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Author Topic: +X, -X axis moves in same direction. Why?  (Read 13514 times)

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+X, -X axis moves in same direction. Why?
« on: April 30, 2009, 01:52:08 PM »
I 'm hooking up a 4 Axis "StepmasterNC" motor driver box, model (SOP-2B) to a PC running Mach 3, ver 3.04.  I connected identical 4 wire stepper motors (wired identical also) to X, Y, Z & A axis. When pressing the appropriate key, +Y & -Y, +Z & -Z, +A & -A  move correctly but when pressing +X or -X, both keys move the motor in the same direction.  The same happens in MDI or if running G code. I have rearrange the interface connectors (switched motors) on the back of the motor driver box but any motor connected to the X axis only moves in one direction. Any of the four motors when connected to the Y, Z or A axis moves appropriately. My limited knowledge on electronic tells me there is something wrong with the X axis in the (SOP-2B) motor driver box. I do not think the manufacturer "StepMaster NC is still in business as my internet searches come up empty. Any help / recommendations will be appreciated.
Thanks in advance,
Brett
Re: +X, -X axis moves in same direction. Why?
« Reply #1 on: April 30, 2009, 02:02:45 PM »
Are you sure your direction pin for the X-axis is correctly configured in ports and pins, and all your connection cables for the X direction signal is correctly connected?
Re: +X, -X axis moves in same direction. Why?
« Reply #2 on: April 30, 2009, 02:39:12 PM »
The documentation says:
"X" step pin 4, dir pin 5 but the "Z" axis moves (both directions)
"Y" step pin 6, dir pin 7 with movement correct
"Z" step pin 8, dir pin 9 but "but "A" axis moves (both directions)
"A" step pin 2, dir pin 3 but "X" axis moves and in one direction
All port 1

So I switched
"X" step pin 2, dir pin 3 but "X" axis moves in one direction
"Y" step pin 6, dir pin 7 with movement correct
"Z" step pin 4, dir pin 5 with movement correct
"A" step pin 8, dir pin 9 with movement correct
All port 1

Offline RICH

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Re: +X, -X axis moves in same direction. Why?
« Reply #3 on: April 30, 2009, 03:49:21 PM »
DVSDAVIS,
Check the hotkeys assigned to each axis in CONFIG>System Hotkeys for the x axis.
In ports & pins see if the step and direction pins are the same.
If no joy, then swap the cables from one of the other axises to the X and see if 
it moves  in both directions.
I am not familar with the Stepmaster Controler.
RICH
Re: +X, -X axis moves in same direction. Why?
« Reply #4 on: April 30, 2009, 04:15:25 PM »
No Go on the hot keys as all axis and directions are different. I switched the X axis motor to the Y axis and it moved correctly. I attached the Y axis motor to X axis and it only moved in one direction. The same happens in MDI or when running a program. As mentioned before the documentation appears inncorrect. Should I try deactivating all axis but X and changed to different output pins?
Brett

Offline RICH

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Re: +X, -X axis moves in same direction. Why?
« Reply #5 on: April 30, 2009, 05:32:09 PM »
Brett,
The PC puts a pulse out to the contoller via the PP cable. So check pin 2 & 3 of the cable and see if there is continuity. If there is, then there is nothing wrong with the cable. Now if the the X pulse from the pc is making it to the contoller, then something is wrong with the wiring ( input pins 2 & 3 going to the x drive ). Do you feel confortable checking out the drive inside the controller?
RICH
Re: +X, -X axis moves in same direction. Why?
« Reply #6 on: April 30, 2009, 06:29:38 PM »
Continuity between ends for pin 2 and 3 are fine. As for the board, I open the case looking for obvious signs of damage but all looks fine. As for checking the board, sure I would try it but do not know where to begin.

Offline RICH

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Re: +X, -X axis moves in same direction. Why?
« Reply #7 on: April 30, 2009, 10:21:00 PM »
Brett,
Check that there is nothing wrong with the pc's PP. This is done with a voltage meter. Attach one lead to
pin 2 and the other lead to the cable ground. Watching the meter, jog the x axis + or - and you should see the 
voltage change. Do the same for pin #3. You may want to first see the voltage changes from  pin 6 or 7 ( your Y axis ) since those pins are working and can be used for comparison.
If not working like the Y pins then you may have a PP problem. I am guessing that you don't have a PP problem.

Turn everything off / unplug pc, contoller, etc. and take a look at the wiring inside the controller box.
Now follow the wires in the controller box from pin 2 & 3 and see if the connection to and away from the driver are ok ( ie; solid connections ). Take a look at how the wires are attached  to and from the Y drive and compare
to the x drive wiring ( maybe one is not attached properly ). Without info on your controller i can't be anymore specific.
So as a recap, you checked the pulse signal out of the pc, thru the pc cable to the controller box,  cable connection at the controller box to the drive, out of the drive to the connection for the motor.
Hope this helps,
RICH   

Re: +X, -X axis moves in same direction. Why?
« Reply #8 on: May 01, 2009, 06:50:12 PM »
I disconnected the PP cable from the motor driver box so my readings would be taken on the PP cable, end opposite the computer.
My readings were as follows:

Desc         Readings      
Axis   Type   Pin No   + Dir   "- Dir   Static
X   Step   2   0.1   0.1   0
X   Dir   3   0   3.3   3.3
Z   Step   4   0.1   0.1   0
Z   Dir   5   0   3.3   3.3
Y   Step   6   0.1   0.1   0
Y   Dir   7   0   3.3   3.3
A   Step   8   0.1   0.1   0
A   Dir   9   0   3.3   3.3

Offline Greolt

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Re: +X, -X axis moves in same direction. Why?
« Reply #9 on: May 01, 2009, 10:32:54 PM »
Brett

Those readings are pretty much what you would expect so I don't see any issue there.

People will tell you that 3.3v must be a laptop.   Not realising that most desktops put out 3.3v on the LPT also.

Most modern control hardware will cope with 3.3v no problems.  However your hardware being a bit older may not.

3.3v might be right on the edge of what the hardware will cope with and the X axis components are the only ones that are JUST missing out.

Is this a laptop?  Do you have another computer you could try?  A lot of the LPT cards (PCI) will supply 5v and don't cost much.

Having said that I don't think that explanation is likely to be your problem.

Try to logically eliminate each component as the culprit.  Pretty much as Rich has described.

Try swapping pin assignments and or connections to logically isolate where the fault lies.

Greg

EDIT:  The pin voltage check probably eliminates this but double check you don't have a pin number assigned twice in "ports and pins"
« Last Edit: May 01, 2009, 10:37:47 PM by Greolt »