AT&T System 85 manual 7400B and 7400B Plus Data Module, Applications

7400A Data Module

7400B and 7400B Plus Data Module

The 7400B and 7400B Plus Data Modules are full-duplex asynchronous, Hayes® Compatible data modules that provide for simultaneous voice-data communications at the desk top over stan - dard twisted pair wiring. The 7400B data module has been discontinued; however, the 7400B Plus data module has all of the basic characteristics of the 7400B, with the following added bene- fits:

Supports the semicolon dial modifier, which enables an automatic return to the command mode after dialing a data call;

Offers a storable S7 register, which supports increased call set-up time;

Offers the voice dial capability, which provides the ability to dial a voice call from the PC package in the attached PC.

Both of these data modules replace the existing PDM (MPDM) for asynchronous communication, DTDM, and data stands for 7406D and 7407D voice terminals (703A DSU and 702AL1) and the 7404D integrated voice/data phone.

In the linked mode, the 7400B and 7400B Plus data modules provide for simultaneous voice data communications over standard twisted pair wiring. In this mode, the 7400B and 7400B Plus data modules can be used with all DCP voice terminals to provide data service. The 7400B Plus pro- vides the voice dial feature for all DCP voice terminals except the following:

7403D voice terminal (all models)

7404D voice terminal (all models)

7405D voice terminal (all models)

7407D01A voice terminal

Applications

The 7400B and 7400B Plus data modules can be used with the DEFINITY Communications Sys- tem G1, G2, G3, System 75, and System 85. The data modules are used as a DCE for host access services, PC, or terminal (DTE) connectivity (see Figure 2).

Figure 2 shows a diagram of the connections between the 7400B or 7400B Plus and the data terminal, the digital voice terminal, and the switch.

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