Motorola MVME187 User Manual

E-2

EIA-232-D Interconnections

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.