user manual

E-2
EIA-232-D Interconnections
E
Table E-1. EIA-232-D Interconnections
Pin
Number
Signal
Mnemonic
Signal Name and Description
1 CHASSIS GROUND. Not always used. See section Proper
Grounding.
2 TxD TRANSMIT DATA. Data to be transmitted; input to the modem
from the terminal.
3 RxD RECEIVE DATA. Data which is demodulated from the receive
line; output from the modem to the terminal.
4 RTS REQUEST TO SEND. Input to the modem from the terminal
when required to transmit a message. With RTS off, the modem
carrier remains off. When RTS is turned on, the modem
immediately turns on the carrier.
5 CTS CLEAR TO SEND. Output from the modem to the terminal to
indicate that message transmission can begin. When a modem is
used, CTS follows the off-to-on transition of RTS after a time
delay.
6 DSR DATA SET READY. Output from the modem to the terminal to
indicate that the modem is ready to transmit data.
7 SIG-GND SIGNAL GROUND. Common return line for all signals at the
modem interface.
8 DCD DATA CARRIER DETECT. Output from the modem to the
terminal to indicate that a valid carrier is being received.
9-14 Not used.
15 TxC TRANSMIT CLOCK (DCE). Output from the modem to the
terminal; clocks data from the terminal to the modem.
16 Not used.
17 RxC RECEIVE CLOCK. Output from the modem to the terminal;
clocks data from the modem to the terminal.
18, 19 Not used.
20 DTR DATA TERMINAL READY. Input to the modem from the
terminal; indicates that the terminal is ready to send or receive
data.
21 Not used.