I have an issue with on of my programs, the cycle time seems to be extremely long.
Based on the task configuration:
Last Cycle Time (us) = 680000 - 720000
Average Cycle Time (us) = 117920 - but constantly climbs the longer the program runs
Max Cycle Time (us) = 807659
Jitter (us) = 806802
I ran the PLC load average in the PLC Shell command and it's only showing 49%.
I set up timers and noted one PRG was taking quite a bit more time:
Task End Time PRG Start Time Difference
Time 1 5168987211 5168987174 37
Time 2 5168987212 5168987174 38
Time 3 5168987218 5168987174 44
Time 4 5168987267 5168987174 93
Time 5 5168987275 5168987174 101
Time 6 5169607023 5168987174 619849
Time 7 5168986684 5168987174 -490
I comment out that PRG in the code and the times drop drastically:
Last Cycle Time (us) = 78000 - 82000
Average Cycle Time (us) = 17000 - but constantly climbs the longer the program runs
Max Cycle Time (us) = 156104
Jitter (us) = 155213
However my PLC load actually increased to 69%.
The program is taking data points and writing them to a file on a USB, using the CAA File (184.108.40.206) library. Is there a chance it's taking so long because of writing to the USB directly? Should I look to save directly to the HMI/PLC and then transfer to the USB after saving all the required data?
If you really need to know what the root cause is without too much hassle, you should give the CODESYS professional developer Edition "Profiler" plugin a try.
It's very suited for identifying the root cause of your timing issue's!
You can always run a month demo for free ;-)
Okay, I'll have a look and see, thanks.
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