2 steppers on one axis 5i25 - 7i76

I have 2 steppers on my Y axis. I can not get them to move at the same time. I am trying to use the pncconf wizard. I have tried doing both at Y. I have also tried one at Y and one at Y tandem. What am I missing here? Thanks.

x tandem id the right choice - unfortunately looks like there is a bug in pncconf.
Are you using linuxcnc 2.7 ?


Chris M

Well there is a small bug in the HAL file for tandem steppers but otherwise it seems to put the code in.
It wrongly sets the the control type to 0 rather then 1
I haven't tested it on a real machine though.

Maybe I'm missing something - what makes you think it doesn't work or what actually doesn't work.

Chris M

When I run the test on the Y motor, only one motor turns.

ok IIRC I believe the test doesn't set up tandem axes at all...can you test the completed config to see if it at least works.
but you have to fix the error I mentioned.
look in the HAL file (the one that starts with the config name you picked)
look for all lines similar to this:
setp hm2_5i25.0.stepgen.03.control-type 0

change the 0 to 1

I've pushed a fix for that problem - I guess I need to look at the AXIS test next.
Chris M

The axis test definitely doesn't set up tandem steppers at this time- sorry

Chris M

So create the hal and make the change?

Yes please

I don't think the joint test window in PNCconfig will move tandem motors together. (I'd be very surprised if they did anyhow.)

As I said above it doesn't -but could.
Though in master it would probably be better to put effort in using joints mode to do it.

Chris M