Re: encoder

--- In CAD_CAM_EDM_DRO@yahoogroups.com, GRautoHP@a... wrote:

> HOW CAN I TELL IF MY ENCODER IS A QUADRATURE TTL OR NOT?
> IT HAS
> CHAN
> A+
> A-
> B+
> B-
> MARK-
> MARK+
> DC GROUND
> +5 VDC
>
>
> [Non-text portions of this message have been removed]

The +5 tells you it is TTL compatable. This is a differential output
with separate - outputs on each channel. telling if it is a true
quadrature signal requires the use of a dual channel scope but most
likely it is a quadrature output. The "mark" is an index output that
is not quadrature and marks a complete revolution of the encoder (it
may have multiple ticks per rev but probably only one).

If you want to have some fun, hook an led with a 330 ohm resistor in
series with the anode to A+ and the cathode side to A-. Now do the
same with B+ and B-. Apply +5 regulated to the +5 and ground of the
5 volt supply to DC GROUND. Slowly turn the shaft. There should be
four different states for the LED's: A on B off, A on B on, A off B
on, and A off and B off. If the count per revolution is high you may
not be able to turn it a small enough increment to see the distinct
states. A 500 count encoder has 2000 distinct changes per revolution
which means you only have to rotate the shaft .18 deg to get a
transition!

In single ended (like on a Gecko) operation the A- and B- would both
be tied to ground and the signals taken from A+ and B+. If you
wanted to use these in a high noise situation with long leads the
differential output can be feed into a differential to single ended
chip (forgot the number) at the receving end and increase the noise
immunity.