encoder on step/dir system

Hello,
I have a configuration of the servo motor in position loop ( step / dir ) .
I connected servo drive encoder output to Mesa 7i77 encoder input.
I want to compare encoder.xx.position and axis.x.joint-pos-cmd.
I would like to receive a warning when the difference exceeds a certain predetermined level ( something like the following error ) .

Does anyone have something like this ?

I'm not an expert but is possible to connect step/dir signal to mesa 7i77?

anyhow following error depends on Ferror parameter, if you have ferror parameter too little you obtain following error .... LCNC control step/dir by mesa 7i77 or by other input ??

Regards
Giorgio

steva wrote: I want to compare encoder.xx.position and axis.x.joint-pos-cmd.

LinuxCNC already does this for you. All you need is for your HAL to connect the encoder feedback to axis.N.position-cmd-fb

However, it doesn't really want you, it stops all motion and turns the machine off.

If you want a pre-warning, then the HAL "wcomp" component can help. Possibly combined with the HAL "message" component.

Is that enough? Just ask, if not.

I can not find "axis.N.position-cmd-fb".

My fb signal in Axis is already used:
net x-pos-fb <= hm2_5i25.0.stepgen.00.position-fb => axis.0.motor-pos-fb

Sorry. That's the pin.
I was working from memory (I am working inTurkry, a long way from my CNC machines)