PUMA 560 servo motors must be configured as stepper

[GTPUMA]

Hi,

I'm using an NI PCI-7350 on a servo motor that originally came with the PUMA 560 arm. My concern is that I am not able to drive the motor in my VI when the motor is configured as servo, only as stepper. Unfortunately I haven't come across any official documentation for the motor itself (only pin out and limiting spec.s), all I can find officially is that the motor is DC brushed type. In addition, using software limits on the drive has no effect. What can I do to rectify this?

The MAX configuration file, and VI is attached. Please open the 'singleAxisDemo' VI, RampFinal is a subVI within this.

Thanks!

Tomas

GTPUMA Senior Design Group

Georgia Tech Electrical and Computer Engineering

[Tim_O1]

Hi GTPUMA,

I am not exactly sure what is causing your issue. Are you sure this is a servo motor? What other hardware are you using (motor drive)? When you have it configure as a stepper motor, does everything function correctly? If not please elaborate. You might want to get in contact with the manufacturer to get real documentation on the motor. Do you see any difference when trying to move the motor in MAX?

Tim O

[GTPUMA]

Oddly enough, when I do the 1-D interactive test in MAX configured as stepper the motor doesn't drive at all but the VI we wrote is able to drive the motor. However, in the VI the software limits don't seem to function at all and the Find Reference VI's don't ever succesfully move the motor to its home position (see attached updated code).

When the motor is configured as servo we are able to test the motor in MAX (although its behavior seems to be the same no matter what the test parameters are) but our VI is not able to drive the motor at all.

By the way we are using a TA115 motor driver in current mode (see attached specs).

Any chance we could speak over the phone? I'm sure we could get a hold of a contract that GeorgiaTech holds with National Instruments if required.

Thanks!

-Thomas of GTPUMA

[Tim_O1 · Accepted solution]

Hi Thomas,

Do you have your limits enabled in MAX? Do the limits work in MAX? If you motor is working in MAX and not LabVIEW there could be something wrong with your code. To test your motors in LabVIEW please refer to the examples under Help>>Find Examples…>>Hardware Input and Output>>Motion Control>>NI 73xx. Do the examples work in LabVIEW? If not you might have something wired up incorrectly.

You can reach our technical representatives at 800-531-5066 or you can go to ni.com/support and click Contact an Engineer if you have a support contract.

Tim O

[GTPUMA]

Found the problem! It turns out that we had the two analog outputs to the motor reversed at some point in the wiring, causing the motor to turn the opposite direction than was expected which caused the feedback to fail.

Why the VI I was using would only work in stepper mode? I have no idea, but the VI was written by a previous group and we have found that there is other problems with the code and we are therefore discontinuing use of it.

Thanks for your help!