Running the Labview Example CAN Talon Code

[btcshields6]

I have an E4P hooked up to the Talon SRX via modified talon connector cable (see blurry attached pic). When I move the slider, the motor visibly and audibly speeds up, but the actual speed line on the graph does not move to meet the set motor speed line. I also have attached a picture of the self-test from the NI Web Viewer that I took while the motor was running.

The same thing happened when I tested the Versa Planetary Integrated Encoder on a gearbox. The motor changes speed, but the actual speed line does not move.

[Alan Anderson]

The web information suggests that the encoder itself, or the wiring to it, is not working. As you turn the shaft where the encoder is mounted, do you ever see the A input as anything other than 0, or the B input as anything other than 1? If one or both is stuck, the SRX position count won't change.

[btcshields6]

Okay. When I first had trouble with this example, I used a multimeter to check the resistance of each wire, confirming that we fused the wires correctly. Also, when the encoder is plugged in, the LED lights up.

I suppose that the encoder is most likely damaged. The LED may light up anyway.

I'll check the counts for A and B tomorrow.

So those Versa Planetary Integrated Encoders came in a few days ago. I hooked them up and tried them out using this same example (I opened the block diagram and made sure to change the encoder type to the correct one). I didn't have to fuse any wires, since the SRX Cables plug directly into the Integrated Encoders.

As with the E4Ps, the speed can be heard and seen to change, but actual speed does not change on the graph. Also, the LED on the encoder is yellow, as the manual states it should be during normal operation. I don't know why there would be an issue with these.

Thank you.

[btcshields6]

The E4Ts we're planning on using on the final robot came in today. I mounted one on my test motor. This time I did see actual speed register. But the slider was hardly in control. As I adjusted it the motor oscillated quickly from the -5000s to the 5000s. I figured this might be an issue with PID tuning (P is 1, I is 0, D is 0, Feed Forward is .01), but adjusting P just made the issue happen later in my sliding. I tried values of P between .1 and 2.

Once the oscillation starts, and will not stop when I return the slider to 0. Any suggestions?

Thanks,

Benjamin

[Alan Anderson]

Originally Posted by btcshields6

As I adjusted it the motor oscillated quickly from the -5000s to the 5000s.

That sounds like your feedback is opposite of your control. Use the "invert sensor" option. (I don't have LabVIEW available at the moment, so I don't know exactly what it's called in the example.)

If you don't have much load on the motor or inertia in the system, you will find it to be very difficult to get it to stabilize. If you can limit the motor power's rate of change, doing it will help a lot.

[ozrien]

I recommend that LabVIEW teams look at the Speed Servo example covered in the Talon SRX Software Reference manual, which has a complete walk-through and example VIs for almost every sensor type. Its more comprehensive than the Speed Example that comes in with the LabVIEW installer.