I got a mid size mill a with controller (professionally built) but still struggling to get any connectivity PC-to-Controller. Standard parallel connection, straight through cable. Tried 4 different computers with onboard parallel ports and 2 plug in PCI parallel cards no luck. So decided to test parallel port pins on the computer side with an occilloscope.

Launch Mach 3, scope charge pump pin (pin 9 in my case) = 6.8Khz !?!?! Close Mach3, reopen charge pump = 11.83Khz !?!? Sometimes it comes to 12.2Khz but never 12.5Khz claimed by Mach manual. My pulse freq reported by Mach in diagnostics is about 23656 to 24500 Hz.

I tried to output a frequency on stepper X (pin 7 in my case) and it comes out properly each time and is inline with Mach freq. So when I dial 25000Hz on stepper X it shows exactly Mach 3 pulsing frequency, say 23656 Hz.

But I am a little confused on the charge pump as it obviously way out of range. Does that mean my parallel port is no good? What is charge pump used for anyway? Can I disable it at all? How else can I ensure that the parallel port has suitable characteristics? How can I debug the problem?

I tried 3 different computers and on board parallel ports and they all output charge pump at 6.8Khz (sometimes jumping to 11.8Khz).

Any ideas?

The Charge pump is primarily used to stop any motor movement whilst the computer is booting. It has been seen as a safety feature whilst running Mach but is not meant as such. I dont use the chargepump on my machines, but you may need to if your computer manically polls the parallel port on boot up.

Hood

What are the specs of the computers you have tried? Did you do a fresh install of Windows on the computers and run through the Mach optimization steps? Then run the driver test as mentioned above.

I like to recommend the SmoothStepper to folks: http://soigeneris.com/Warp9.aspx, it takes care of all the timing critical pulse generation for Mach freeing up PC resources.