Quote:
Originally Posted by Al Skierkiewicz
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.
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The limit switch functionality is independent of commands; there is no way to override the limit switches in software.
There is a "Soft Limit" feature that uses the encoder or potentiometer to read the position, and stops the motors at a user defined position. However, motor movement will still be stopped by the hardware limit switch opening the circuit, even if it hasn't reached the soft limit yet.
When using CAN, it is entirely up to the user to read the limit switch states from the Jaguar. The cRIO does not issue motor commands based on the limit switch states. The cRIO issues standard commands and the Jaguar follows them to the best of its ability. If the cRIO is telling the Jaguar "move forward!" it will try to. If, however, the forward limit switch input is open-circuit, the Jaguar will not move forward, despite the cRIO continuing to send a forward command.
Quote:
Originally Posted by Al Skierkiewicz
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.
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The multiple Jaguar firmware updates last year were to fix bugs (a power-up bug, PID bugs, etc.), none of which had to do with the limit switches or the FMS. Actually, the FMS doesn't ever talk to a Jaguar; it tells the cRIO "Disable!", the cRIO stops sending motor commands, and the Jaguar times out.
-David