Hi,
that is just another speed controller board....its not an encoder. Mach will have no idea how fast the spindle is going unless you have an
encoder or an index pulse.
A speed controller board will drive the spindle just fine but if Mach sends out a 50% duty cycle PWM you'd expect and want the spindle to do 50%
speed, and it may be close, but likely not better than 10%. Once the spindle comes under load it will slow down, and Mach has no way to know that
nor have any means to correct it.
Craig