pic: What's weird with this image

[Jonathan L.]

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[jman4747]

Talon SR's are Y-cabled and yet are being driven in reverse of each other... some how?

[Kevin Sevcik]

Looks like someone's been playing with the calibration on those Talon SRs and managed to calibrate one backwards. I don't see a method to get back to default calibration, so you're probably stuck with just re-calibrating them

[Jonathan L.]

Originally Posted by Kevin Sevcik

Looks like someone's been playing with the calibration on those Talon SRs and managed to calibrate one backwards. I don't see a method to get back to default calibration, so you're probably stuck with just re-calibrating them

We tried recalibrating, although we need to try again since I'm not sure they flashed green afterwords. Anyway, we have motors connected to each talon and both motors turned in the same direction. It must be that the internal electronics of one of the talons are reversed at the LED.

[Kevin Sevcik]

Originally Posted by Jonathan L.

We tried recalibrating, although we need to try again since I'm not sure they flashed green afterwords. Anyway, we have motors connected to each talon and both motors turned in the same direction. It must be that the internal electronics of one of the talons are reversed at the LED.

That's a more remote possibility, but possibly true. Unless you have the exact same motors wired the exact same way, they might still turn differently. If a multimeter reads the same voltage when you put the red probe on M+ and the black probe on M-, then I would definitely agree with your assessment.

If it is bad internal LED wiring and the Talon is new, I would talk with Vex, Andymark, Cross the Road, or FIRST about getting a replacement. That LED is valuable for troubleshooting, and if all the fault codes are in flashing green, that's going to be extremely confusing.

[JPBlacksmiths]

I would check your PWMs and make sure both are inserted the correct way

[Peyton Yeung]

Originally Posted by JPBlacksmiths

I would check your PWMs and make sure both are inserted the correct way

But a PWM is signal power ground. It shouldn't work if it is plugged in backwards.

[Taylor]

Originally Posted by Peyton Yeung

But a PWM is signal power ground. It shouldn't work if it is plugged in backwards.

Be careful with shouldn'ts. We have encountered similar issues with backwards PWMs in the past.

[TikiTech]

I agree this is odd.

Does the condition move if you swap the "Y" output on the motor controllers?
As in the motors do the opposite as they are doing now.

Try swapping the y cable to the one used on the other side and note if the condition follows.
Or just swap the "Y" cables on the RoboRio.

Does the condition follow the cable or stays with the motor controllers?

I would make sure when recalibrating not to use a "Y" cable.
And test each motor separately and not on the "Y cable.
If the problem still exists only when on that specific Y cable, its got issues.

This should narrow down the issue to the cable or one motor controller.

Just curious is the voltage output of those motors indeed opposite to each other.

Hope you get this sorted.

Aloha and good luck this season!

[Jonathan L.]

Originally Posted by Kevin Sevcik

Unless you have the exact same motors wired the exact same way, they might still turn differently. If a multimeter reads the same voltage when you put the red probe on M+ and the black probe on M-, then I would definitely agree with your assessment.

We did not check with a multimeter so that is a possibility.

Originally Posted by TikiTech

I agree this is odd.

Does the condition move if you swap the "Y" output on the motor controllers?
As in the motors do the opposite as they are doing now.

Try swapping the y cable to the one used on the other side and note if the condition follows.
Or just swap the "Y" cables on the RoboRio.

Does the condition follow the cable or stays with the motor controllers?

I would make sure when recalibrating not to use a "Y" cable.
And test each motor separately and not on the "Y cable.
If the problem still exists only when on that specific Y cable, its got issues.

This should narrow down the issue to the cable or one motor controller.

Just curious is the voltage output of those motors indeed opposite to each other.

We did swap the PWM cables between the talons and on the roboRIO. The problem always stuck on one of the talons (I believe the one on the right of the image).
As I said before, the direction of the motors was the same. We did not test the voltage yet, however.

[Tom Line]

I bet one of the leds is burned out. We have a similar issue, but ours is always green on an old one. Does that one ever turn green?

[Jonathan L.]

Originally Posted by Tom Line

I bet one of the leds is burned out. We have a similar issue, but ours is always green on an old one. Does that one ever turn green?

This is always backward of what the signal is. When we say forward, it turns red; When we say backward, it turns green.

[JamesBrown]

Originally Posted by Kevin Sevcik

That's a more remote possibility, but possibly true. Unless you have the exact same motors wired the exact same way, they might still turn differently. If a multimeter reads the same voltage when you put the red probe on M+ and the black probe on M-, then I would definitely agree with your assessment.

If it is bad internal LED wiring and the Talon is new, I would talk with Vex, Andymark, Cross the Road, or FIRST about getting a replacement. That LED is valuable for troubleshooting, and if all the fault codes are in flashing green, that's going to be extremely confusing.

Originally Posted by Jonathan L.

This is always backward of what the signal is. When we say forward, it turns red; When we say backward, it turns green.

Seems entirely plausible to me that the LED was simply installed backwards. Bi Color LEDs are (usually at least) 3 pin, with the center being the common Cathode, and pins 1 and 3 being the two different anodes. It would be a pretty simple mistake to install the LED 180 degrees out and have the colors reversed.

[ratdude747]

Originally Posted by JamesBrown

Seems entirely plausible to me that the LED was simply installed backwards. Bi Color LEDs are (usually at least) 3 pin, with the center being the common Cathode, and pins 1 and 3 being the two different anodes. It would be a pretty simple mistake to install the LED 180 degrees out and have the colors reversed.

No, actually they do make two pin bi-color LEDs. The color is determined by the direction of current (so the anode of one color is the cathode of the other and vice versa). IIRC this used to be and still may be common, as they are particularly useful for driver circuits involving OP-AMP voltage comparitors; they still work for digital circuits too (if run between two outputs, one used to source, one used to sink).

That said, once again, a backwards LED would still have the same result. However, I'd think these were machine assembled which would mean that the error would have to be with the component itself (either in the reel tape backwards or somehow assembled wrong at the LED fab).

Either way, I'd consider that to be DOA and grounds for a warranty exchange.

[Hgree56]

The one connector is a different shade of yellow.