# Comunication Lost Post Firmware Update on PLC Allen Bradley L61 **URL:** \ **Category:** Ignition\ **Created:** [April 24, 2023, 4:45pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830 "2023-04-24T16:45:22Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Cesar\_Perez](https://avatars.discourse-cdn.com/v4/letter/c/b4bc9f/32.png) [@Cesar\_Perez](https://forum.inductiveautomation.com/u/Cesar_Perez)\ **Post date:** [April 24, 2023, 4:45pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/1 "2023-04-24T16:45:22Z")
Hello everyone. I had left configured the communication between Ignition 8.0 and an AB L61 PLC, I had to perform the PLC firmware update due to some inconsistencies we had, the update was made from 17.4 to 20.19. From that moment the communication with the tags that I had associated was lost and I get this message. Already restart the OPC server, but nothing. Does anyone have any idea how to solve this problem? ![ISSUE](https://us1.discourse-cdn.com/inductiveautomation/original/3X/c/6/c6755c0ce0b721373733cb3a58646e9a6c695514.png) ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 24, 2023, 4:46pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/2 "2023-04-24T16:46:42Z")
20.19 doesn't work with the legacy driver. Rockwell disabled the direct memory access method it uses to read tag values. I think 20.18 is the last version that works. You'll have to downgrade the firmware or switch to the new Logix Driver, fixing any OPC Item Paths that no longer work, and accepting the severe performance penalty that comes along with using that driver with a firmware version less than 21. ---
**Author:** ![Felipe\_CRM](https://avatars.discourse-cdn.com/v4/letter/f/dfb087/32.png) [@Felipe\_CRM](https://forum.inductiveautomation.com/u/Felipe_CRM)\ **Post date:** [April 24, 2023, 4:54pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/3 "2023-04-24T16:54:44Z")
> [@Kevin.Herron](#): > > severe performance penalty Out of curiosity, is @pturmel's driver any more performant for the v20.19-v21 range, or is it purely a limitation of the firmware version? ---
**Author:** ![Cesar\_Perez](https://avatars.discourse-cdn.com/v4/letter/c/b4bc9f/32.png) [@Cesar\_Perez](https://forum.inductiveautomation.com/u/Cesar_Perez)\ **Post date:** [April 24, 2023, 4:56pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/4 "2023-04-24T16:56:15Z")
Hi Kevin, thanks for your reply. In the firmware update I had to update 3 PLCs with the same characteristics, of which only 1 gave me this failure. Why do you think this is? ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 24, 2023, 4:56pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/5 "2023-04-24T16:56:21Z")
I don't think so, I think it uses the same "API" we do. Any performance gains would be from his work reverse engineering AOIs or other differences in request packing / optimization. ---
**Author:** ![Kevin.Herron](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/kevin.herron/32/7259_2.png) [@Kevin.Herron](https://forum.inductiveautomation.com/u/Kevin.Herron)\ **Post date:** [April 24, 2023, 4:57pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/6 "2023-04-24T16:57:04Z")
> [@Cesar\_Perez](#): > > of which only 1 gave me this failure. Why do you think this is? The others aren't 20.19, aren't using the legacy driver, or you haven't looked close enough to notice the reads failing yet. ---
**Author:** ![Cesar\_Perez](https://avatars.discourse-cdn.com/v4/letter/c/b4bc9f/32.png) [@Cesar\_Perez](https://forum.inductiveautomation.com/u/Cesar_Perez)\ **Post date:** [April 24, 2023, 5:09pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/7 "2023-04-24T17:09:07Z")
I think I will have to downgrade the firmware to 20.18. However, it's the same application, same plc model, and same firmware version, and two run and the other doesn't. ![ISSUE1](https://us1.discourse-cdn.com/inductiveautomation/original/3X/1/d/1db6630f14f2f5368787d41f7f562ff8743d3b25.png) ---
**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:** [April 24, 2023, 5:22pm UTC](https://forum.inductiveautomation.com/t/comunication-lost-post-firmware-update-on-plc-allen-bradley-l61/72830/8 "2023-04-24T17:22:53Z")
> [@Kevin.Herron](#): > > I think it uses the same "API" we do. Correct. I use the V21+ API for all versions, and simply fall back to exclude the instance number optimization if the processor indicates they aren't available. I intend to eventually apply the pre-v21 physical memory services (the insecure ones) where supported, but that is **way** down my priority list.