Hello from Team 2102!
We are wondering about compatibility between the new REV Robotics electronics hardware (PDH, Mini Power Module, Radio Power Module, Pneumatics Hub) and the old CTRE/VEX hardware (Power Distribution Panel, Voltage Regulation Module, Pneumatic Regulation Module). Feel free to post any experience with using these together.
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They are all compatible with each other.
Mini Power Module, Radio Power Module, and Voltage Regulator Module have no communications protocols (other than the Ethernet passing through the Radio Power Module obviously) and thus really couldn’t be “incompatible” with anything else as long as it is providing the expected voltages.
The Power Distribution Hub/Panel and Pneumatic Hub/Panel each communicate over CAN to the roboRIO, and as such would also all be inter-compatible.
Two other important questions do come to mind though. 1) What restrictions could FIRST put on the mix & match, which this past year I don’t think FIRST had any restrictions outside of being unable to also use the barrel jack on the Radio if using the Radio Power Module, unlike if using the Voltage Regulator Module where you could have both PoE and Barrel Jack. 2) What code differences are required between the two, which the WPILib outline here for Pneumatics Operating pneumatic cylinders — FIRST Robotics Competition documentation and here for Power Distribution Power Distribution Module — FIRST Robotics Competition documentation for Java/C++ (I don’t know an equivalent for LabVIEW).
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They have different addresses on the canbus for the modules that uses canbus. Other than that they don’t really interact with each other. So along as it is withing the rules, you can mix and match. I.e. you would not be able to use a PDB and a PDH because you can have only one but you could have a PH and a PCM. I don’t speak for the GDC, but given the supply chain problems I expect both REV and CTRE products will be legal next year.
We have experienced issues running Rev Motor Controllers through a CTRE CANivore can loop.
Correct, that is not supported. The REV motor controllers are CAN 2.0, the CANivore is CAN FD.
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Supposedly REV is developing their own version of CANivore to work with CAN 2.0 but it’s not very likely to be here in time for this year. I know we use NEOs and it has us concerned about CAN usage if there are a good number of motors needed other than drivetrain which were testing swerve and the added motors there. To be honest I’m not a programming mentor and don’t know a lot about that.
From what I understand is that you could use a CANivore for just the CANcoders to lessen the load on the rest of the CAN
I’d probably go with non CAN connected encoders rather then pay $299 to reduce CAN utilization by 8%.
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It’s also my understanding that Spark Maxes use a lot less CAN bandwidth than Falcons by default. We had 16 Spark Maxes and two Cancoders in 2020, and we were not pushing the bus limit.
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Does anyone know if either REV or CTRE is open to working on a CAN standard together (or REV adopting CAN FD)?
CAN FD requires a hardware change. IIRC the new control system components could support it, but the Spark Max could not, and would require new devices to support FD.
This is correct. Greg Needel was asked in a thread a couple months ago about it and he said the hardware in the sparkmax is what doesn’t allow the compatibility and it wouldn’t be feasible to make a redesign. I did a quick search for the thread but couldn’t find it.
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