Solution:

The baudrate was fixed at 57600 with ADAM-5510 Utility. However, if you want to control this port under your application program, then we can control the CPU's Register directly to achieve you goal. But this method is more complex for our customer, following information just for your reference. FF80H : Serial Port Control FF82H : Serial Port Status FF84H : Serial Port Transmit Data FF86H : Serial Port Receive Data FF88H : Serial Port Baudrate Divisor