Hello,

Long time lurker making first post here. You could use an Arduino and do the 
real time pulse generation stuff on that. Then just write a macruby app that 
serialises the commands and feeds them to the Arduino which interprets them and 
flips the necessary IO pins on and off. It's years since I looked at this stuff 
but I seem to remember that CNC commands work such that they could be grouped 
into a single machining operation. Hypothetical example to cut a slot on a 
horizontal miller: Start milling cutter, start carriage +z, stop carriage, 
start carriage +x, stop carriage, start carriage -z, stop carriage, stop 
cutter. You could load that whole sequence into the Arduino if you break it 
down into groups like this. Put the arduino in a plastic box with a parallel 
port on one end and usb cable coming out the other? I don't know for sure that 
this would work, but in my experience microcontrollers are much simpler to do 
real time stuff on because they have pretty much no software stack compared to 
a desktop PC.

Will

On 18 Jan 2012, at 09:10, macruby-devel-requ...@lists.macosforge.org wrote:

> Hi,
> 
> I've become interested in Computer Numeric Control (CNC) machine control. I 
> find there is very little support for the Macintosh platform and many PC 
> programs for the task have a crude user interface so I would like to create a 
> Macintosh CNC application using MacRuby.
> 
> CNC programs and motor drivers generally use the LPT parallel port output 
> from a PC in the basic unidirectional mode. Most PC CNC apps do not support 
> PC laptops due to processor sleep logic interfering with stepper motor 
> timing. I would need a similar fast interface on the Mac.
> 
> I have a Prolific 2305 based USB to IEEE 1284 adapter cable that I would like 
> to use. Mac OS recognizes the device as an "IEEE-1284 Controller" in the USB 
> device tree and I can add a generic print queue for the device, but I don't 
> know how to connect to the device at high speed as the printer controller 
> does.
> 
> Prolific provides documentation for the simple report protocol for the 
> device. I suspect that an appropriate driver already exists for this device 
> but how would I find it?
> 
> Thanks,
> Bob Rice


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