NetNews Usenet Archive 1992 #31/NN_1992_31.iso/spool/sci/electron/21320

Internet Message Format | 1992-12-22 | 1.6 KB

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Newsgroups: sci.electronics
Subject: rotary encoders
Message-ID: <[e-mail]>
From: [e-mail]
Date: Mon, 21 Dec 92 22:55:26 GMT
Organization: Industrial Research Ltd., New Zealand.
NNTP-Posting-Host: grv.grace.cri.nz
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Thanks to all those who have responded so far, I'd like to clarify my
needs a little.

The advantage of the Grey code is that there is only one bit change
/transition per step of resolution so there is no ambiguity during
the transition stage as would exist with straight binary coded
systems.

The advantage of an absolute encoder system over a relative system
is that the encoder does not have to be zero'd after a power cut etc.
This would be a problem with any system which must recover from a
power cut etc and must know exactly where it is at when power is
restored such as a sequencer. Another example is a wind direction
indicator which will nmot conveniently rotate on demand.

The disadvantage of absolute systems is the number of sensors and the
complexity of the encoding disk.

I've developed what I think is an alternative which has a much simpler
disk, and I want to do some comparisons with a grey-coded system. To
do this I need to generate some grey code sequences for given angular
resolutions - remember the last code must run into the first (cyclic)

I'd also be interested in _any_ other absolute code methods around,
I've never found any in 18 years of electronics :)

Thanks again for the responses

regards
Bruce