Select High Speed or Normal Speed Mode

  The JP1 is used to select high speed mode or normal speed mode of port 1 and the JP2 is used to select high speed mode or normal speed mode of port 2; the clock is 7.3728MHZ for high speed mode, and 1.8432MHZ for normal speed mode. For high speed mode, the baud rate speed up to 460K. 

The JP3 & JP4 are select RS232/422/485 Mode.