servo power on/off as an iocontrol output?

17 May 2018 21:35 #110821 by lakeweb
Hi All,
I'm running with a Mesa 7i92/7i77 and I'd like any fault that sets the servo power button to off also kill my servo power. I have servo power wired to the e-stop, that works. But my catch is when linuxcnc goes into servo power off, the idle voltage from the 7i77 changes and the servos start to drift. For now I just reach over and hit F1 to kill the servos but what if I forget or didn't see it? Is there any way to get a signal from the 'servo power toggle(F2)'. I have searched but can not find it.

Thanks, Dan.
17 May 2018 22:49 - 17 May 2018 22:52 #110823 by PCW
You should never see drift, this means the drives are enabled when PID is not running which is a safety issue

Normally you would control the physical enable on the drive with LinuxCNCs amp-enable-out signal

( Theres one hal amp-enable-out pin per joint/axis but you can use the axis/joint 0 signal for all drives)
Last edit: 17 May 2018 22:52 by PCW.
The following user(s) said Thank You: lakeweb
17 May 2018 23:35 #110826 by lakeweb
Thanks! And I guess that as I can't share the signal on a second line, writing:

'net emcmot.00.enable hm2_7i92.0.7i77.0.0.output-06 <= axis.0.amp-enable-out '

is fine. The servo relay is on pin 6 of the 7i77.

And yes I know drift is bad. This came up yesterday as I started re-configuring my hardware. I had the zeros set for when the board was inactive. But it was annoying to have the servos bouncing when linuxcnc was active and the zeros would shift.

Now the servos are enabled only when 'servo power toggle' is set on.

It was time, I'm working the machine for jobs now. Cut my first piece of 304 last weekend! Had done a couple of 303 jobs before. This stuff is fun!

Best, Dan.
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