RS-232 SERIAL DB-25 to SERIAL PRINTER NULL MODEM CABLE (Universal) DB-9 Female PC DB-25 PIN Female PC DB-25 PIN Male printer 2 < RD --------- 3 <------------------------------------- 2 Transmitted data 3 > TD --------->2 -------------------------------------> 3 Receive data 5 < GND -------- 7 <------------------------------------> 7 Ground 8 < CTS -------- 5 ------------------------------------ 6 to 8 to 20 1 to 4 to 6 6 to 8 to 20 4 to 5 DTR/DSR/DCD DTR/DSR/DCD RTS to CTS Note!! Use this cable pinout for direct connection between a PC serial port and a serial printer. The 1/4/6 and 6/8/20 loopbacks are to enable the interface as if a modem was attached. SEIKO(SHA) SP-2400 Example DB-9 Female PC DB-25 PIN Female PC DB-25 PIN Male printer 2 < RD --------- 3 <------------------------------------- 2 Transmitted data 3 > TD --------->2 -------------------------------------> 3 Receive data 5 < GND -------- 7 <------------------------------------> 7 Ground 8 < CTS -------- 5 ------------------------------------ 20 DTR 1 to 4 to 6 6 to 8 to 20 (some machines would work DTR/DSR/DCD DTR/DSR/DCD without this "loopback")