Step Direction pin output.

[PaulC.]

Hello, I have a first generation shopbot that was converted, and is now being run by a pmdx-126, with a pmdx-107, and pmdx-134 controlling my g230v stepper drivers. I recently had the hardrive fail on the control computer i was using, and have started fresh with new os, and new load of mach 3. I have been able to get my e-stop, and limit switches set up, and communicating with the computer, but have not been able to get my motors to step.

When I set everything back up, I used the provided pin locations from the 134's manual (step 3,5,7 and direction 2,4,6), but so far have not been able to get the motors to step. Any help or insight you guys might have would be greatly appreciated!

[Steve Stallings]

For a system using a PMDX-134, your step and direction outputs are correct.

You may have had your system set up to require a charge pump on pin 17.
If you do not see the Outputs Enabled LED on the PMDX-126 glowing, then
this is a likely cause.

[PaulC.]

Thanks so much Steve, this was indeed the case. I can now move the motors, however everything seems to be screwy. None of the axis controls seem to be correct, with even my 2 y axis motors being driven separately by the x and y axis controls, and my x axis being controlled by the z axis controls. I should mention I did not originally wire this machine, so I hope these arent dumb questions, but is there a way to get both y-axis motors controlled by the same pins, or is this something I need to do in mach 3? also should I rewire these motor connectors to be in the right places?

again thank you very much!

[Bob at PMDX]

This is a mismatch between the step/dir pins in Mach3 and to motor connections to PMDX-134/Geckos.  It sounds like you configured the step/dir pins according to the PMDX-134 manual, with "X" on pins 2&3, "Y" on 4&5, etc.  It also sounds like the actual wiring on your machine is "Y" on pins 2&3 ("Axis #1" on the PMDX-134), "A" (Y axis slave) on pins 4&5 ("Axis #2" on the PMDX-134), and the "X" axis on pins 6&7 ("Axis #3" on the PMDX-134).  Confusing, no?

So... Go into the Mach3 Config->Ports&Pins, then click on the Motors tab and configure like this:
X - step on pin 7, dir on pin 6
Y - step on pin 3, dir on pin 2
Z - step on pin 9, dir on pin 8 (do you use the Z axis??, if not leave this line disabled)
A - step on pin 5, dir on pin 4
Click on "Apply" then "OK".

Then go to the Config->Slave Axis, and in the "Y" axis section select "A" as the slave axis.  Click on "OK", then exit Mach3 and re-start it and you should be good to go.

Bob

[PaulC.]

Thanks alot Bob, that cleared it up. I seem to be running into a problem of the slave axis, and the y axis getting out of sync when trying to home. It gets pretty violent, I have them both set with their own home/ limit switches, and the same homing speed and direction. I've been reading posts all over the web about this problem, but haven't found a definitive answer. You guys have any ideas?

Thanks so much for all the help!

[Steve Stallings]

Hi Paul,

Not sure exactly what you have happening. I am not an expert in gantry homing, but I
will try to think through it if you can describe what happens in more detail. Does it
become violent only after one of the home switches is activated? When it becomes
violent what sort of motion happens?

MachMotion did a nice video about setting up a gantry driven from both sides. The
interesting stuff is near the end of the video.

https://www.youtube.com/watch?v=uoqhKwWMWkM

Regards,
Steve Stallings
PMDX