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Unread 03-03-2004, 13:05
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Re: Speed Controller brake/coast setting

Quote:
Originally Posted by steven114
Is it possible to control the brake/coast setting on the 884s with the digital out pins? I didn't want to try anything, as I believe a 1 is +5v. Will I damage anything by using this to select between brake and coast on the fly?

Thanks,
Steven
This question was answered in the Q&A today (ID: 893):

Quote:
Q: Can a digital output of the Robot Controller be connected to the B pin of the Brake/Coast selector on the Victor 884 in order to control the Brake and Coast functions of the Victor?
A: No. There are possible ground loop problems associatedwith this approach.
Unfortunately, the answer is no. You can’t legally wire a digital out to the Victor, but it might work. Ground loop problems are tricky and usually produce noise. They usually occur in audio/video systems.

You could probably stare at Victor 884 and RC schematics for hours debating about whether a ground loop problem would exist. Basically, the digital out current leaves the RC and must return to ground through the Victor (instead of the RC), thus creating a ground “loop”. This could possibly be solved by connecting the ground pin of the digital out to the A pin (which is grounded) of the Victor, but this depends on the internal wiring of the Victor and could produce problems of its own. It really doesn’t matter. FIRST said we can’t use this method and that is all that matters.
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