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B.2
Serial Interface
B.2.1
Interface Signals
B.2.2
Interface voltage levels
B.2.3
Serial connector
Table B-2
below shows the pins and corresponding input and output signals of the RS-232C
interface connector.
Pin
In or out
1
—
FG
2
Out
TXD
3
In
RXD
4
Out
RTS
5
In
CTS
6
In
DSR
7
—
SG
20
Out
DTR
Table B-2
The voltage levels of the interface signals conform to EIA RS-232C specifications. The
voltage level of SPACE is 3 to 15 volts. The voltage level of MARK is -3 to -15 volts. Voltages
between -3 and 3 volts are undefined.
The serial interface connector (RS-232C) is a DB-25S connector. Use a cable with a DB-25P
connector or its equivalent for this connector.
Signal
This pin is connected directly to the
Frame Ground.
printer frame.
This pin is used to output asynchronous
Transmit Data.
data sent from the printer to the computer. This signal is
often used in handshaking.
This pin is used to input serial asynchro-
Receive Data.
nous data sent from the computer to the printer.
Request To Send.
volts).
Clear To Send. Not used.
Data Set Ready. Not used.
This pin is used to establish a common ref-
Signal Ground.
erence level for the voltages of all signals other than
Frame Ground.
Data Terminal Ready .
of the printer buffer (i.e., nearly full or nearly empty)
when handshaking is used. The pin goes high (above 3
volts) when the buffer is able to accept more data.
B-5
Description
This output is always high (above 3
This pin is used to notify the status
Interface Signals
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