Peter:
It would appear that I have not been clear on what I am doing. I am retro fittig an existing CNC router with a new control and am making the PLC (Programmable Logic Controller) using an 8052 circuit. The machine already has incremental encoders, feedback tachometers and servo drive power supplies and amplifiers for the DC servo motors.

What I am wanting to do is take the step and direction control pulses/signals that are being output from the parallel port on the PC (generated by the motion control software), input them into the 8052 and output from the 8052 a PWM signal or a digital signal which can be converted to an anolog voltage of +/-10 Vdc. If it is easier to output a PWM signal that is easily converted to my analog voltage via an op amp circuit.

There is already an incremental encoder on the DC motor as well as a feedback tachometer which sends a voltage signal back to the servo amplifier that I want to control.

Sorry for the incomplete information in the beginning.

Randy Abernathy