Invert Stepper Direction in PNCconf

I'm using a Mesa 7i96, linuxCNC 2.9pre., and configuring with pncconf. I have a dual joint axis in which one motor's rotation needs to be in the opposite direction of the other. In pncconf, on the tb1/tb2 tab where I select stepgens, I checked "inv" on the tandem motors "Dir gen B" pin assuming that would invert it's direction. That didn't work as expected. Am I missing something here?

Finally I had to manually edit the ini file and make the step scale negative on that joint to get inverted rotation. I'm up and running, but I'd just like to know if there is a way to accomplish this in pncconf without hand editing?... Or rather I'd just like to know why the first attempt doesn't work.

Also, it seems that pncconf doesn't allow inputting negative values for stepper scale, why not?

image missing https://i.imgur.com/buD2SqS.png

Maybe it assumes a gantry would be the same direction?

Big John also has a tool but you cannot Inver the pins from it. Sometimes manual edits are needed

Leon82 wrote: Maybe it assumes a gantry would be the same direction?

I'm inexperienced with cnc, for sure. But with what I've seen in just my off handed research I would have guessed most tandem joints would run in opposite directions. Is that not the case?

No, one on each side on the gantry as it's a wide spanse usually.

I think I set my machine up so normal direction was the desired direction for that joint. On one side of the gantry I swapped the A & B phases around. But you can do it in the INI file with negative value.s

In pncconf, on the tb1/tb2 tab where I select stepgens, I checked "inv" on the tandem motors "Dir gen B" pin assuming that would invert it's direction. That didn't work as expected. Am I missing something here?

Also, it seems that pncconf doesn't allow inputting negative values for stepper scale, why not?

testing 2.8 (without hardware) i see that pncconf does add the code to invert the GPIO that should be the stepper direction output - but maybe it is the wrong GPIO - maybe Peter could confirm the numbering...

negative scales should be possible but yes I see it's not accepted - Ill see to fixing that soon.

Chris