Controlling a 24V .2A motor

[Bob_Y.]

I had no answer on getting a MID-7654 to control a 24V, .2A servo, so I thought I would ask it a different way.

Is there any way at all to control a 24V, .2A servo through LabVIEW? I have found quite a few sites with stand alone controller/drivers, but I have not run across anything that will work for controlling this with labVIEW. Granted I could probably control one of those stand alones with serial commands, but I think that may be too slow for my application.

Another idea was to use a UMI-7774. Will the UMI-7774 do it alone or do I still need a driver/amplifier. If I do, any suggestions as to which one?

As you might have guessed, motion control is very new to me and this servo was requested by my customer, so I need some help making it work.

Thanks,
Bob

Message Edited by Bob Y. on 05-17-2005 04:14 PM

[Jochen]

Bob,

you could control the 24V motor with the MID-7654 by adding inductances in series to the coils of the motor. Ideally the inductance should have the same ratings like the coils in your motor. This inductance would act like a inductive voltage divider but of course the drawback is the fact that 50% of the power is wasted in these additional inductances.

Probably a 3rd party drive would be a better solution. The UMIs are active breakout boxes for 3rd party drives and they add filtering and isolation but they don't drive power by themselves.
A lot of our customers use 3rd party drives in combination with NI's motion control boards. Typically those drives provide a command input (-10V to 10V) to connect to motion control devices like the NI-73xx boards. The serial port is used for drive configuration.

You might also have a look at our Drive Advisor. Here you can find a list of drives that have been tested with NI motion control boards. Some of them provide also direct connectivity to NI-73xx boards without the need of a UMI. I point out explicitely that there are many many more drives available that are not on that list but that work also perfectly with our boards.

Best regards,

Jochen Klier
National Instruments Germany

[Bob_Y.]

Here are the motor specs:
Voltage = 24 Vdc
Current = 0.2 A
Inductance = 1.19 mH
Resistance = 54.6 Ohm

If I were to add series inductance to reduce the overall power to the device, would I also need series resistance to divide the voltage? And since my current rating is about one fifth of the minimum, I think that I would need to not just divide the current in half but by one fifth.

And the series resistance has me worried about power dissipation in my device.

Thanks again for any help,
Bob Young

[Jochen]

Bob,

I think the motor specs are too far away from the specs of the MID. There could be a way to work with inductances but I think a 3rd party drive would be a much better choice.
NI doesn't claim to be able to drive every single type of servo motor with the MIDs and in this case we only could provide bricolage.

Best regards,

Jochen Klier
National Instruments Germany