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Author Topic: Problem: Losing position if more than one axis wired up to breakout board  (Read 8692 times)

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OK, I confirmed that the servos are tuned properly, but there is something really strange happening...

Move one axis by itself and everything is good. They could move for hours individually and the readouts are correct.

It seems that the errors are occurring only when X is moving in the + direction and Z is moving in the - direction at the same time.

If I jog X in the + and then move Z +, no problem.
If I jog X in the + and then move Z - , Z moves less than the DRO shows.

If I jog Z in the - and then move X - , no problem.
If I jog Z in the - and then move X +, X moves less than the DRO shows.

 ??? ??? ???

Davey Boy

Offline Hood

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I see in your xml you have the motors on different ports, is there a reason for that?
Hood
It was just easier to wire that way.

Shall I move them to a common port?

Davey Boy

Offline Hood

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Its worth a try, might also be worth using normal pins like 2, 3 , 4 etc. Could be your BOB doesnt like it.
Hood
I moved both motors to port 1... Z on 2+3 and X 5+6.  Seems to be the same issue.

Davey Boy

Offline Hood

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It does seem strange it is only in one direction. Are you using single ended step/dir signals? Have you got them shielded and grounded correctly if they are just single ended?
If the drives are not tripping then it would seem to suggest that the signals are not getting through correctly.
Hood
The signals are single ended. 

I'll run through the wires again to be sure I haven't missed something.

Thanks,
Davey Boy.

Offline Hood

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I notice you have 4MHz set in SS for X and Z axis, your steps per unit and Velocity suggest you only require 422KHz or there abouts. Set the X and Z to 512KHz in SS plugin and all the other axis you are not using set them to 32KHz.
Hood
I found it Hood.

I thought the SS was grounded, since it had what looked like a jumper on the pins. However, after I spent MANY hours going over every possible ground or wiring potential issue, I decided to have a look at that ground point. When I removed the jumper (spacer?) I found it didn't have a connection between the pins. I replaced it with a jumper I had on hand and now it seems fine. Both axis move the way they should.

Now I just need to collect up all that hair I've pulled out and stick it back into my scalp.

Thank you very much for your help with this!

Davey Boy

Offline Hood

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Good to hear its working now :)
Dont worry about the lack of hair, it doesnt hurt :)
Hood