code actually works on AB hardware. AI isn't going to automatically check for exceptions before suggesting ladder elements. ---
**Author:** ![lrose](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/lrose/32/62724_2.png) [@lrose](https://forum.inductiveautomation.com/u/lrose)\ **Post date:** [May 22, 2026, 12:21pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/10 "2026-05-22T12:21:21Z")
> [@David\_Stone](#): > > AB so that AI PLC code actually works 😮 That is the scariest thing I have contimplated in some time. Bad enough that people are blindly trusting AI with software code, but someone taking AI generated PLC code and actually using it in the wild. Yikes! ---
**Author:** ![David\_Stone](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/david_stone/32/79749_2.png) [@David\_Stone](https://forum.inductiveautomation.com/u/David_Stone)\ **Post date:** [May 22, 2026, 12:23pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/11 "2026-05-22T12:23:15Z")
Claude: How do I make a latching coils in ladder logic without latch bits. Make the output coil hold the safety contactor on in case the batch hasn't finished. ---
**Author:** ![pturmel](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/pturmel/32/3295_2.png) [@pturmel](https://forum.inductiveautomation.com/u/pturmel)\ **Post date:** [May 22, 2026, 12:32pm UTC](https://forum.inductiveautomation.com/t/bad-failure-on-some-tags-across-ab-plcs/115645/12 "2026-05-22T12:32:20Z")
> [@David\_Stone](#): > > hold the safety contactor on 🔥 😱