Avaya 3910 Guía De Conexión

Serial ports (also sometimes referred to as communications ports or COM
ports) are hardware interfaces which permit your PC’s microprocessor to
communicate with peripheral devices using a communications standard called

RS-232 (hence, serial ports are also sometimes referred to as RS-232 ports).
Many common computer accessories make use of serial ports, including serial
mice, modems, serial printers, and the PassageWay adapter.

Under DOS (and Windows, which works cooperatively with DOS), the serial

port interfaces in a PC are uniquely identified by specific device names:
COM1 ("serial communications port 1"), COM2 ("serial communications port

2"), and so on, usually up through COM4. A particular PC might have none of

these devices, some of them, or all of them installed. For example, most PCs

currently on the market arrive from the manufacturer with two serial ports
already installed (COM1 and COM2), often integrated onto the computer's

main system board. Installing additional serial ports (for example, COM3 or

COM4) is usually accomplished by purchasing an add-on card and installing it

into a free expansion slot.

For most purposes (for example, configuring software), the generic description

of serial ports provided by their device names is sufficient. For example,

during the PassageWay Solution installation procedure, you are asked to

provide the device name of the serial port to which you have connected the

PassageWay adapter (for example, COM2). Unfortunately, this abstract view

of serial ports is not sufficient for other purposes, notably for troubleshooting
problems: to be able to do this effectively, a basic understanding of serial port
hardware is required. In particular, it’s essential to understand the mechanics
by which the computer’s microprocessor communicates with serial port
hardware.

The microprocessor/seriai port communication consists of two aspects: an I/O
port address and an interrupt request signal (IRQ). The I/O port address