Data modules and asynchronous data units

Understanding RS-232 communications

To install a data module, you have to set up the device to work with RS-232 devices.

NOTE:

Data modules, PGATE boards, printers connected through data modules, SATs connected through data modules, and anything related to the X.25 connectivity protocol are not supported on the S8300 or S8700 Media Server platforms.

The RS-232 communications protocol defines a communications link as a Data Communications Equipment (DCE) device and a Data Terminal Equipment (DTE) device connected by an RS-232 cable. The send and receive pins on DCE equipment (pins 2 and 3) are reversed on DTE equipment, so that the DCE transmit pin connects to the receive pin of the DTE and vice versa.

Generally, the term DCE is applied to devices that mediate between customer equipment and the carrier or network. Such devices include modems, data modules, and data units. DTE describes devices that provide a user interface for data communications, such as dumb terminals and PCs. When configured as DTE, data modules are used for asynchronous modem pooling. When configured as DCE, data modules are analogous to modems in that they link a device such as a terminal or PC (DTE) to DEFINITY.

To install a data module correctly, you identify the connected equipment as DCE or DTE and do one of the following:

Configure the modem for a DTE or DCE connection

Install a null-modem converter

Detailed instructions are provided for each modem type, beginning on page 49.

48 Issue 4 October 2002

555-233-116

Page 48
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Avaya 555-233-116 manual Understanding RS-232 communications