PID on Jaguars is Illegal

[Jon Stratis]

Originally Posted by Kevin Sevcik

So, first and foremost, there's still some reason to use the CAN-bus. You can still offload some functionality to the Jags, such as limit switches, potentiometers, encoders, and current sensing. Yes, your feedback on encoders and other sensors will be delayed, relative to what you'd get on the cRIO, but it is an option.

Actually, that doesn't seem to be the case. Sure, you can hook up encoders and potentiometers, and send those signals, along with current sensing, to the cRio for processing. That's not offloading functionality though - it's just giving you a few more ports to hook sensors into in addition to those provided by the digital side car and analog breakout. But limit switches? Wouldn't <R62> apply here as well:

"...any additional devices on the Ethernet or CAN-bus must not provide command signals that do not originate from the cRIO-FRC."

A limit switch hooked up to the Jaguar would be providing a command signal to stop the motor when it reaches a specific point. In fact, this signal can override the signals sent from the cRio and give you different behavior than the code tells you. If you have an elevator with a limit switch to tell you when it's hit the top, the Jaguar can no longer legally stop the elevator for you - that has to be done in the code. As such, this would seem to disallow hooking limit switches into the Jaguars at all.