PPMC, etc.

[dave engvall <dengvall-at-elltel.net>]

Hi all,
After a month plus of frustration I have a ppmc
interface up and running on a real machine.

First of all let me talk about the machine, then
I'll go on to comments about the interface, etc.

Machine: Cincinnati 'contourmaster' tracer with
all the tracer stuff removed. Ballscrews on x and
y and for the purposes of this discussion z is
really w driven by an acme thread (knee).
Servo motors are an SEM  MT30H4  4:1 belt drive on
x, Pearless (about like the MT30 ) on y and a
small gearhead on w. Acu-rite 0.0002" glass scales
are used on all axis.
Servo drives are Servo Dynamics 1525-BR on x and y
and a GE HiAK (1980 vintage) drive is used on w.

Processor is a P200 ( from Boeing), interface is a
ppmc motherboard, encoder board and dac board from
Jon Elson/Matt Shaver. When received the boards
refused to work with my machine (Dell) or with a
P166 board I bought locally (cheap). I sent the
cards to Matt Shaver where they worked just fine.
To make a long story short the parallel interface
is critical. Matt shipped me a $20 IEEE-1284
compatible ISA parallel port which works just fine
in the P200 machine. At  first the ppmc was not
initializing correctly and Jon e-mailed me a
patched ppmc_encoder.c which I copied into the
source tree and recompiled. This patch provided
for more wait time upon initialization and fixed
the problem.  I'm running RH 5.2, 09J patch and
Mar 2000 emc code and xemc.

Paul has included the initial ppmc code in the
BDI. Jon's mod to ppmc_encoder.c was too late to
make it but should be easy to incorporate after
the initial install.  Paul, of course, had nothing
to test against so maybe at NAMES all the correct
resources will converge. :-)

Recommendations:

1. if you have problems with ppmc board set being
recognized: (a). try a different parallel board.
The one Matt sent me is: SIIG, Inc. Mod IO1818.

2. make certain you parallel port cable is
IEEE-1284 qualified. Keep it as short as
possible.  I'm using a 6'.
BTW  it takes a 25 pin to 25 pin not 25 pin to
Centronics.

3. Strain relief is nice on all cables into the
ppmc.

4. You probably want some kind of a card cage. I
made my own from aluminum stock and delrin (for
the card guides).  Some day we will get a pic up
on a web site but both Matt and I have the pics.

5. get the modified ppmc_encoder.c from Jon, Matt
or me and install it.

My thanks to Jon, Matt, etc. for taking on the
project of providing an alternative to the stg
card.

Dave