Duet wifi Spindle - Mach 3 Speed Controler

[J.Helps]

Hi guys,

I'm building a CNC machine with a 400W Spindle (48V) that comes with a Mach 3 DC Speed controler that receives a pwm signal with a level of 3.5 - 12 V VPP. How can I setup this spindle with this controller?
I was thinking about using a pwm fan output from Duet but the output is 0-5V. Since I'm using a 24V power supply for the duet, can i use the fan output as VIN and add a step-down (24V to 12V) to connect to the spindle?

Mach3 DC motor speed controller datasheet:
https://www.mantech.co.za/Datasheets/Products/HQ-LB60-12A-V1-180191_SGT.pdf

[dc42]

@j-helps unfortunately the datasheet doesn't say whether the PWM input is isolated from the rest of the circuit. Please provide high resolution photos of both sides of the board, and report any markings you can read on component U5 next to the PWM connector.

[J.Helps]

@dc42