problem on Scorpion XL 2.0 Motor Driver

Hello, I am using the Scorpion motor driver ( and intended to use it to control the speed of a motor (want to lower down the motor speed). My idea is to use an Arduino to connect to the motor driver, which is connected to the motor. Also, the power (12VDC) is connected to the motor driver. I think my wiring is no problem. My problem is that the motor driver did not reduce the speed. I mean the motor spiun but the speed was not reduced. Can someone help a little bit?

The Arduino code is here:

const int spinSpeed = 77;

void setup() {

// put your setup code here, to run once:




void loop() {

// put your main code here, to run repeatedly:

pinWheel.write(77); // write this value to control motor speed via motor driver







Thanks very much.

Already solved. Thanks