For the SportDevices PWS you should use Analog. You need to swap the jumpers inside the box. 

@admin
Why analog rather than PWM ?

With analog the settings are simpler, just min and max voltage (0 and 5V). But with proper settings (max duty cycle and frequency) PWM works just as good as far as I know.

Just looked and i dont have an analog input, its optional. How should i figure out duty cycle and frequency?

Signal period 416 ms, am i right? 
Maximum pulse width is now 60% and minimum 0%.
Will raise from 60% if i need more braking power, is the maximum 100% safe or should i use ~90% if needed rather than 100%?

PWS3.2b
 Modulation Method: Phase Angle Control (SCRs) @ 100 Hz
 Inductive Load Control: Flywheel diode (passive discharge) 

Control lines:
 PWM input: PWM 0 to 5 Volt, 2.4 Khz. ISOLATED:
o + Brake output (SP4/SP5)
o - GND

Correct, 2.4Khz is 416 micro second. 

I don't know SportDevices max duty cycle. It may be 100%, I would try that.