# Nullmodem (25-25)

Use this cable between two DTE devices (for instance two computers).

(To Computer 1).
(To Computer 2).

25 PIN D-SUB FEMALE to Computer 1.
25 PIN D-SUB FEMALE 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

Note: DSR & CD are jumpered to fool the programs to think that they are online.

Contributor: Joakim Ögren, Drew Sullivan, Niklas Edmundsson, Don Rifkin, Richard Marker

Source:
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Copyright © The Hardware Book Team 1996-2001.
May be copied and redistributed, partially or in whole, as appropriate.
Document last modified: 2001-06-08