Hello,
I have deployed an application to a client using the AXC F 2152 controller. After some time of being turned on, the PLC “Run” and “Fail” flash with a 2Hz frequency. I found on the manual that this means that “system watchdog” was triggered. After this I tried to observe if there were any CPU or memory issues just before the system watchdog is triggered but it seems like those are at normal levels before it happens.
The only way around this is to reboot the whole system but after a while it happens again.
What can I do about this? Is there any logs I can find anywhere?
Any help will be much appreciated as this is an URGENT matter for me.
Thank you in advance.
Did you check the log files on the PLC?
They are located in: /opt/plcnext/logs
Maybe you’ll get more information what caused the system watchdog.
BR
DivisionByZero
I found this on the output.log file
I cannot attach a screenshot for some reason so I upload this wetransfer link with the image
https://we.tl/t-GADh70xJA3
I also found this on the watchDaemon logs folders:
System Watchdog post script called, means process died, reason: 3 add info: /opt/plcnext/data/System/Watchdog/mainProcess.pid
Wed May 28 14:49:40 EEST 2025
I found the solution to the problem.
The problem was that since the controller did not have access to the internet it could not connect to the PLCnext Store.
After 15 minutes of not being able to establish that connection it triggered a system watchdog. I found a relevant [INFO] message on the output.log file.
Solution: turned the plcnext store connection OFF completely from the system services.
This error was fixed in firmware versions 2024.0.8 LTS and 2024.6.1. From the change notes:
System watchdog Sporadically a system watchdog could occur. A possible cause of these watchdogs could be found in the connector to the PLCnext Store, especially when the PLC was not connected to the store. The system watchdog was preceded by a SIGSEGV.(contrary to this note, there’s not always an associated SIGSEGV fault)