P C / 1 0 4 C P U M o d u l eP F M - 5 4 0 IR e v . BChapter 2 Quick Installation Guide2 - 102.7 CFD Master/Slave Selection (JP1)JP1Function1-2Slave2-3Master (Default)2.8 RS-232 Ring/5V Selection (JP2)JP2FunctionCOM11-3+5V3-5Ring (Default)COM22-4+5V4-6Ring (Default)2.9 LCD Clock Selection and Clear CMOS (JP3)JP3FunctionLCD Clock1-3Normal (Default)3-5ReverseCMOS2-4Protected (Default)4-6Clear