Null modem

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A null modem is a device that allows one to connect two computers together, typically with only a serial port. No networking hardware such as a NIC or a modem are required for this.

Null modem cable

Also known as a RS-232 cable, a null modem cable is a specially designed cable that allows a user to connect two computers directly to each other via their communications ports (RS-232 ports). Null modems are particularly useful with portable computers because they enable the portable computer to exchange data with a larger system (i.e. a desktop computer or desknote).

Null modem cable pin mapping

This is the most common pin mapping, one common variant is to also connect pins 1 and 6

Here is another pin connection diagram for a null modem:

See also

• Client-Server.
• InterLnk
• USB.
• Wi-Fi.
• Network bridge.

External links

• http://ourworld.compuserve.com/homepages/harburg/Link2PCs.htm
• http://www.unh.edu/helpdesk/webdoc/14.227.html
• http://www.angelfire.com/ma/mantasdos/interlnk.html
• http://www.ms-dos.com/dos-i/intexe-i.htm
• http://www.daniel-hertrich.de/rs232/
• http://www.eastoverhill.com/techref/pinouts/ibm_pc.htm