About Sys.ServoErrorCtr

[goto.keisuke]

In my PowerPMAC software watchdog error is occurring frequently. (Once every 2 days)
After checking the variables that are likely to be related, the values of Sys.ServoErrorCtr and Sys.ServoBusyCtr are rising and I suspect they are related to errors.

I want to take measures,
would you please tell me about factors that affect the rise in Sys.ServoErrorCtr ?

[curtwilson]

In at least some servo cycles, your servo tasks are not finishing before the next servo interrupt.

Sys.ServoBusyCtr increments if the previous cycle's servo tasks are not finished when this cycle's tasks are supposed to start.

Sys.ServoErrorCtr increments if the previous cycle's tasks take so long that this cycle's tasks cannot even start.

For good performance, you should not be incrementing either of these. Even without a watchdog failure, you can get bad servo performance.

You need to look carefully both at how high your servo frequency is, and what tasks you are trying to do in the servo interrupt.

You should not be doing any tasks in the servo interrupt that are not highly predictable as to the time they need.

If you cannot change the tasks you have executing in the servo interrupt, you may need to lower your servo frequency.

You should be monitoring the servo task times, both average and peak, in the IDE's task manager.

[goto.keisuke]

(12-15-2017, 12:22 AM)goto.keisuke Wrote: In my PowerPMAC software watchdog error is occurring frequently. (Once every 2 days)
After checking the variables that are likely to be related, the values of Sys.ServoErrorCtr and Sys.ServoBusyCtr are rising and I suspect they are related to errors.

I want to take measures,
would you please tell me about factors that affect the rise in Sys.ServoErrorCtr ?

Thank you for your reply.
I proceeded with the investigation.
It seems that Sys.ServoErrorCtr is getting bigger at initialization, it seems that it is not a direct factor of WD error.

In the past few days, WD error occurred together with Sys.WDFault = 1 and 2, I am suffering from narrowing down the cause of the occurrence.

The CPU uses Dual Core, and the steady state processing load is about 30% for both FG and BG, so it seems that it is not influenced by the processing load.

The cause separation test was carried out with several devices and it was confirmed that the frequency of occurrence is the highest among the devices which communicate with EtherCAT.
(Devices with errors are used as EtherCAT Master.)

If it is a question here, assuming that Sys.WDFault = 1 and 2 are both caused by EtherCAT related processing,
What kind of setting is affecting?