Practical Industrial Data Networks:Design, Installation and ...

Appendix A – Glossary 309MOSMOVMSBMSDMTBFMTTRMultidropMultiplexer (MUX)metal oxide semiconductormetal oxide varistormost significant bits – the digits on the left-hand side of thewritten HEX or BIN codesmost significant digitmean time between failuresmean time to repaira single communication line or bus used to connect three ormore pointsa device used for division of a communication link into twoor more channels either by using frequency division or timedivisionNAKNetwork architectureNetwork layerNetwork topologyNetworkNMRRNodeNoiseNOSNRMNRZNRZINull modemnegative acknowledge (ASCII Control-U)a set of design principles including the organization offunctions and the description of data formats and proceduresused as the basis for the design and implementation of anetwork (ISO)layer 3 in the ISO/OSI reference model, the logical networkentity that services the transport layer responsible forensuring that data passed to it from the transport layer isrouted and delivered throughout the networkthe physical and logical relationship of nodes in a network;the schematic arrangement of the links and nodes of anetwork typically in the form of a star, ring, tree or bustopologyan interconnected group of nodes or stationsnormal mode rejection ratioa point of interconnection to a networka name given to the extraneous electrical signals that may begenerated or picked up in a transmission line – if the noisesignal is large compared with the data carrying signal, thelatter may be corrupted resulting in transmission errorsnetwork operating systemunbalanced normal response modenon return to zero – pulses in alternating directions forsuccessive 1 bits but no change from existing signal voltagefor 0 bitsnon return to zero inverteda device that connects two DTE devices directly by emulatingthe physical connections of a DCE deviceNyquist sampling theorem in order to recover all the information about a specified signalit must be sampled at least at twice the maximum frequencycomponent of the specified signalODOhm (W)Optical isolationobject dictionaryunit of resistance such that a constant current of one ampereproduces a potential difference of one volt across a conductortwo networks with no electrical continuity in their connectionbecause an optoelectronic transmitter and receiver has beenused