SSI absolute encoders and analog servos

Looking at this chart, should timer be set at 450 us?

Tero

No, that's the timeout value the timer should be set to read ahead the transmission time (80 usec for 32 bits at 400 KHz)
plus a small margin, so -100 usec should be fine

Can you post all your current SSI related settings here

Also take a look at DPLL phase-error-usec in case there's a locking problem (though I would not expect this)
(it should not ever be greater than you jitter numbers)

Related config:

loadrt hm2_pci config="ssi_chan_0=xencoder%32e

#SSI stuff
setp hm2_5i25.0.ssi.00.frequency-khz 400
setp hm2_5i25.0.ssi.00.timer-number 1
setp hm2_5i25.0.dpll.01.timer-us -150
setp hm2_5i25.0.ssi.00.xencoder.scale 10000

Tero

Also what LinuxCNC version

Recently updated to 2.7.6

Hi,

Also found this from terminal:

Message from syslogd@Cinci at Aug 25 08:54:14 ...
kernel:[ 545.868700] NMI: PCI system error (SERR) for reason a1 on CPU 0.

Message from syslogd@Cinci at Aug 25 08:54:14 ...
kernel:[ 545.868707] Dazed and confused, but trying to continue


Related?

Might be related, sounds like a PC hardware error of some kind

I believe it is a bug within graphics adapter firmware. Those errors were present before this timing warning

Tero

How can I debug this issue more to find out actual cause for timing warning.

I would try to eliminate the NMI, this is not going to be good for real time performance
Also, as I mentioned, you could monitor (via halscope for example) the dpll error so see if it loses sync do to
some real time issue with your system