Solution:

In PC-ComLIB 6.0, users can use the function sio_baud (int port, long speed) to set a special baud rate directly. There is a prerequisite for this function: the baud rate base clock frequency of PCL-844H should be divisible by (baudrate*16). The base clock frequency of PCL-844H is 14745600 Hz. It is divisible by 3200, so you can set the baud rate to 200. The sio_baud function can also be used for PCL-844 and PCL-747.