I've been working on fixing up an old Bridgeport Boss w/ CNC retrofit, and in the process changing from TurboCNC to Mach3. We're very close, on an oscilloscope we have Mach3 giving 0.6v Lo Dir signals, and 3.4v Hi Dir signals. For Step we get 3.4v with a 5us pulse downwards, which is what we need for our Larken Cobra Stepper Drivers.
The issue I'm trying to figure out is why we are getting 3.4v Hi signal outputs and not 5v signal outputs. We are using the A25 from CNC4pc, a 5v PCI-Parallel Port card, on a 32-bit 5v PCI rail. We get a 5 volt signal from all of our Status/Control pins on the parallel port, but 3.4v on all of the Data pins. Is this something caused by Mach3 as it controls the outputs of the Data pins? ATM our motor does not step, but makes a slight humming noise constantly, I believe the stepper drivers expect a 5v Step signal.