AT&T 7100 series, 7500 series, 2500 series DTE Connections, DTE Compatibility, Protocol Converters

DTE CONNECTIONS

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Through your communications system, you can communicate with both asynchronous and synchronous DTEs. The DTEs may include terminals and personal computers, as well as host computer ports. Designing these connections is a multi-step process:

∙First, you must determine whether the DTEs are compatible. Asynchronous terminals must communicate with asynchronous hosts, unless protocol converters are inserted in the communications stream, or special terminal emulators or data communications packages are used.

∙Second, you must be aware of the possibilities in data communication equipment (DCEs), like modems and data modules, you can install.

∙Third, you must decide which DCEs are appropriate for your installation. The DCE you choose will depend on the communications system ports you use, the communications characteristics of the DTEs (for example, asynchronous vs synchronous, full duplex vs half duplex, data speed, and so forth), and the desk-top profile (standalone DCE, intergrated DCE/voice terminal) you want for your DTE/DCE combination.

∙Last, you must identify whether the communicating DTEs require modem pooling in the connection. To communicate with an off-premises DTE, modem pooling may be required to convert signals between digital and analog. Similarly, DTEs that are communicating in different transmission modes (that is, one DTE is using analog transmission, the other digital transmission) require modem pooling, regardless of whether they are on the same site.

DTE COMPATIBILITY

You can solve the connectivity problems of incompatible DTEs by:

∙Installing protocols converters between the originating and destination DTE.

∙Running a terminal emulation application, provided as a standalone application or integrated into a data communications package, on the personal computers and/or hosts that you want to communicate with each other.

∙Installing the PC/PBX or PC/ISDN Platform in your IBM XT/AT compatible personal computer.

Protocol Converters

Many vendors offer protocol converters that convert messages, for example, between the asynchronous and synchronous formats, between ASCII code and IBM’s SNA/SDLC protocols, and so forth.

Currently, for protocol conversion, AT&T offers only the 3270C data module. The 3270C, which converts DCP protocol to coax-A protocol, allows a PC equipped with the PC/PBX 3270 emulation package to communicate with an IBM 3270 cluster controller through the switch over a twisted pair connection.

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