For connecting a printer/PC with a 25-pin RS-232C connector
PBX (9-pin) Printer/PC (25-pin)
Circuit Type
(EIA)
Signal
Name
Pin No.
Signal
Name
Circuit Type
(EIA)
BB RD (RXD) 2
BA SD (TXD) 3
CD ER (DTR) 4
AB
SG 5
CC
DR (DSR) 6
CA RS (RTS) 7
CB
CS (CTS) 8
1FG AA
3 RD (RXD) BB
2 SD (TXD) BA
20
ER (DTR) CD
7
SG AB
5 CS (CTS) CB
6
DR (DSR) CC
CF
4 RS (RTS)
Pin No.
RS-232C Signals
• Receive Data (RXD):…(input)
Conveys signals from the printer or the PC.
• Transmit Data (TXD):…(output)
Conveys signals from the unit to the printer or the PC. A "Mark" condition is held unless data or BREAK
signals are being transmitted.
• Data Terminal Ready (DTR):…(output)
This
signal line
is turned ON by the unit to indicate that it is ON LINE. Circuit ER (DTR) ON does not indicate
that communication has been established with the printer or the PC. It is switched OFF when the unit is
OFF LINE.
• Signal Ground (SG)
Connects to the DC ground of the unit for all interface signals.
• Data Set Ready (DSR):…(input)
An ON condition of circuit DR (DSR) indicates the printer or the PC is ready. Circuit DR (DSR) ON does
not indicate that communication has been established with the printer or the PC.
• Request To Send (RTS):…(output)
This lead is held ON whenever DR (DSR) is ON.
• Clear To Send (CTS):…(input)
An ON condition of circuit CS (CTS) indicates that the printer or the PC is ready to receive data from the
unit. The unit does not attempt to transfer data or receive data when circuit CS (CTS) is OFF.
• Frame Ground (FG)
Connects to the unit frame and the earth ground conductor of the AC power cord.
Installation Manual 243
2.12.1 Connection of Peripherals
