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C.2. RS-232C/RS-422A Interface
C-5
C.2. RS-232C/RS-422A Interface
RS-232C interface
Interface Signals
The pins of the printer's RS-232C interface connector carry the signals listed in Table C.2. The table
also indicates whether each signal is incoming or outgoing with respect to the printer.
Brief descriptions of the signals follow.
FG - Frame Ground - (Pin 1)
This pin is connected directly to the printer frame.
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.
Table C.2. RS-232C Signal Pin Assignments
Pin In/out Signal Description
1-FG
Frame ground
2OutTXD
Transmit Data
3InRXD
Receive Data
4OutRTS
Request To Send
5InCTS
Clear To Send
6InDSR
Data Set Ready
7-SG
Signal Ground
20 Out DTR
Data Terminal Ready