N-GEN Communications Web-based Seminars ©NGCS

Seminar - An Overview of Communications Technologies

Module 2 - Data Communications Basics and Legacy Technologies                                                Slide 21 of 45 _________________                                                                                  __________

                                                  Interface Types

                                                Contact Closure

                                                Voltage

                                                System / Network

                                                Protocol Converter

_________________                                                                                  __________

Many types of interfaces are available in the marketplace for DTE, DCE, Network and Protocol converters. These interfaces are defined by the standard bodies and implemented by the equipment and software developers in their products. Interfaces define physical connection and electrical signals to be transmitted between two systems. Interfaces convert electrical signals or software components so that they are acceptable to other systems. They also make one device operable with another device.

Contact Closure Interface - 20 milli amps current interface

Voltage Interface - EIA-series standards defined by Electronic Industries association. RS - 232C is one of the well known standards to interface data terminals to the data sets. V - series standards defined by International Consultative Committee (CCITT), now known as International Telecommunications Union (ITU). V.34+ standard known for 33.6 K bps full duplex operation.

System / Network Interface: Data Link Control (DLC), Higher Level Protocols and OSI layers are the examples of this interface. Binary Synchronous Communications (BiSync) and Synchronous Data Link Control (SDLC) from IBM are examples of Data Link Control interface between two systems. Systems Network Architecture (SNA) from IBM, X.25 from CCITT and OSI layers from International Standards Organization are the examples of Higher Level Protocol interface between two systems.

Protocol Converters - provide interface between two dissimilar systems and networks. The example of this is to map ATM into SONET protocol. A protocol converter can be implemented by hardware or software.