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HELP! Cow Town ThrowDown Partcipation in Jeopardy!
OF COURSE... "Murphy's Law" for a rookie team...
Our Victors controlling our arm rise/fall have suddenly stopped being Enabled... we use a PWM splitter from Slot 5 on the Digital Sidecar to command the two Victors that each spin a Window Motor that are combined to move a gear box... Everything was working fine, has been working fine, until a team member pulled the PWM connector (from the Y-side) out of one of the two Victors (connected by the PWM Y-splitter) while they were ENABLED... We have swapped out new cables... but here's the scratch-your-head part, we have five other Victors that work fine (4 CIMS, 1 bane bots gripper motor) and they enable just fine from their respective slots on the DS and when we move the new cable over to these Victors to test, they will SOMETIMES Enable and other times NOT Enable?!! Where's the "flakiness" coming from? We've swapped-out the DS with a new one and have the same problem... Could there be a voltage/amperage problem that causes DS "flakiness"? We get the MOST "flakiness" from when the PWM Y-splitter is attached from one DS slot to TWO Victors?! IF we can't resolve this... I can't see how we can justify driving 14 hours each way from San Antonio to Kansas City... THANK YOU in advance for help! |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
Two questions:
1) Have you removed the locking pins from your window motors? That can cause everything to bind up, causing some things to work one way but not others. 2) Are you sure you're not getting 12V from the Victor outputs? (It's not stated in the original post, so I figure it's worth asking. If you are, I bet it's the locking pins from above.) |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
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We can't get the TWO Victors that drive the TWO Windows Motors to ENABLE... BOTH Victors are connected to Slot 5 in the DS via PWM Y-splitter... |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
First, determine if the problem is with the PWM or with the Victors. Put the robot up on blocks and swap a PWM from a working Jag and move it to one of the questionable ones, if the victor works, your PWM is the problem. Otherwise, your victor is the problem and might need to be replaced. I would venture to say that more likely though, the PWM is the problem. The PWM connections on the Victors are kind of finicky. I find myself needing to unplug and replug the PWM several times to get it to work. Also, make sure that the PWM is pushed in all the way and not resting on a pin that is out of alignment. All of these would cause the victor to not receive a signal from the cRIO and not work.
Hope you get it fixed, Patrick |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
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The "flaky" readout is from the tip of the PWM, not the DS. |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
Michael,
While the buffers on the DSC should be able to handle the removal of a PWM cable it is entirely possible that in trying to reinsert the cable a voltage was conducted backward into the DSC. The PWM cable does carry +5 volts and power common. The +5 volts is used to power the opto-couplers inside the Victors. My first recommendation is to find a new PWM cable and connect it in place of the PWM wiring currently on the robot. If the Victor then enables, you can guess that the 'y' cable or the PWM cables are at fault. If the Victor does not not enable as before, try connecting to a know good Victor. It is unlikely that the Victor could be damaged by pulling out the connector but it possible. I am guessing that you have checked that the PWM cable is fully inserted. These connectors do require some experience to get them fully into the connector body on the Victor. When fully inserted, 1/8" or less of the brown PWM connector is visible above the case of the Victor. Hope this helps. I would bet that the trip would not be in vain as other teams are sure to help you when you arrive. Al |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
Just for the hell of it, try checking the voltage between your frame and any of the negative ports on your PD board. We had a problem last season where we were discharging voltage onto the frame and that F'ed all of the electronics up.
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Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
Al,
We have replaced the PWM cables several times (including the Y-splitter), and we are still getting "flaky results". We also replaced the Victor and the DS, as said before. The PWM cable has been confirmed to be in there. So what we have basically done is confirmed that the PWM cable and the Victor itself is not at fault, and the PWM is fully inserted into the Victor. We aren't sure what is left to troubleshoot at this point; we believe we have narrowed down the problem to either the PWM connected to the DS or the Victor, as when we checked the voltage from the tip of the PWM, it was fluctuating every time. |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
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Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
I would try unplugging everything, from the cRIO to the motor and try brand new components where you can and hopefully in reassembling them you will fix the problem. It also is possible that you have multiple faulty PWM cables. I don't know why but it always seems that we have more that don't work than do work. Also, with the blinking light on the victor, it doesn't change color or pattern when you ENABLE/DISABLE the robot from the driver station right? If it does, it means that the PWM is not the problem, but overcurrenting or something else is going on.
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Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
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As for your first idea of unplugging and putting in brand new components, we are planning on doing this as a last resort if we cannot troubleshoot and eliminate the problem. |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
Look for grounding problems. If you leave out the ground lines to the DSC the PWM can become flaky. I had a team that left off the ground lines because they were not using any power on the DSC. Turns out you need them anyway.
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Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
I also posted on your FB wall. Let me know if you're still having problems, I can probably drive down there Thursday if you need the help or possibly late Wednesday.
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Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
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IF you can come here today... that would be awesome... we'll feed you well... ;-) Please call me if this is something you can do today... THANKS!! 210-858-8575 |
Re: HELP! Cow Town ThrowDown Partcipation in Jeopardy!
To ALL who have replied with advice... THANK YOU, THANK YOU!
We _appreciate_ the time/effort of everyone who contributes to Chief Delphi... hopefully, someday soon we'll be experienced/seasoned enough to contribute advice ourselves... ;-) --Michael Blake |
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