Why are Limit Switches outlawed with PWM, but not CAN?

[Al Skierkiewicz]

Originally Posted by PhilBot

We've established that regardless of the control method you are using with the Jaguars (CAN or PWM), the Limit switch inputs perform the same control function... that is: they stop the motor running a specific direction if that limit switch circuit goes open-circuit.

The only difference between the two interfaces is that CAN ALSO lets the cRIO read the state of the switches,

Phil,
I am not a programmer so tender my answer with that. It is my understanding (from inspector training) that in the CAN implementation, the state of the limit must be read, passed on the CAN bus to the Crio which then generates motor command. Under FMS the Crio is controlled and the limit switch based commands are then enabled or inhibited by the FMS command. It is for this (and others) reason that we went through several firmware revisions in that first year. As each revision was released, it was necessary to determine that any and all motion could be stopped by the FMS. If it could not, then another release was generated. The safety of the participants, volunteers and field are still the highest priority in making decisions about the control system.

Please ask the Q&A so everyone can be satisfied.