RS-232 Serial Interface Interface board specifications (RS-232-compliant) Functions of each connector pin 138 Item Specifications Data transfer method Serial Synchronization Asynchronous Handshake Select one of the following with DIP switch 1-3: • DTR/DSR • XON/XOFF Signal level MARK SPACE -3V to -15V logic “1”/OFF +3V to +15V logic “0”/ON Bit length Select one of the following with DIP switch 1-4: • 7 bit • 8 bit Transmission speed [bps: bits per second] • Select one of the following with DIP switch 1-7/1-8: 4800/9600/19200/38400 bps • Select one of the following with commands: 2400/4800/9600/19200/38400/57600/115200 bps Parity check Select one of the following with DIP switch 1-5:
• Yes • No Parity selection Select one of the following with DIP switch 1-6: • Even • Odd Stop bit 1 or more bits However, the stop bit for data transfer from the printer is fixed to 1 bit. Connector Printer side DSUB 25-pin (female) connector Pin no. Signal name Signal direction Function 1 FG — Frame ground 2 TXD Output Transmission data 3 RXD Input Reception data 4 RTS Output Equivalent to DTR signal (pin 20)