Serial Pinouts (D25 and D9 Connectors)
 


 

 

D-Type-25 Pin No.

D-Type-9 Pin No.

Abbreviation

Full Name

Pin 2

Pin 3

TD

Transmit Data

Pin 3

Pin 2

RD

Receive Data

Pin 4

Pin 7

RTS

Request To Send

Pin 5

Pin 8

CTS

Clear To Send

Pin 6

Pin 6

DSR

Data Set Ready

Pin 7

Pin 5

SG

Signal Ground

Pin 8

Pin 1

CD

Carrier Detect

Pin 20

Pin 4

DTR

Data Terminal Ready

Pin 22

Pin 9

RI

Ring Indicator

Table 1 : D Type 9 Pin and D Type 25 Pin Connectors

 

Pin Functions
 


 

 

  Abbreviation Full Name Function
     TD Transmit Data Serial Data Output (TXD)
     RD Receive Data Serial Data Input (RXD)
     CTS Clear to Send This line indicates that the Modem is ready to exchange data.
     DCD Data Carrier Detect When the modem detects a "Carrier" from the modem at the other end of the phone line, this Line becomes active.
     DSR Data Set Ready This tells the UART that the modem is ready to establish a link.
     DTR Data Terminal Ready This is the opposite to DSR. This tells the Modem that the UART is ready to link.
     RTS Request To Send This line informs the Modem that the UART is ready to exchange data.
     RI Ring Indicator Goes active when modem detects a ringing signal from the PSTN.