Datacom module 4: Fundamentals of Data Communication

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Data Link Control Protocol

Module 4Fundamental Concepts of Data CommunicationsChapter 22Electronic Communications Sytems , Fifth EditonBy: Wayne TomasiECE @Saint Louis University, Baguio City1Prepared by: Engr. Jeffrey Des B. BinwagData Communication CodesBaudot CodeASCII (American Standard Code for Information Interchange)EBCDIC (Extended Binary Coded Decimal Interchange Code)Bar CodesCode 39UPC (Universal Product Code)

ECE @Saint Louis University, Baguio City2Data Communication CodesCategories:Alphanumeric CharactersGraphic Control CharactersData Link Control Characters

ECE @Saint Louis University, Baguio City3Error CodingError Detection. Involves monitoring data transmission and determining when errors have occurred.Redundancy Checking: VRC and/or LRC, CRC, ChecksumHamming CodeError Correction. Involves the correction of messages that have been determined by error detection codes to contain errors at the receiver.RetransmissionForward Error Correction: VRC/LRC, Hamming CodeSymbol Substitution

ECE @Saint Louis University, Baguio City4Character SynchronizationCharacter Synchronization. Involves identifying the beginning and end of a character within a message or an extended bit sequence. Asynchronous Serial Data. Also known as start-stop transmission because each data character is framed between start and stop bits so that time gaps in between characters do not present a problem.Synchronous Serial Data. Generally involves transporting serial data at relatively high speeds in group of characters called blocks or frames with no lapses in between characters. A unique synchronization character is transmitted at the beginning of each message block as opposed to providing start and stop bits per character.

ECE @Saint Louis University, Baguio City5Bit SynchronizationBit Synchronization. A process that ensures the transmission and reception of the same number of bits without errors and in the correct order without considering the relation of each bit to adjacent bits as part of a character or message. Such procedures include correct sampling as well as proper start-bit verification.ECE @Saint Louis University, Baguio City6Data Communications HardwareAll endpoints in a data communication network have three fundamental components namely:Data Terminal Equipment (DTE). Any binary digital device that generates, transmits, receives, and/or interprets data messages. (i.e.: LCU, STACO, ACIA, UART, USRT)Data Communication Equipment (DCE). These are equipment that interfaces data terminal equipment to the transmission channel. (i.e.: MODEM)Serial Interface. A communication line that ensures the orderly flow of data between a DTE and DCE. (i.e.: USB, RS 232)ECE @Saint Louis University, Baguio City7Two-point Datacom CircuitECE @Saint Louis University, Baguio City8

Data Communications HardwareECE @Saint Louis University, Baguio City9

Universal Asynchronous Rx/TxECE @Saint Louis University, Baguio City10

UART FUNCTIONSParallel-to-serial at the Tx and Serial-to-parallel conversion at the RxError detectionFramingFormattingStatus monitoringVoltage level conversion/matchingBit and character synchronizationECE @Saint Louis University, Baguio City11UART Control WordECE @Saint Louis University, Baguio City12

UART TransmitterECE @Saint Louis University, Baguio City13

UART ReceiverECE @Saint Louis University, Baguio City14

UART Receiver Start-bit VerificationECE @Saint Louis University, Baguio City15

USRT Sampling ErrorECE @Saint Louis University, Baguio City16

USRT FUNCTIONSParallel-to-serial at the Tx and Serial-to-parallel conversion at the RxError detectionSynchronizationFormattingStatus monitoringVoltage level conversion/matchingBit and character synchronizationECE @Saint Louis University, Baguio City17QUIZ 2 COVERAGEAll Discussions in the book by Tomasi covering the following topics:Datacom CircuitsSerial and Parallel Data TransmissionDatacom Circuit ArrangementsDatacom NetworksComponents, Functions, and FeaturesModelsTopologiesClassificationsDatacom CodesError CodingCharacter and Bit SynchronizationDatacom HardwareDatacom CircuitsUART and USRT

ECE @Saint Louis University, Baguio City18