Possible Bug With Pluto_Step?

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01 Oct 2010 23:24 - 01 Oct 2010 23:26 #4483 by Paragon
Hello All,

I was not sure of the best place to post this hence why posting here.

I think there maybe a bug either with EMC or the pluto_step firmware.

The issue arises when using pluto stepper with at least 3 axis's enabled

There appears to be some interference between the negative Y move and Z.
When a negative Y move is commanded by using the down arrow on the keyboard or via the MDI the Z axis moves up by about .4 inch and a 'Joint 2 following error' is displayed. This can be seen both on the physical machine and in the AXIS back plot.
Note: When a positive Y move is made the Y functions correctly.
X functions correctly in both plus and minus.

This issue can also be seen when monitoring with HAL Scope.

When running with only two axis enabled such as X and Y then Y functions correctly.

I am currently running EMC V2.5.0-pre.
I first noticed this issue back in 2007 but was unable to fix the issue!

Kind Regards,
SRG (Paragon)
Last edit: 01 Oct 2010 23:26 by Paragon.

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02 Oct 2010 13:36 #4493 by Paragon
Hello All,

I am pulling my hair out on this one...
I have attached a screenshot from HAL-Scope.
The screen shot showsmonitoring the following pins:-

net Ypos-fb pluto-step.stepgen.1.position-fb => axis.1.motor-pos-fb
net Zpos-fb pluto-step.stepgen.2.position-fb => axis.2.motor-pos-fb

It can be seen that when a a Y negative move is commanded interference appears on the X axis.
What part of EMC is causing this I am suspecting it's the pluto-step firmware???
Any help would be much appreciated!

Kind Regards,
SRG (Paragon)
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11 Oct 2010 18:38 #4623 by andypugh
I have had a quick look at the pluto_step driver, and it seems to look OK (line 300 here)
git.linuxcnc.org/gitweb?p=emc2.git;a=blo...ec4eed6bfeae;hb=HEAD
But then I am no expert at C or COMP.

It could plausibly be a mis-wiring in the HAL file, which files are you using?

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15 Oct 2010 12:16 #4700 by Paragon
Thanks for you reply and sorry for the delay in responding.

The config files that I am using are standard straight out of the box.
I've been going through the the C code and Comp files but am no authority on the topic.
I have also posted to the EMC mailing list but there have been a total of zero replies :(

Thanks again for your reply.
SRG

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15 Oct 2010 13:50 #4701 by andypugh
Paragon wrote:

The config files that I am using are standard straight out of the box.

Have you tried it from a liveCD boot? That would eliminate the possibility of something wrong with your specific pluto_step driver, or for that matter your specific trivkins.

I've been going through the the C code and Comp files but am no authority on the topic.

Nor am I, but I can see the problem being caused by a miss-indexing (note that the C-arrays are indexed with [] and the hal pins with (), I imagine this is because Comp does something clever with functions to emulate pin indexing. Alternatively it is the sort of error you get when someone has used " if (i = 0) " which sets i to zero, rather than comparing it to zero. [/quote]

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