NULL MODEM CABLE PINOUT DB9 DB25
Serial (RS232) null modem cable (DB9-DB25). Pinout and
Serial (RS232) null modem cable (DB9-DB25). Pinout and signals for building a serial (RS232) nullmodem cable. Use this cable between two DTE devices (for instance two computers).
Null modem - Wikipedia
OverviewOriginsCables and adaptersApplicationsTypes of null modemNull modem is a communication method to directly connect two DTEs using an RS-232 serial cable. The name stems from the historical use of RS-232 cables to connect two teleprinter devices or two modems in order to communicate with one another; null modem communication refers to using a crossed-over RS-232 cable to connect the teleprinters directly to one another without the modems. It is also used to serially connect a computer to a printer, since both are DTE, and is known as a Printer Cable. ThSee more on enpedia · Text under CC-BY-SA license
RS232 serial cable pinout information - Lammert Bies
RS232 null modem cables. The easiest way to connect two PC’s is using an RS232 null modem cable. The only problem is the large variety of RS232 null modem cables available. For simple connections, a three line RS232 cable connecting the signal ground and receive and transmit lines is sufficient.