[MacRuby-devel] CNC Machine control using USB to IEEE 1284 Parallel port adapter

[Robert Rice]

Hi Will,

Thanks for the info on Arduino - looks like some interesting possibilities there. I didn't realize that Arduino had several different boards available. I may be able to connect one or more boards to a DB25 parallel connector to control my HobbyCNC micro-stepping driver board.

Thanks,
Bob Rice

On Jan 18, 2012, at 10:33 AM, Will Thorne wrote:

> 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-request at 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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