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Appendix B Host Computer Interface
B-3
The pins of the printer’s RS-232C interface connector carry
the signals listed in the table below. 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 com-
puter 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.
A protocol is a set of rules the computer follows in sending
data to the printer. They are indicated on the status page. Pa-
rameters can be changed from the operator panel. See
Changing Serial Interface Modes on page 3-19
. The parame-
ters and their identification codes are given below.
H1: Baud rate
The factory default setting is 9600 baud.
H2: Data bits
7 or 8; the factory default setting is 8.
H3: Stop bits
1 or 2; the factory default setting is 1.
H4: Parity
The factory default setting is None (0 on the status printout).
3. Serial Interface (Option)
3.1 RS-232C Interface
Pin In/out Signal Description
1 - FG Frame ground
2 Out TXD Transmit Data
3InRXDReceive Data
4 Out RTS Request To Send
5InCTSClear To Send
6 In DSR Data Set Ready
7- SGSignal Ground
20 Out DTR Data Terminal Ready
Table B-3
4. RS-232C Protocol
Parameter value Baud rate
12 1200
24 2400
48 4800
96 9600
19 19200
38 38400
57 57600
11 115200
Table B-4
Parameter value Meaning
0 None
1Odd
2Even
3 Ignore
Table B-5