Help with Analog to digital conversor signal

Hi everyone, I have a problem with a Prolight turning center it was working until last week.

Z axis is not working anymore, si I try to put a new driver and a stepper motor but the computer send Analog signal to control the old driver and the newone's are digital controlled

I take readings and the board send from 0 to 0.5 volts for turn de motor, so the question is.

Any body solve this kind of trouble before?

I serch like crazy to find a solution. I read somting about (ADC) but not find a specific module to convert the analogic to Pwm.

I realy want to fix this problem ading a now digital driver input to control a stepper motor with the old software hardware

Please gime some advice.

Thanks