Instruction manual

HARDWARE DESCRIPTION
Asynchronous Data Units (ADUs)
Asynchronous Data Units and Multiple Asynchronous Data Units (MADUs) provide an
interface between ports on the TN726 Data Line CP and RS-232 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 ADUs (Figure 4-23 and 4-37) are DCE that allow a direct connection
between DTE and port circuits on the Data Line CP (TN726). To connect an ADU to DCE, a
cross-over cable (“null modem”) is required (PEC 2724-30C).
The modular jack labeled “Wall” connects the ADU to the building wiring with a standard 4-
pair modular cord. The 400B2 Adapter can be used to provide supplemental ac power for
the ADU and is 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-G.
The Z3A ADUs should be installed only on “inside” 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-232 devices.
● Increases the distance RS-232 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-232 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-232
terminals, printers, and host computers (see Table 4-G).
● Most Z3As can be powered from the RS-232 interface. The ADU requires 7 volts on
pin 20 (DTR) to operate properly. If the RS-232 equipment cannot meet this
requirement, a low-voltage power transformer and adapter(s) must be connected.
Z3A5 ADUs always require supplemental power.
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