Re: [CAD_CAM_EDM_DRO] Encoders

Thanks Jon,

Am I right in thinking then, that the quadrature output is only on 2 wires,
probably in this case the brown and the white and that the voltage on them
will swing above and below some central point to indicate the four states.
I'm having difficulty visualising exactly where I should be monitoring the
signals. As all the reds are connected together (I can see this as tracks on
the pc-board) and the blacks also appear to be electrically connected, that
only leaves brown, white and green, each of which has one of the reds
adjacent to it. So, if I put 5volts across the red and black, do I monitor
the voltage between say, brown and black or brown and red, or perhaps brown
and green?

Ian
--
Ian W. Wright
Sheffield UK
www.iw63.freeserve.co.uk

----- Original Message -----
From: "Jon Elson" <elson@...>
To: <CAD_CAM_EDM_DRO@yahoogroups.com>
Sent: 27 August 2001 19:09
Subject: Re: [CAD_CAM_EDM_DRO] Encoders


> Ian Wright wrote:
>
> > Hi,
> >
> > In a previous post I mentioned that I have acquired a couple of old
> > plotters - well, one of them is now less than its previous self and the
> > motors, controller etc., are sitting on the bench in front of me.
> > The encoder bit of the motors has a 10-way ribbon cable coming from it
and I
> > have attempted to trace the wiring - not too successfully. There appear
to
> > be 4 black wires which are all connected together electrically (as far
as I
> > can see with my ohmmeter) which I presume are groungs, 3 red wires which
are
> > also electrically connected which I assume are +5v (I know these are
> > connected to the LED which shines through the encoder disk via a 120 ohm
> > resistor). There are also 3 other wires, brown, white and green which I
> > assume are the outputs. On the small PC-board inside the encoder I can
see
> > through plated holes marked A+, A-, B+, B- but I can't trace where they
are
> > connected to as they dissapear under the encoder disk, they certainly
aren't
> > connected directly to any of the output wires.
> > So, without having any 'serious' test equipment, is there any way I can
> > determine what the various wires do and what the encoder count is (for
> > preference without having to take the encoder disk off and count the
lines
> > by eye!) ? If it's any help, the colour sequence is:-
> > brown, red, white, red, black,black,black,black,green, red.
>
> if you still have the rest of the plotter, you may be able to get more
> info from looking at that, too. But, if you know the +5 and gnd. then you
> can power the encoder and use a meter to figure out what the other
> signals are. it may have the A and B quadrature channels and an index
> channel that was unused by the plotter.
>
> You can count the cycles of the encoder with a meter that beeps.
> If you get 50 beeps in one revolution, then that encoder would count 400
> quadrature transitions per rev.
>
> Jon
>
>
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