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Unread 28-01-2009, 10:04
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Kevin Sevcik Kevin Sevcik is offline
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Re: No compressor control

Quote:
Originally Posted by Mr. E View Post
so...He's really just plugging the pwm cables to the digital side car? In the open Vi, is there a "module 4," or is he making his connections in the labview program to the digital inputs and relays?
In the past we have always wired the black and white wires of the pwm to the pressure switch. Should this still work?
It will work perfectly well. It will also be illegal. <R61> is most applicable:
Quote:
<R61> Every speed controller, relay module, and servo shall be connected via PWM cable to the Digital Sidecar, and be controlled by signals provided from the Mobile Device Controller via the Digital Sidecar. They shall not be controlled by signals from any other source.
To the best of my knowledge, it has always been thus. I'm surprised you've been passed through inspection with that setup on your robot in years prior. I'm also surprised no one noticed your robot merrily pumping away on the compressor while it was disabled...

EDIT:Also, to Peter H,
If you've updated to the lastest version of the WPI libraries, you shouldn't have a "Run" vi for the compressor. There should be a "Start" vi. You only have to execute this vi ONCE. The "Open" vi spawns a completely separate process that runs in its own loop. The "Start" vi instructs this process to start running the compressor whenever it sees the pressure switch close. The "Stop" vi similarly tells this process to stop running the compressor. And the "Close" vi both stops the compressor and kills this process.

You're not hurting anything if you're executing the "Start" vi in every loop.... but you're wasting some small amount of processor cycles that you don't need to.
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Last edited by Kevin Sevcik : 28-01-2009 at 10:21.