Re: [CAD_CAM_EDM_DRO] First CNC project

In a message dated 6/5/2003 8:36:25 PM Central Standard Time,
Tomr@... writes:

> Question #1. How do I interface between a PC and the stepper drives?
> Question #2. Do I connect throught the parallel port? What limitations
> exist?
>

Tom:

Forgive, if over-simplified: Answer #2: Yes. Those outputs are "defined"
as TTL levels, but I have found on the three or four PC's to which I have
connected via the parallel port that they seem to be usually BUFFERED well, so can
put out perhaps 20 mA at 4.5 VDC ("TTL" would be microamps at 2.8 volts!).

Answer #1: If pulse-width is not a question, nothing more than a 74HC541
(8-bit noninverting buffer) would do fine. If you must have wider pulses out
than your software provides, and you don't want to fiddle with the software to
extend "Time ON" of the output pulses, you could insert 74HC4538 dual
monostables with RC selected for several microseconds, etc.

Either specifies a 25 mA output at, what, 4.5 VDC, min, so these can input to
the Gecko's opto-isolator [LED-] inputs just fine. BEEN there; DONE that.

Jan Rowland


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