Re: [Emc-users] Encoders

[Steve B. <st...@pi...>]

On Fri, 02 Oct 2009 15:24:24 -0400, you wrote:

>Page 5 and 6 show it but not at a good time scale, page 7 from the base 
>thread sample shows it very clearly Steve.  Noise.  Until that is gone (and 
>encoder A output could have a closer to 50% duty cycle too, I'd almost return 
>that one in fact if its sealed and non adjustable), it isn't going to work, 
>not even if we make sacrifices. :)
>
>I have to assume the encoders cabling is shielded, and the shield ends at the 
>encoder so there is no connection via the shield to the machine by way of how 
>the encoder is mounted and driven.  That would be what we call a ground loop, 
>and that is usually a no-no. 

Thanks Gene, that gave me clue and I found it - The encoder cable had a
strand from the shield touching the plug at the controller end. Much,
much better now, but still has the odd glitch, from where I don't know.
disconnecting all the grounds didn't get rid of it.

As for the 50% duty cycle, can't do anything about that other than
replace the encoder.

But - running at slow speed it's MUCH better, and running my test 1.5mm
pitch test file at my normal 700 rpm it's not noticeable at all.

Have a look at the difference :)

http://filebin.ca/brcenc/encoder.pdf


Steve Blackmore
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