Appendix C Host Computer Interface
C-3
Installing the optional serial interface board kit (IB-
11) in the printer enables connection to a computer
with an RS-232C standard serial interface.
Interface Signals
The pins of the printer’s RS-232C interface connector carry
the signals listed in table below. The table also indicates
whether each signal is incoming or outgoing with respect to
the printer.
Serial Connector Pin Assignment
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 signal 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.
Serial Interface (Option)
RS-232C Interface
Pin
In/out
Signal
Description
1
-
FG
Frame Ground
2
Out
TXD
Transmit Data
3
In
RXD
Receive Data
4
Out
RTS
Request To Send
5
In
CTS
Clear To Send
6
In
DSR
Data Set Ready
7
-
SG
Signal Ground
20
Out
DTR
Data Terminal Ready
