Nullmodem

 

 

Nullmodem (9-9) Cable
(To Computer 1).
(To Computer 2).

 

  D-Sub 1 D-Sub 2  
Receive Data 2 3

Transmit Data

Transmit Data 3 2

Receive Data

Data Terminal Ready 4 6+1

Data Set Ready + Carrier Detect

System Ground 5 5

System Ground

Data Set Ready + Carrier Detect 6+1 4

Data Terminal Ready

Request to Send 7 8

Clear to Send

Clear to Send 8 7

Request to Send

 

Nullmodem (9-25) Cable
(To Computer 1).
(To Computer 2).

 

  D-Sub 9 D-Sub 25  
Receive Data 2 2

Transmit Data

Transmit Data 3 3

Receive Data

Data Terminal Ready 4 6+8

Data Set Ready + Carrier Detect

System Ground 5 7

System Ground

Data Set Ready + Carrier Detect 6+1 20

Data Terminal Ready

Request to Send 7 5

Clear to Send

Clear to Send 8 4

Request to Send

 

Nullmodem (25-25) Cable
(To Computer 1).
(To Computer 2).

 

  D-Sub 1 D-Sub 2  
Receive Data 3 2

Transmit Data

Transmit Data 2 3

Receive Data

Data Terminal Ready 20 6+8

Data Set Ready + Carrier Detect

System Ground 7 7

System Ground

Data Set Ready + Carrier Detect 6+8 20

Data Terminal Ready

Request to Send 4 5

Clear to Send

Clear to Send 5 4

Request to Send

 

Nullmodem (25-25) Adapter
(To Computer 1).
(To Computer 2).

 

  Female Male  
Shield Ground 1 1 Shield Ground
Transmit Data 2 3 Receive Data
Receive Data 3 2 Transmit Data
Request to Send 4 5 Clear to Send
Clear to Send 5 4 Request to Send
Data Set Ready 6 20 Data Terminal Ready
Data Terminal Ready 20 6 Data Set Ready
Ground 7 7 Ground