Thesis (MScEng)--University of Stellenbosch, 2001. / ENGLISH ABSTRACT: One of the main subsystems of SUNSAT is the Attitude Determination and Control System (ADCS), responsible for the orientation and positioning of the satellite. Due to the integrated architecture of the system, several shortcomings were identified. A possible solution to the problems is the implementation of a distributed system. The design of a communication protocol for a distributed system is the focus of this thesis. An investigation on different network topologies and communication protocols as well as error control techniques is carried out to establish a combination that meets the requirements of the ADCS. Based on defined protocol specifications a detailed protocol design is proposed. Then the protocol is implemented using a layered software structure that emanates from the OSI layering model, to provide well defined software structures and interfaces. A series of measurements have shown that the protocol meets the functional requirements of the ADCS and further provides reliable data transfer on the network. / AFRIKAANSE OPSOMMING: Een van die vernaamste dele van SUNSAT is die "Attitude Determination and Control System" (ADCS) wat verantwoordelik is vir die orientasie en posisionering van die satelliet. Verskeie tekortkomminge as gevolg van die geYntegreerde argitektuurvan die stelsel, is geYdentifiseer. 'n Moontlike oplossing vir die probleme is die implementering van 'n verspreide stelsel. Die ontwerp van 'n kommunikasie protokol vir 'n verspreide stelsel is die fokus van die tesis. 'n Ondersoek na verskeie netwerk topoloqie en kommukasie protokolle, asook foutbeheer tegnieke is uitgevoer om vas te stel watter kombinasie die ADCS se vereistes sal bevredig. 'n Gedetaileerde protokol ontwerp is voorgestel gebaseer op gedefineerde protokol spesifikasies. Hierdie protokol is toe geYmplementeer deur gebruik te maak van vlak gestruktureerde sagteware wat afkomstig is van die OSI model, met die oog op goed gedefineerde sagteware strukture en koppelvlakke. 'n Reeks meetings het aangedui dat die protokol die funksionele vereistes van die ADCS bevredig en dat dit verder betroubare data verplasing oor die netwerk verskaf.