I threw this together to hopefully help others understand the legal methods to wire their robot radios for this competition season:
Hopefully it helps others given the questions that have come up in the Q&A about legal robot radio wiring.
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- Option 1
- Option 2
- Option 3
- Option 4
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And the ZebraSwitch is still a legal option to get additional Ethernet ports!
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Option 2 and 3 people, I love your energy. What led you to this configuration?
I transferred for the season when normal team had to cancel, so not 100% sure on what the decision process was, but my understanding is as follows:
Getting the extra motors the PDH allowed was the biggest advantage for us this year. This meant we just went for the PDH since the VRM works as well as ever, and we only had 3? solenoids max in the original plan so no real need to upgrade the PCM (and they’ve since been dropped to boot).
4 and half of 3
Option 3 is what we are considering switching to. Not having the ability to run redundant power when using the Radio Power Module is a huge downside, and makes the RPM useless imo. I’d love to move away from the crappy POE injector cables, but until we are allowed to use redundant power with the RPM, it may be option 3 for us
Wait so it isn’t legal to vrm to barrel connection and use the rpm?
Thanks for the picture! It’s going into my inspection kit.
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It is not and I would not recommend doing it. The VRM is 12 Volt out where as the RPM is 18 Volt.
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If the radio isn’t wired to the VRM (it is wired to the RPM), and we need the VRM anyway for a network switch, is it fine to wire the limelight to one of the 12V2A channels?
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Do you run redundant power to any other control system items on your robot? Has your team ever seen a power problem when powering your robot over just POE?
I understand how teams got to the point of redundancy wiring on the radio, because the old standard practice was just the barrel jack until the POE option became available and the cost and action of doing so is so low (just run one extra wire), but I disagree that it is required and “makes the RPM useless”
From our testing there is zero reason to do redundant power wiring on a radio when powered over POE.
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Money. We were forced to go to the REV PDH because of the number of motors we need, driven partially by swerve drive. However, we have many CTRE devices laying around, so paying for the Rev radio power thingy simply didn’t enter into the conversation.
If we hadn’t had our hand forced, we would have used the CTRE power distribution panel.
Unfortunately we have experienced problems with our radio when not adding a barrel jack redundancy pathway.
Our process usually is hot glueing the ethernet cable into the radio after we flash our radio at a tournament, and hot glueing the barrel jack into the radio as well.
To answer your question of using redundant power to power any other control system on the robot - the answer is no. But for a few reasons:
- Most other control systems on the robot can fail temporarily and our robot still can function. Example: Limelight. We power the limelight over POE, and don’t have redundancy. If the limelight dies, unfortunate but manual adjustment still works
- The radio takes 40 seconds to reboot even after a blip in power. Until we get a better radio, I can’t justify that risk of our entire robot dying because our ethernet cable wiggled around in the connector. I’d love to be able to stick a bigger capacitor inside the radio for situations like this.
So honestly I have no issue with the RPM whatsoever. My issue is with the radio, and the ruling that we aren’t able to use redundant power
Same. We had radio re-boots due to POE shaking loose during matches before adding extra reinforcement - I think all we had was tape. We went to redundant power and haven’t had the issue since.
I mean, you can… but why would you? The limelight has a built in regulator that will keep it powered just fine.
Basically only to save a PDH port – if we’re wiring the VRM to the PDH anyway, we don’t have to use an additional port for the limelight.
It may help that you can use a really high quality Ethernet cable now (with RPM), but the option to dual power would still be nice. It would be OK if this required a VRM (or equivalent). My personal sense of things is that the radio is often the weak link, exacerbated by the long recovery time after even a brief power event. So, a better radio would be a big win.
Nice. The PDH drawing on Rev’s site may confuse people, as it shows the VRM connected to 19 since it is not used to power the radio in the drawing. If the radio is powered by a VRM it needs to be on PDH 20-21 per R617B
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Are you able to provide details regarding the testing you did?