Serial (RS-232C/RS-422A) Interface (Option)
C-8
TXD – Transmit Data – (Pin 2)
This output carries asynchronous data sent by the printer to the computer. It is used mainly in
handshaking protocols.
RXD – Receive Data – (Pin 3)
This input carries serial asynchronous data sent by the computer to the printer.
RTS – Request To Send – (Pin 4)
This output is always held high (above 3 volts).
CTS – Clear To Send – (Pin 5)
DSR – Data Set Ready – (Pin 6)
Unused.
SG – Signal Ground – (Pin 7)
All signals can transmit between the printer and the host computer to send each signals with a signal
ground.
DTR – Data Terminal Ready – (Pin 20)
This output is used as a buffer nearly-full handshake line. It is held high (above 3 volts) when the
buffer can accept more data.
RS-232C Interface Voltage Levels
The voltage levels of the interface signals conform to EIA RS-232C specifications. SPACE is from 3
volts to 15 volts. MARK is from –3 volts to –15 volts. Voltages between –3 volts and 3 volts are
undefined.
