Jeshua Lacock wrote:
> On May 26, 2012, at 9:49 AM, Jon Elson wrote:
>   
>> Does this position change show up on the LinuxCNC DRO display, or are 
>> you reading
>> it with a mechanical indicator?
>>     
>
> Yes, it shows up on the DRO and the machine physically moves. So I guess they 
> agree.
>   
Oh, well, now, that is a bit different.  If the position display 
correctly reads the current
position, then the positioning loop is not correcting a movement of the 
system, which it
SHOULD be doing.  If the servo tuning is good, this should not be 
happening.  If a
change in position is fed back to the PID, it should send steps to the 
drive to correct
the position.

> The problem is the power wires are really close given their position on the 
> Gecko terminals. The drive in question has all 3 Gecko power lines running 
> right under it. I think this might be the problem.
>   
The encoder signals to the Gecko drive are opto-isolated from the 
encoder.  the encoder feeds
the Gecko interface board and the universal stepper board directly.  The 
Gecko interface
makes an opto-isolated copy of these signals for the Gecko drive.  While 
you may show
continuity of the grounds, the signals are actually galvanically isolated.
> Here is a pic of inside my enclosure: 
>
> <http://3DTOPO.com/CNC-enclosure.png>
>
> Don't judge me too harshly, I was making sure everything works before I 
> finish tiding things up! Any suggestions would be greatly appreciated!
>   
Umm, yeah, this has power and signal wires running all over the place.  
Some better
routing may help.  Twisting the motor wires and maybe the DC supply 
wires may
help, somebody suggested that.
> OK, so that should be the PSU DC ground then? Or the earthen ground?
>   
The power supply ground would be best, to return currents

back to where they came from.

Jon

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