Motorola MVME2603-1121A, Installation And Use Manual

Page: 181 / 210

Serial Interconnections
C-3
C
Table C-1. EIA-232-D Interconnect Signals
Pin
Number
Signal
Mnemonic
Signal Name and Description
1 Not used.
2 TxD Transmit Data . Data to be transmitted; input to modem from terminal.
3 RxD
Receive Data . Data which is demodulated from the receive line; output from
modem to terminal.
4 RTS
Request To Send . Input to modem from 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 modem to 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 modem to terminal to indicate that the modem is
ready to send or receive data.
7 SG Signal Ground . Common return line for all signals at the modem interface.
8 DCD
Data Carrier Detect . Output from modem to terminal to indicate that a valid
carrier is being received.
9-14 Not used.
15 TxC
Transmit Clock (DCE). Output from modem to terminal; clocks data from the
terminal to the modem.
16 Not used.
17 RxC
Receive Clock . Output from terminal to modem; clocks input data from the
terminal to the modem.
18, 19 Not used.
20 DTR
Data Terminal Ready . Input to modem from terminal; indicates that the terminal
is ready to send or receive data.
21 Not used.
22 RI
Ring Indicator . Output from modem to terminal; indicates that an incoming call
is present. The terminal causes the modem to answer the phone by carrying
DTR true while RI is active..
23 Not used.
24 TxC
Transmit Clock (DTE). Input to modem from terminal; same function as TxC on
pin 15.
25 BSY
Busy . Input to modem from terminal; a positive EIA signal applied to this pin
causes the modem to go off-hook and make the associated phone busy.