CAN Rules

[Joey1939]

R61 The PDP CAN interface must be connected to the CAN-bus on the roboRIO (either directly or daisy-chained via another
CAN-bus device).

I am reading this correctly that every team is required to use CAN?

Also, R40 defines acceptable positive and negative wire colors, but I see no rules that define CAN wire colors.

[cgmv123]

Originally Posted by Joey1939

I am reading this correctly that every team is required to use CAN?

Correct. Don't be afraid. This is a different implementation of CAN than in the past.

Also, R40 defines acceptable positive and negative wire colors, but I see no rules that define CAN wire colors.

CAN wires are signal wires. No signal wires have color requirements.

[RufflesRidge]

Originally Posted by cgmv123

CAN wires are signal wires. No signal wires have color requirements.

Though the green and yellow wires in your kit will match the coloring on the connectors so that may be a wise choice.

[cgmv123]

Originally Posted by RufflesRidge

Though the green and yellow wires in your kit will match the coloring on the connectors so that may be a wise choice.

Of course, but virtually the entire control system uses the Red:+, Black: - convention, and you could use White:+, Blue - if you wanted to.

[jnicho15]

It is a differential pair, not signal and ground. It should be a twisted pair.

[adciv]

It should be twisted, but does not have to. During beta testing, we were running it using non-twisted to a worse case than using twisted, no issues.

[protoserge]

If you want to twist your own cable...

https://www.youtube.com/watch?v=YAquFszYZ1k#t=75

[Al Skierkiewicz]

It is not really a "balanced" signal but it is a transmission line. You will need CAN enabled if you wish to use the pneumatics PCM module and turn on your compressor. As always, CAN implementation requires a terminating resistor at each end of the buss. One is provided in the RoboRio (The start of the buss) and another is provided in the PDP (possible end of the buss). If you wish to configure your CAN wiring differently or not use the PDP CAN, then be sure to provide the required termination resistor at the last device in your chain. The majority of CAN problems in the past have centered around the termination resistor.

[Joe Ross]

Originally Posted by Al Skierkiewicz

If you wish to configure your CAN wiring differently or not use the PDP CAN, then be sure to provide the required termination resistor at the last device in your chain.

Per R61, PDP CAN is required.

[Al Skierkiewicz]

Thanks Joe, I forgot we included that. This gives the battery voltage reported by the PDP, right?

[martin417]

Originally Posted by Joe Ross

Per R61, PDP CAN is required.

Just to avoid confusion, CAN to the PDP is required (and to the PCM if you use pneumatics), you can still use PWM for motor control.

[nixiebunny]

CAN is required to talk with the PDP, but the upside is that you get to learn what all your load currents are!

[Joe Ross]

Originally Posted by Al Skierkiewicz

Thanks Joe, I forgot we included that. This gives the battery voltage reported by the PDP, right?

The battery voltage is monitored by the roboRIO. I assume the PDP requirement is so the DS and/or field can monitor currents.

[marshall]

Originally Posted by Joe Ross

The battery voltage is monitored by the roboRIO. I assume the PDP requirement is so the DS and/or field can monitor currents.

Correct.

[duane]

The 4 ft of green/yellow wire is enough for some short runs for PDP and PCM connections. We plan on using CAN elsewhere as well.

I have not found a good source for green/yellow twisted pair. I know it doesn't have to be the same color, but it's good consistent reminder and it's our school colors. :-)

Does anyone have a good source for the green/yellow twisted pair wire?

Thanks