All I have to send as to be in hexadeciamel ?
Hexadecimal is a text representation of a number. So do you have to send text or do you have to send the numbers.
I have to send informations like a start data (0xAC) and informations like motor power (-1000/0/1000)...
Please fill in those dots at the end. With the information that you gave, you now probably have access to the datasheet/documentation for motor(driver). Post it here.