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

[Jordan K. Hubbard]

On Jan 18, 2012, at 1:10 AM, Dave Baldwin wrote:

> PC based CNC controllers are suck in the dark ages - not only for the GUI they present but in how they control the steppers via the printer port.  They rely on low level Window's drivers to generate accurate timing pulses (on the parallel port pins) and this process is easily disrupted by other system activity.  On a dedicated controller you can disable many of the system activities (network wifi, virus scanning, etc.) that will loose you accuracy, but even so the number of steps per second you can reliably generate is limited.

That's an excellent point, of course.  I might also offer, depending on how real-time the requirements of your CNC equipment is, an alternative solution which would be to pick up a programmable microcontroller (many fine ones exist these days, with both USB and parallel interfaces to boot) and off-load the responsibility for servicing the equipment to it, then talking high-level to the microcontroller over USB from your MacRuby app.  There are quite a few folks doing smaller-scale Arduino CNC jobs (just google for "arduino CNC" for a random sampling) and, depending on how industrial your needs are, the Arduinos are a dream to program for.

- Jordan

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