spindle speed a negative number when CCW

hahn_rossman wrote:

I'm not sure if this is a PNCconf or mesa problem, but when I issue a M04 command the spindle turns in the intended direction but the speed is wrong. When I used the hal probe to look at that pin it showed that the requested speed is negative! Is this a known problem?

It is a feature more than a problem.
The negative-value-for-reverse of the spindle speed pin is useful for driving some hardware. This includes the Mesa pwm generators which interpret the magnitude and sign as PWM duty cycle and direction (If you are interested, it happens on line 589 and onwards here: git.linuxcnc.org/gitweb?p=linuxcnc.git;a...76ef3a69e2aeb1c48929 )

What hardware are you using?

You can use the "abs" HAL function to make all values positive, and (rather usefully) the abs function has "is-positive" and "is-negative" outputs that can be used to drive direction control outputs for the hardware.
www.linuxcnc.org/docs/html/man/man9/abs.9.html

This seems likely to be a bug (my bug). I will try to fix it, but it won't be all that soon. In the meantime the abs function looks like the way to bypass it, and will continue to work after the bug is fixed.

hahn_rossman wrote:

Is it as simple as adding
loadrt abs
to the custom hal config file?

Not quite. (but nearly)

Addwhere the other loadrt lines are. Thenwhere the other addf lines are.

Then editto read
Or similar. I have guessed nearly all the signal and pin names. You should use the exact pin names that your HAL file has. You have rather more leeway with the signal names, those are created in the HAL file. The signal names are the first items after a "net" or "newsig" command.

The format of a "net" command iswith one or more pins. Only one pin linked to a signal can be an output pin. You can choose signal names. Pin names are fixed and created by LinuxCNC. The output pins you care about are motion.spindle-speed-out and abs.0.out.

If you ever create your own HAL components (and you can) then you get to choose your own pin names too. But that is for the future.