Null modem is a communication method to directly connect two DTEs (computer, terminal, printer, etc.) using an RS-232 serial cable.

Apr 4, 2019 · Null modem, also called crossover, is a term associated with serial (RS-232) cables. A standard serial cable, also called an AT cable, has the wires inside the cable running straight through. Take a DB9 cable as an example. Pin 1 on one end of the cable would be connected to Pin 1 on the other end. Then Pin 2 to 2, 3 to 3, and so on.

Select the right RS232 null modem cable. In depth tutorial of all types of serial null modem cables. Includes easy to use selection table.

Nov 25, 2019 · Null modems allow creation of a connection between two computers that don’t have modems by way of their RS232 protocol. The RS232 protocol was originally used to connect a telephone modern to a teletype machine. The teletypes communicated to …

A Null Modem or "crossover" cable is used to connect to DTE devices together. For this to work, the Transmit (TxD) pin of one device needs to be connected to the Receive (RxD) pin of the other device, and vice versa.

Aug 23, 2024 · DB9 serial cables are most useful when connecting two devices that transmit data directly, for instance, between a computer and a modem. On the other hand, null modem cables are used when two similar devices, for instance, two computers, require a connection devoid of a …

What is a null modem cable? The difference between a modem cable and a null modem cable is easy to understand: A modem cable usually connects a computer to a modem. A null modem cable, on the other hand, connects two computers to each other, or a computer to a printer, point-of-sale system, etc.

A null modem serial cable (frequently called a crossover cable) is used to connect two DTE devices together without the use of a DCE device in between. For this to happen, the Transmit (TXD) and Receive (RXD) pins on one of the serial connectors are flipped.

Jul 11, 2008 · The purpose of a null-modem cable is to permit two RS-232 "DTE" devices to communicate with each other without modems or other communication devices (i.e., "DCE"s) between them. To achieve this, the most obvious connection is that the TD signal of one device must be connected to the RD input of the other device (and vice versa).

Mar 17, 2010 · Connector pinout and cable reference - 10Base-T crossover, serial, parallel, USB, VGA, audio, more!