AT&T AT&T manual Asynchronous Data Units AD US

Asynchronous Data Units (AD US)

Asynchronous Data Units, and Multiple Asynchronous Data Units (MADUs), provide an interface between ports on the TN726 Data Line CP and RS-232C Data Terminal Equipment (DTE) or Data Communications Equipment (DCE). The DTE is equipment that provides a data source, termination, or both—a host computer, printer, or a data terminal are examples of DTE. The DCE is equipment that provides the functions required to establish, maintain, and terminate data communications—modems are the most common DCE.

The Z3A series of Asynchronous Data Units (ADUs) (Figure 4-17)are DCE that allow a direct connection between DTE and port circuits on the Data Line CP (TN726). To connect an ADU to DCE equipment, a cross-over cable (“null modem”) is required.

The modular jack labeled “Wall” connects the ADU to the building wiring with a standard 4-pair modular cord. The 400B2 Adapter is required to provide supplemental AC power and can be bridged at the wall jack if required (Z3A1, 2, and 4 units only).

The modular jack labeled “Telephone” allows a voice terminal to be attached to the ADU. Separate wire pairs from the telephone to the system cabinets are provided in a single 4-pair cable run back to the SIP. The pairs separate at the SIP for connection to voice and data ports.

The Z3A series of ADUs measure about 4.5 inches in length, 2 inches wide, and 1 inch high. The ADUs available are shown in Table 4-F.

The Z3A ADUs should be installed only on lightning-protected facilities; they are not designed to be used with CO cables or with exposed outside wiring (such as aerial cables).

The Z3A series of ADUs offer the following features:

● Provide an interface to the digital switch from RS-232C device.

● Increases			the distance RS-232C signals can travel over				standard twisted-pair wiring.
Refer		to	Section 5, “Technical Specification” for distance limitations.
● Data	and		control signals can be transmitted		2,000	feet	in asynchronous full-duplex
mode		at	speeds	up to 19,200 bps. The transmission		speed automatically matches		that
of the		attached		RS-232C device.
● The	DC		isolation via opto-couplers ensures		high noise		immunity, resulting in	very
low	error		rates.

●A variety of Z3AS with different connectors allows easy connection to RS-232C

terminals, printers, and host computers (see Table 4-F).

●Most Z3AS can be powered from the RS-232C interface. The ADU requires 7 volts on pin 20 (DTR) to operate properly. If the RS-232C equipment cannot meet this requirement, a low-voltage power transformer and adapter(s) must be connected. Z3A5 ADUs always require supplemental power.

●An analog single-line voice terminal (2500 or 7100 series) or a 7300H series multiline voice terminal (Z3A5 ADU required) can be connected to the ADU, allowing the voice terminal and DTE to share a common wall jack and 4-pair cable run back to the SIP.

Note: Neither off-premises nor out-of-building service can be provided with ADUs.

For additional information on ADUs, see Z3A Asynchronous Data Unit User Manual (555- 401-701).

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