Upgraded to 2.7.13 -- W T F --

isolcpus=2,3




Now this looks OK to me

Obviously this story has not ended yet, still some errors!

I just rigged up work to be done and took a dinner brake and after about 2-2½ hours this on the monitor.
LNCN left power on but not F2 !!



Here the terminal output


I would appreciate if you guys can see something obvious that is way wrong in my setup here.

hm2/hm2_7i76e.0: Watchdog has bit! (set the .has-bit pin to False to resume)
hm2/hm2_7i76e.0: Smart Serial port 0: DoIt not cleared from previous servo thread. Servo thread rate probably too fast. This message will not be repeated, but the hm2_7i76e.0.sserial.0.fault-count pin will indicate if this is happening frequently.
hm2/hm2_7i76e.0: Smart Serial port 0: DoIt not cleared from previous servo thread. Servo thread rate probably too fast. This message will not be repeated, but the hm2_7i76e.0.sserial.0.fault-count pin will indicate if this is happening frequently.

hm2/hm2_7i76e.0: Smart serial card hm2_7i76e.0.7i76.0.0 local error = (13) Communication error
hm2/hm2_7i76e.0: Smart serial card hm2_7i76e.0.7i76.0.0 local error = (3) Timeout
hm2/hm2_7i76e.0: Smart Serial Comms Error: There have been more than 1 errors in 10 thread executions at least 200 times. See other error messages for details.
hm2/hm2_7i76e.0: ***Smart Serial Port 0 will be stopped***
hm2/hm2_7i76e.0: Smart serial card hm2_7i76e.0.7i76.0.0 local error = (13) Communication error

hm2/hm2_7i76e.0: Smart serial card hm2_7i76e.0.7i76.0.0 local error = (3) Timeout

hm2/hm2_7i76e.0: Smart Serial Comms Error: There have been more than 1 errors in 10 thread executions at least 200 times. See other error messages for details.

hm2/hm2_7i76e.0: ***Smart Serial Port 0 will be stopped***

That's a latency issue

I would first make sure the all power management/speed switching is disabled in the BIOS and remove the isolcpus statement in the grub config

Isolcpus typically improves dispatch latency (what the latency test and histogram display) but very often makes Ethernet latency worse

Another possibility is complete loss of communications (the watchdog bite suggest this since that means communications
have dropped out for > 50 ms) This might be a power issue on the 7I76E (if power drops out and it resets, this will happen)

Hi Peter,

If I take isolcpus out the latency values goes really bad, have a look forum.linuxcnc.org/9-installing-linuxcnc...t-f?start=150#112879
As I recall all power management is disabled

The all cores plot indicates something else is wrong, do you have WIFI enabled?

That will cause that type of latency on a BXBT1900 for example BXBT1900 with no WIFI:



BXBT1900 with WIFI:



Ethernet latency depends to some extent on gross CPU speed, you throw 1/2 of this away with isolcpus 2,3

Considering all the changes made and the error appears to be the same, I'd be looking at anything that has been the same through all this.

It is there physically (built in this NUC) but as I have no WiFi at the moment so I think it is disabled.
Even if I have WiFi (next week I will get new gear) it will be only activated when need to update etc.

PCW wrote:
This might be a power issue on the 7I76E (if power drops out and it resets, this will happen)

Could a fairly big CAP on the PSU 24VDC output smooth out, if so how many µF?

WIFI is _not_ disabled unless you specifically turn it off (it will spend its time searching for WIFI signals if not disabled)

I would


1. Remove the isolcpus statement from grub and run update-grub
2. Reboot
3. Disable WIFI
4. Try LinuxCNC again


The 7I76E takes very little 24V power so I was more thinking of a bad connection (24V with 5V of ripple would run the 7I76E fine)