PLC stops execute the program, but still in run (Both in Engineer and LED on PLC)?

PLCnext Engineer
1

Hi To day i have made a change in the plc program and downloaded the complete program to the controller. Then the HMI started to make some strange faults about the OPC Tags.

I restarted the HMI many times but still the same.
Then i looked at the plc, and find all my program code is stopped. All FOR loops was “0” in debug mode.
Even ladder lines with True as contact, and some outputs as coils was off?
No reaction on force/change of variables from PLCnext Engineer…
I tryed to download the program again with no difference. Both complete and changes, with the same result. I tried power off, and on serval times and same result?
I tried reboot from PLCnext Engineer, and same result.
Then i did a reboot to factory default. then i was able to download the program (must set IP again and so on)
Now it’s working again? Has anybody tried something like this biehavure ?

After this the WBM is a little strange about the IP adress: i don’t know why, the controller has never been other adresses than 192.168.1.10 and 192.168.11.11… resetplc

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2

Now i have reproduced the problem

I made 2 variable changes and downloaded the program both Download changes, and download complete.
Now the PLC stuck in the Running mode, but not execute the program… PLCrunning1 PLCrunning2 PLCrunning3 PLCrunning4

3

Hi Emil, we’ll have a look at this asap. Regards Frank

4

Hello Emil,

This looks realy strange. can you attach a Output.log from the PLC please.
As the variables are greyed out it looks like PLCnext Engineer is unable to create a Subscription to the coils.

Can you verify that the Application is indeed not running ?

Please provide some details about the application.
Is it possible that the Watchdogs are disabled?
(that way a deadlock might occur)

I hope we can solve this soon.
kind regards,
Oliver

5

Hi Oliver I have send the file to Frank Walde.. .(i don’t have your mail address )

Task time is 10ms on both ESM, and 100ms watchdog… Please contact Frank for the log file.

6

I have same probrem with for loop. Output.log has no new entrys. I had reproduced it many times. PLC get stuck when changes are made in ‘for’ loop inside ‘for’ loop but ‘if’ as well and PLC is updated with ‘write and start project changes’. Restoring of PLC helps and same program after dowloading runs without issues. Reboot does’t help. For sure it isn’t watchdog.

7

Hello, i interest this. Some solution?

8

The problem original reported above was solved with a susequent firmware version, and should not appear when using FW 2021.0.5 and PLCnext Engineer 2021.0 or later. If you are seeing a similar problem, please give details in a separate post. ~ Martin.