At 12:14 28/01/98 -0000, you wrote:
>Many thanks for everyone who has helped me with this subject....
>
>After having a good look at the HCTL2016 chip... I think I can do the whole
>job with it alone (ok one for each stream...)
>

        There's also the LS7166 it's a quadrature decoder and 24 bit Up/down cou
nter
and a count frequency up to 10 Mhz !!!
        I'm using these chips with a 2048 pulses per rev. encoder (8192 position
s
in X4 mode),
a 16F84 control the chip and send the data in a RS485 line.
        To test if the chip lose a count, i've attached an elastic line (1 meter
in length)
to the encoder axle and played like a guitar, I'm unable to lose a count even
pushing the line hard !!!


>I have a 24bit wide I/O card for my PC with which I can drive the 2016s... A
>two chip solution!!!!!!
>
>The only problem I can see is the distance from the encoders to the PC...
>about 30 feet!!! If I put the 2016s right by the encoders then I hav a long
>parallel cable... Not good! But if I put the 2016s next to the PC then I
>have long leads carrying the quadrature signals... Very noisy.... Any
>ideas???

        You can do a decoder board with the 2016 or LS7166 and control it with a
 PIC
and send the result in a serial line RS232 (RS485 if using more than one
encoder)
        Another solution is to use the encoder with 2 MAX485 and another 2 on th
e
I/O card in a RS485 like aproach.

        You can get the LS7166 datasheets on http://www.usdigital.com

Hope this Helps

Ricardo Seixas