AT&T MERLIN LEGEND System Reference Manual page 532

Hardware
5-26 Adapters
The data module can be configured as a stand-alone by ordering a
WP90110,L1 power unit (PEC21625). The data module can also be configured
in a multiple-mount arrangement by ordering a Z77A data mounting (PEC
21626), which provides a common power supply for up to eight data modules.
Both the power unit and the data mounting require a 115-VAC power outlet.
Neither the power unit nor the data mounting is provided with the data module;
both must be ordered separately.
The ISDN 7500B Data Module does not have the internal 100-ohm line
termination that is provided with MLX telephones. Therefore, when it is used
without an MLX telephone, a 100-ohm 440A4 terminating resistor adapter (PEC
2709-A59) must be installed on the line near the data module.
To provide synchronous operation at speeds up to 64 kbps, the following
optional circuit boards must be ordered:
Multipurpose Enhancement Board. Provides an RS-366 Automatic Calling
Unit (ACU) interface and converts the RS-232 interface on the main circuit
board from asynchronous to synchronous. A V.35 adapter cable must be
ordered separately to operate at the lower data rates and also at data rates
of up to 56 and 64 kbps. Without the adapter cable, data rates are limited to
1200, 2400, 4800, 9600, and 19,200 bps.
High-Speed Synchronous Interface Enhancement Board. Provides a V.35
interface at synchronous data rates of 48, 56, or 64 kbps. A V.35 adapter
cable that converts the 25-pin male connector on the board to the industry-
standard 34-pin V.35 interface is included.
Data Module Features
The ISDN 7500B Data Module offers the following features:
Asynchronous Features
RS-232 interface
asynchronous full-duplex operation
selected data rates of 300, 1200; 2400, 4800, 9600, and 19,200 bps
data options set via the data terminal attached to the RS-232 interface
ability to change options without dropping a data call
autobaud (also called data metering or speed matching) — the ability to
adjust the speed of transmission to match the speed of the data terminal
being called
auto-adjust — the ability to adjust to the speed and parity of the data terminal
being used
call setup (dialing) from the keyboard of an ASCII data terminal by using the
local command (CMD) mode or AT mode
automatic or manual answering of incoming data calls