Question regarding R48

R48 states:

All circuits, with the exceptions of those listed in R53 and R55, must connect to, and have power sourced solely by, a single protected 12VDC WAGO connector pair (i.e. the Load Terminals, as shown in Figure 10‑9) of the one (1) CTR Electronics Power Distribution Panel, not the M6 cap screws.

R53 an R55 state that the RIO needs to be connected to the 10A slot and the radio needs to be powered by the VRM.

So crystal clear then - nothing other than the radio can be powered by the VRM, and all devices need to be connected with either the 30 or 40 amp terminals on the PDP. Or so you’d think? But in the FRC Q&A someone who asked a similar question got the following response:

R54 restricts the use of the 12V 2A terminals of that VRM, but does not prohibit using the other terminals on the VRM for other purposes.

This is very confusing as the language of R48 seems to specifically prohibit devices that aren’t the radio from being powered by the VRM. Can someone explain this? We currently have our vision coprocessor plugged into the VRM and we’re not sure if we need to redo the wiring somehow.

The only thing you can’t do with the main VRM is put something else on the 12V2A rails. Each of the other three outputs are allowed to be used.

The VRM has four buck/boosts internally, each one splitting out to two pairs of Weidmuller connectors. To put it another way, the 12V2A buck/boost can only be used for the radio.

I think you may also be conflating the terms PDP and VRM. The PDP is the main distribution block that has breakers slotted into it. The VRM is the smaller brick that produces regulated power.

I know the difference between the two devices but the rule seems to state that all devices have to plug into a 12VDC WAGO connector of the PDP.

All circuits… must connect, and have power sourced solely by, a single protected 12VDC WAGO connecor … of the one CTR Electronics Power Distribution Panel

(Also, I just realized that I accidentally made a typo where I said devices had to be plugged in to the 30/40A breakers on the VRM. oops :confused: )

Your interpretation would also prevent powering any sensor or servo from the roboRIO. That doesn’t seem like the intent (especially given the Q&A answer cited).

what the rule is saying is that all power must pass through the PDB, you can power items off the RIO and VRM ( given their power draw is low enough), as well as custom power circuits( as long as they comply with other custom circuits rules), because the original power source is through the PDB, this rule is to prevent teams from directly connecting items to a non breaker-ed power source or directly to the battery circuit. NOTE: there are exceptions now for battery packs to power cameras, etc.

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Ah, that makes much more sense. Thanks for the answer!

For the most part I would argue that most circuit are powered from the the PDB wagos for most things. Granted that really doesn’t count for items powered off the Rio, PCM, VCM for the radio or battery packs allowed by R40. I would say you are correct in a literal context. Granted that no robots have been inspected under this years rules, and last years rules don’t apply. But R48 has never been interpreted the way you are. (In other words you can power things of the circuits mentioned.) You can always ask Q&A. They are the only official source outside your event’s LRI, It would be interesting to read Q&A’s reply… Just make sure your question is ask in a format that they will give a real answer to.

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