Variate velocity according to position

[thitchen007]

Hi all,

I'm now using PCI7330 with P70530 to control the stepper motor CTP10XXX10.

My goal is to let the motor run at certain speed as a function of its current position. Is this possible to read (position) from and write (velocity) to the drive at the same time?

Thanks,

-chen

[thitchen007]

I think I need a servo motor...

[ChrisStrykesAgain]

What leads you to believe you need a servo?

[ChrisStrykesAgain]

Sorry for the double post, but I was also wondering if you have an encoder on the stepper, or are you just wanting to rely on it's positional feedback?

[thitchen007]

Christopher, many thanks for your reply. Yes, I just need to ensure the position is correct.
Do you think a real time module is necessary here? Cause 7330 seems can only output trapezoid shaped wave form for velocity, i.e. before the motor stops, I can not do anything to it. Or do you have any other suggestion? Please help, thank you again.

[thitchen007]

Sorry, I forgot to mention I will buy one with encoder...

[ChrisStrykesAgain]

I'm still looking in to this, but in the interim you might check out the joystick example (joystage.vi) located in the example finder. I believe it accomplishes something similar to what you are after.

[thitchen007]

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@OlliesCamel wrote:

I'm still looking in to this, but in the interim you might check out the joystick example (joystage.vi) located in the example finder. I believe it accomplishes something similar to what you are after.

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Christopher, thanks again for your time.

You may see the subvi called "Start Motion.flx" with a green trangle as its icon.

Once it's running, the motor will start to run, during which time I can not do anything to the motor.

Modification of it seems nontrivial to me.

[ChrisStrykesAgain]

If you are wanting to base your velocity on absolute position, it sounds as though a countour move might be ideal for what you are trying to accomplish. More on that here: http://zone.ni.com/reference/en-XX/help/371093K-01/mclvhowto/movecontourinfo/

This tool automatically creates a spline for you, blending a series of pre-determined moves in to one smooth, continuous operation. Does that sound like something that would resolve your issue?

[thitchen007]

Thanks Christopher, I was thinking about that, but contour move is not what PCI 7330 can do. I am looking for other modules now.