Controlling Reversible motor controller 24Vdc 15A with an Arduino and Maxuino

Hi there,
I am trying to control 4 DC motors (14.4 volt, about 10amp at peak) through 4 Reversible motor controller 24Vdc 15A like this one http://uk.rs-online.com/web/p/dc-motor-controllers/3639601/.

The Arduino will be controlled through Max/MSP’s Maxuino, there I will be able to control every digital pin and set them on High or Low etc.

The way I was going to do this is by wiring Arduino to the Ffwd Rev and H, S, L to control the speed.
So far I have had experience in wiring normal small DC motors controlled via Arduino or Hbridge and I haven’t seen the Ffwd and Rev controls, I was thinking about supplying PWM values through Max and in so control the speed, I am guessing the HSL is confusing me a bit.

Could anyone recommend how should I wire the Arduino to a single controller?
This would surely put me in the right direction in order to learn how to control the others.
Please let me know if you need more details or info, I am attaching one image of the controller, obviously I don’t want to blow anything up and will keep the power of the Arduino separated from that of the the Motor and external Power Supplier.
Should I ground the Arduino too?
Many thanks in advance.

Best wishes

Elso

I would first try and see what voltages are present on the control potentiometer in normal operation - so connect a 4k7 pot up and measure all three of its pins w.r.t. ground as you vary it and H and L presets.

It may be that the ends of the pot have a fixed voltage, or they may be determined by the presets.

Check what happens if each connection to the pot is broken - some controllers will detect such a fault and shutdown, others might not and can runaway at full speed it the low-side is broken. Controllers that detect a fault could need a 4k7 resistor in place of the pot should you try driving the wiper connection directly.

If the voltages are out of the 0..5V range obviously its not going to be easy.

If they are you might be able to low-pass-filter a PWM output to override the wiper connection (perhaps retaining a 4k7 resistor as well).