.05 vdc unchanged at parallel port?

[FLUTE HEAD]

Well I may have discovered why no motion for my set-up. I measured the voltage at pins 3 and 18 ground for parallel port. The result is .05 vdc unchanged when I try to jog in turbo cnc. Is there something I can do to get this voltage up to specs for xylotex? Voltage needs to be .7 * 5vcc which = 3.5 vdc at p-port. Maybe a setting? Last known the printer worked fine. Should I change something out in my computer to get the voltage I need? thanks,

matt

[arvidb]

Did you measure with anything attached to the port? In that case you might have a short-circuit to ground on that pin (#3). Otherwise it sounds like some setting in your control program needs to be changed.

Arvid

[jfong]

Some suggestions....

Pin 18 *may* not be ground on your parallel port, it is suppose to be. Try using pin 25 as your ground.

Also your volt meter may not be able to register much of a change in voltage if a high enough pulse rate is being sent out of pin 3. The step pulse is narrow, only a few microseconds. I use a oscilliscope instead of a voltmeter to check my parallel port. Try changing the turbocnc setting to active low instead of active high for pin3. This will make the output of the parallel port "high" when not sending any pulses. If you read 3volts or more with your voltmeter, the port is probably good.

Jim

[FLUTE HEAD]

Thanks everyone, the reason no change in voltage was because when I was measuring the voltage I was jogging in the wrong direction. Jogging positive no change, jogging negative 4.9 volts change. So now I still don't know why my machine will not turn stepper motors. I guess I'll try to lower the stepp resolution from 1/8 stepp mode.