Connect the encoder's output to the KANGAROO's input (use the channel 1). Make sure that is correctly connected (5v, ground, A, B) Some encoder's have the "I" wire. The ones I have don't. And it works perfectly.

   Connect the motor power (+ / -) wire to the A1 and B1 SABERTOOTH's terminals
   Power up the Sabertooth using the + and - terminals.

   ATTENTION! Be very careful doing that wiring! if you invert the poles you're gonna fry your board!