How Do You Build A Null Modem Cable?
A null modem cable is used to connect two computers together to allow them to communicate using a serial port. Each computer, however, is set up to send and receive information on exactly the same pin in the serial port. If a standard serial cable were used to connect the two machines, the information would collide in each port. A null modem cable reverses those ports so each computer can send and receive on the same ports. There are a number of different ways to configure null modems, including using a 9- or 25-pin serial cable. Open up the DB9 connectors with the small screwdriver to expose all the ports and connections for the wires. Strip both ends of three wires with the wire strippers. Expose just enough wire to fit in the DB9 connectors. Connect one end of the first wire to port number 2 on the first DB9 connector, and connect the other end to port number 3 on the second DB9 connector. Depending on the type of DB9 connector you have, this connection may be completed with a screw
