Re: Serial port protocol

----- Original Message -----
From: Ron Ginger
To: CAD_CAM_EDM_DRO@onelist.com
Sent: Tuesday, February 01, 2000 9:51 AM
Subject: [CAD_CAM_EDM_DRO] Serial port protocol


From: Ron Ginger <ginger@...>

Since we want the real math to be in the PC, how about something very
close to Gcode, but in step counts, not inches. Actually that may be
about the same as HPGL.

Ron,

If I'm not mistaken, the LPT Indexer uses something like this to do it's
thing. I have played a little bit with generating this form of output,
using the scale function that is available in my favorite Cad-Cam systems.
LPT does have a direct HPGL driver too. Bobcad used to sell a program
called the FN controller that could generate this kind of code from standard
G-code. It was a live front end for the LPT indexer, something like Hoyt's
program.

I believe the Galil driver boards use a similar pulse or step count for
their proprietary instructions. You might look at either of these systems
for ideas as to what a low-level (Lower than G-code) programming language
could look like.

Whatever you do, try to avoid the representation of arcs with beginning and
ending angles. This form of arc representation is popular with some of
these systems, and cannot be easily configured from a Cad-Cam system. I
have found in some cases that this form was programmed by motion control
engineers that were too SMART to learn G-code, and hence they developed
proprietary and stand alone systems. I have used linear interpolation in
Cad-Cam in some cases to support direct programming of arcs to get around
the bastardized definitions of arcs.

I mention the LPT Indexer and Galil because they are very common commercial
systems.