Motorola MVME712B 用户手册

Interconnect Signals

3-19

A23

46

RXD4

RECEIVE DATA (serial port 4) - data that is 
demodulated from the receive line is presented to the 
terminal by the modem. 

C24

47

GND

GROUND 

A24

48

RTS4

REQUEST TO SEND (serial port 4) - RTS is supplied 
by the terminal to the modem when it is 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. 

C25

49

GND

GROUND 

A25

50

Not used. 

C26

51

DTR4

DATA TERMINAL READY (serial port 4) - a signal 
from the terminal to the modem indicating that the 
terminal is ready to send or receive data. 

A26

52

CTS4

CLEAR TO SEND (serial port 4) - CTS is a function 
supplied to the terminal by the modem, and 
indicates that it is permissible to begin transmission 
of a message. When using a modem, CTS follows the 
off-to-on transition of RTS after a time delay. 

C27

53

GND

GROUND 

A27

54

DCD4

DATA CARRIER DETECT (serial port 4) - sent by the 
modem to the terminal to indicate that a valid carrier 
is being received. 

C28

55

GND

GROUND 

A28

56

Not used. 

C29

57

GND

GROUND 

A29

58

TXD2

TRANSMIT DATA (serial port 2) - data to be 
transmitted is furnished on this line to the modem 
from the terminal. 

C30

59

GND

GROUND 

A30

60

RXD2

RECEIVE DATA (serial port 2) - data that is 
demodulated from the receive line is presented to the 
terminal by the modem.