Re: [CAD_CAM_EDM_DRO] Pacific Scientific Servo Motors and Drives

Chris Bruno wrote:

>I recently sold my Mill/Drill CNC setup that I had built with
>steppers and have now finished the rebuilding of my Bridgeport so I
>am finally going to start upgrading it to CNC.
>
>I've managed to score some Pacific Scientific Servo Motors and Drives
>of the PC800 variety and I was hoping that someone on the list may
>have some experience with them. I've printed out the manual on line
>and it suggests that the input can be setup for Step/Direction, but
>when I load the software I cannot seem to get that choice as part of
>the setup routine. The 'default', if I'm understanding things
>correctly, is +/- step so my fallback is to make an interpreter to
>change the step/direction to +/- step. I think someone posted a
>schematic for that within the last few months, but I can't seem to
>find it...
>
>

This is really simple. You take a gate package, such as the 74LS00 and
use 3 gates for each axis.

Direction signal goes to pins 1, 4 and 5
step signal goes to 2 and 10.
pin 6 is wired to pin 9
a negative-going step "one way" pulse comes from pin 3
a negative-going step "the other way" pulse comes from pin 8.
Ground pin 7, connect +5 V to pin 14.

What this does is produce a complemented direction signal from
pin 6, and then AND the true and complemented direction signals
with the step pulse to produce step pulses going each way.

If your software produces negative-going step pulses, then you need
to use a 74LS02 instead.

Jon