How best to perform microstepping with a 6024E DAQCard and SC-2345 connector block?

[embr13]

We have a need to control an ARUN C14.1 stepper motor within the confines of existing equipment. We have an SC-2345 connector block interfacing with a 6024E PCMCIA DAQCard, and were hoping for suggestions concerning the SCC modules to employ. So far, we are thinking about stepping through a phase-polarization sequence (defined in Labview) using four SCC-D0O1 modules, each attached to a four-channel push-pull driver (L6220) to supply the necessary current. The questions we have are:

In terms of full- or half-stepping, does the proposed setup seem reasonable?

What additions/modifications would be needed to achieve microstepping?

[risheeb]

Hi embr13,

Thank you for posting on the National Instruments discussion forums.

Our motion control cards simplify motion control applications and allow you to develop trajectories which would not be possible to create using a DAQ card.  Furthermore, our motion control drives provide the necessary current and translate the signal from the DAQ card or the motion control card to the signals needed by the stepper motor.  Using your existing hardware may increase your development time greatly.

That being said, it looks like it should be possible to control your stepper motor using the hardware you have described.  My guess is that this phase-polarization algorithm in LabVIEW is being used to generate the four phase-shifted signals you will need for the stepper motor, in leiu of the stepper drive.  Can you confirm that?

There is a Dev Zone document on our website which describes the different signals needed by the stepper motor.  This documents also discusses half-stepping and micro-stepping, so this should give you an idea of what signals you will need to generate to acheive these types of control of your stepper motor.  Here is a link to that document:

Stepper Motor Switching Sequence

This document should be a good starting point for implementing these types of control.  Please reply though if you have any further questions.  Thanks.


Rishee B.
Applications Engineer
National Instruments

[embr13]

Hi Rishee,

Thanks for the response. Yes, the LabVIEW algorithm will be used to step through the phase sequence, by activating the digital output modules in the necessary order. Thanks also for the reference, it will be quite helpful when trying to subdivide steps through microstepping. My only worry is that the digital output/line driver combination I have suggested does not provide for a way to modulate the current; possibly this might be solved using the L6506 current controller from ST microelectronics?

I will first try to get this system running with the existing components, but will keep the NI motion cards in mind if our application exceeds their capabilities.

Best Regards,

embr13

[risheeb]

Hi embr13,

It looks like the L6506 will limit the current to the stepper motor, which would be a good idea, but it will not amplify the signal.  I would suggest that you use it in conjunction with one of the other amplifying chips that are suggested in its data sheet.  It should also work with the L6220 used as the amplifier though.

I hope this helps.  Good luck.


Rishee B.
Applications Engineer
National Instruments