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Stepper motor moving at 0 velocity every 16,4 seconds

Hi

I hope i post this topic in the good section, if not please tell me where is the best place to post it 🙂

 

Here is the hardware we are using:

- PXI-1033 updated firmware

- PXI-7330 updated firmware

- Stepper motor 

- Driver Danaher motion No P70360 (updated firmware) adapted to the stepper

 

Here is the software we are using:

- NI Motion Assistant (updated)

- Labview 2014

 

Here is the problem:

 

We are running test but the motor position change by one every 16,4 seconds. We performed tons of velocity/acceleration/jerk tests and so on but nothing change the position drift.

We then try a 0 velocity test but every 16,4 seconds, the motor perform a new step. Idea? Suggestions?

 

The problem happens with Ni Motion AND LabView 😞

 

Ty for your help!

 

LaDyf

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Message 1 of 14
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Hi Ladyf,

 

Does the motor physically move every 16.4 seconds or does it just 'appear' to move in the software? Are the moves additive? For example, after 32.8 seconds does the stepper motor move 2 steps?

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Hi,

 

Thanks for your reply. Yes, the motor physically moves one step after a time delay, then another step after twice this delay and so on, so yes, this is additive. For the software, it does not move however.

 

Thanks.

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Message 3 of 14
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To clarify, the motor step position does NOT change in the software?

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Message 4 of 14
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well, we can see with the software that the motor step position has changed by using the "read position" vi in Labview.

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Message 5 of 14
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Hmmm. I would create a post in http://forums.ni.com/t5/Motion-Control-and-Motor-Drives/bd-p/240 since it seems like this issue is related more to the motor control side of things rather than the PXI interface. We may get more help from the community there!

 

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Message 6 of 14
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ok thanks, but just a thing, we can observe that if the motor controller is off, we still have this problem, I mean the "read position" vi indicates that after a delay, we have a motion of one step, so it seems that the command to move is sent from the software, no?

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Message 7 of 14
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How are you stopping your program? Did you create a stop button or are you clicking the Abort Execution button (you want to avoid using the Abort Execution button)? Also you want to be sure you are closing out your motion movements/references in your code before your code ends otherwise the motor could keep spinning if not properly closed and the vi aborted. I would check out some of the examples in the NI Example Finder by opening LabVIEW >> Help>> Find Examples for an idea of how some code should look.

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Message 8 of 14
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I am seeing this behavior on our PCI-7354.  If I open NI-Max software, go to interaction, set a velocity command at 0 counts / sec.  1 count will be generated approximately every 16.2 seconds.  The motion controller is driving a stepper motor in open loop, we a separate encoder connected to the motor and it is physically moving every 16.2 seconds.

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Message 9 of 14
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Has this been happening previously or is this a new development? In addition, are you observing this in software in addition to the physical movement?

Brian.D
NI Product Owner
VeriStand
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