A motor driving system includes a storage unit, a driver, and a controller. The driver includes a first programmable logic device (PLD). The controller includes a second PLD. The storage unit stores a control program. The controller generates a first transmission data to the first PLD and a second transmission data to the second PLD according to the control program. The first PLD generates a first message packet including the first transmission data. The second PLC generates a second message packet including the second transmission data. The first and second PLDs communicate with each other using a full duplex transmission mode or a half duplex transmission mode.