| EIA-232 (Formerly "RS-232") The most common . EIA-232 is the equivalent of {V.24}, and {V.28}. EIA-232 specifies the and pin use of connectors, but not their physical type. specifies the electrical signals. 25-way connectors are common but often only three wires are connected - one ground (pin 7) and one for data in each direction. The other pins are primarily related to between sender and receiver and to on , inoperative circuits, busy conditions etc. The standard classifies equipment as either (DCE) or (DTE). DTE receives data on pin 3 and transmits on pin 2 (TD). A DCE EIA-232 interface has a female connector. DCE receives data from DTE on pin 2 (TD) and sends that data out the analog line. Data received from the analog line is sent by the DCE on pin 3(RD). Originally DCE was a modem and DTE was a computer or terminal. The terminal or computer was connected (via EIA-232) to two modems, which were connected via a telephone line. The above arrangement allows a computer or terminal to be connected to a modem with a straight-through (2-2, 3-3) cable. It is common, however, to find equipment with the wrong sex connector or with pins two and three reversed, requiring the insertion of a cable or adaptor wired as a or . Such an adaptor is also required when connecting a computer directly to a terminal or to another computer without the use of modems. (1999-12-28) |
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