we have have a biesse 325 rover with a cni rt480 control
it uses soprel servo drives i think rs485 communication
can mach 3  control it fully or inpart

Hi, Sidskilly

For the most part Mach uses Step/Direction commands.

Check your servo control boards inputs, If its analog +-10 volts theres a few interface boards to convert them to step/direction.

Just a start Hear, Chip

I have Googled these machines  - but only come up with limited data - and no explanation of what drives the thing.

Mach 3 can cantrol anything with up to 6 axis - but the problem is matching the output from the computer to your machine.

As Chip says, Mach 3 is simple. It puts out step pulses to drive the axis motors - (step is a controlled unit, frequency = speed, number of pulses = distance) and it puts out direction pulses. So with three wires ( step, dir and return) you can control the axis.
The drive spindles can be controlled by Pulse Wave Modulation, or Step and Direction pulses.

The problem is, what does the Biesse require by the way of signals. Most of the 325 advertised were 1992 vintage with their own control and GCode system, but no indication of how this worked.

You can change the drive motors for more modern steppers or servos with the relevant drivers, but this could negate the cheap price of the machine by the time you have converted it.

I think you need to do a little more research to find what makes these machines tick - unless anybody on the forum has any knowledge