# Communication lost with PLC **URL:** \ **Category:** Ignition\ **Tags:** ignition79\ **Created:** [September 18, 2025, 2:44pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755 "2025-09-18T14:44:37Z")\ **Posts on this page:** 12\ **Page:** 1
**Author:** ![yahia\_alem](https://avatars.discourse-cdn.com/v4/letter/y/8e8cbc/32.png) [@yahia\_alem](https://forum.inductiveautomation.com/u/yahia_alem)\ **Post date:** [September 18, 2025, 2:44pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/1 "2025-09-18T14:44:37Z")
I’m wondering if anyone had issu similaire to this : we have different plc connected to the scada and everything was okay someone did a modification on the plc and then we lost connection from the scada for the concerned plc. so we did a rollback on the plc and even after that we still dons’t have connection from the scada. the plc is pingable from other pc’s. and the configuration on the plc’s and the scada are exactly the same. what can be the solution ? we are sur that everything on the network and the plc is good. can we just try to remove and reinstalle the gateway ? knowing that we have two different scada and we lost connexion from both of them to the plc ![Capture d'écran 2025-09-18 161608](https://us1.discourse-cdn.com/inductiveautomation/optimized/3X/e/a/ea4acd5f3a72ebce8515406f9d1659e137b7cb5f_2_690x31.png) ---
**Author:** ![robertm](https://avatars.discourse-cdn.com/v4/letter/r/ea5d25/32.png) [@robertm](https://forum.inductiveautomation.com/u/robertm)\ **Post date:** [September 18, 2025, 3:24pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/2 "2025-09-18T15:24:34Z")
You said pingable from other PCs…is the PLC pingable from the gateway? ---
**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:** [September 18, 2025, 3:30pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/3 "2025-09-18T15:30:08Z")
Dredging back in the memory banks to 7.9, I seem to remember it being common for downloads to PLC's causing the drivers to get stuck in "connecting". I couldn't find any references to that, but its been a while. Perhaps @Kevin.Herron remembers? I would try disabling the device connection in the Gateway and then re-enabling it. If that doesn't work you could try removing the device connection and re-adding it back in. I'm not sure I would go as far as uninstalling the gateway. ---
**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:** [September 18, 2025, 3:30pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/4 "2025-09-18T15:30:50Z")
That was a Logix specific thing if we're thinking of the same issue. This just sounds like a network or PLC side issue 🤷‍♂️ ---
**Author:** ![yahia\_alem](https://avatars.discourse-cdn.com/v4/letter/y/8e8cbc/32.png) [@yahia\_alem](https://forum.inductiveautomation.com/u/yahia_alem)\ **Post date:** [September 18, 2025, 3:32pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/5 "2025-09-18T15:32:35Z")
desebling it and re-enabling it tested. also remouving it and re-adding it is tested. but it still the same for me. ---
**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:** [September 18, 2025, 3:33pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/6 "2025-09-18T15:33:00Z")
Do you see any errors in the Logs? ---
**Author:** ![amarks](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarks/32/45610_2.png) [@amarks](https://forum.inductiveautomation.com/u/amarks)\ **Post date:** [September 18, 2025, 4:03pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/7 "2025-09-18T16:03:24Z")
Did the gateway address get changed in the PLC? Try to access something on the PLC from the Ignition gateway itself. ---
**Author:** ![Cody\_Morgan](https://avatars.discourse-cdn.com/v4/letter/c/db5fbb/32.png) [@Cody\_Morgan](https://forum.inductiveautomation.com/u/Cody_Morgan)\ **Post date:** [September 18, 2025, 7:17pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/8 "2025-09-18T19:17:16Z")
I would recommend setting the Siemens related loggers to debug, then share your logs with us. ---
**Author:** ![yahia\_alem](https://avatars.discourse-cdn.com/v4/letter/y/8e8cbc/32.png) [@yahia\_alem](https://forum.inductiveautomation.com/u/yahia_alem)\ **Post date:** [September 19, 2025, 10:33am UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/9 "2025-09-19T10:33:29Z")
Hello all, I have to point the fact that the plc is accessible from everywhere except from our scada. and for information we have 2 different scada from where the plc is not reachable ( the ping dosn’t work at all ) ---
**Author:** ![robertm](https://avatars.discourse-cdn.com/v4/letter/r/ea5d25/32.png) [@robertm](https://forum.inductiveautomation.com/u/robertm)\ **Post date:** [September 19, 2025, 10:38am UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/10 "2025-09-19T10:38:03Z")
If pinging doesn’t work, it’s not an Ignition problem. It’s a networking issue. You need to verify IP addresses, switch paths, VLan settings, firewalls, etc. ---
**Author:** ![amarks](https://sea1.discourse-cdn.com/inductiveautomation/user_avatar/forum.inductiveautomation.com/amarks/32/45610_2.png) [@amarks](https://forum.inductiveautomation.com/u/amarks)\ **Post date:** [September 19, 2025, 1:17pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/11 "2025-09-19T13:17:51Z")
If you could reach the PLC before and the only thing that changed was a download to the PLC I would check the network settings in the PLC. ---
**Author:** ![Clancy\_Cavanaugh](https://avatars.discourse-cdn.com/v4/letter/c/45deac/32.png) [@Clancy\_Cavanaugh](https://forum.inductiveautomation.com/u/Clancy_Cavanaugh)\ **Post date:** [September 19, 2025, 5:26pm UTC](https://forum.inductiveautomation.com/t/communication-lost-with-plc/110755/12 "2025-09-19T17:26:59Z")
My initial thoughts would be to check the subnet mask and default gateway (Might be listed as router on Siemens PLCs) settings on the plc.