Safety of Digital Communications in Machines

Jarmo Alanen, Marita Hietikko, Timo Malm

    Research output: Book/ReportReport


    The utilisation of digital communications in safety-related machine control systems has been widely extended during the last ten years. This new technology brings about an additional safety engineering challenge compared to a single controller case where only simple wired communication is needed to execute safety-related functions. The scope of this report is safety-related serial communications in machine automation. Standards and guidelines that include information dealing with safety-related communications and the design of safety-related communication systems are introduced. The typical message error types or threats relating to serial mode transmission as well as defence methods against these threats are also introduced. There are several safety buses available for safety-related machine and automation applications. The basic information about these safety buses is given in this report. This information includes methods against possible transmission errors. Most of the safety bus solutions are commercially available from several suppliers. Some safety bus solutions that are not commercially available are also described. A documentation and analysis tool to support the safety analysis of bus-based communication systems at signal level is presented. The tool is based on database software, and the analysis method is based on Hazard and Operability study (HAZOP). This tool was developed within this project and tested with two case studies consisting of distributed control systems in machine automation applications. The advantages of using this tool are presented. A serial mode wireless communication is gaining ground in safety-related machine applications, and therefore the wireless message transmission is also considered. It was noticed that the safety analysis framework described in this report is applicable in the case of wireless communication as well. Wireless communication does not bring any new message error types; only the probability of the error types will possibly change. Therefore, the same defence methods against message errors are also true in the case of wireless systems.
    Original languageEnglish
    Place of PublicationEspoo
    PublisherVTT Technical Research Centre of Finland
    Number of pages98
    ISBN (Electronic)951-38-6503-7
    ISBN (Print)951-38-6502-9
    Publication statusPublished - 2004
    MoE publication typeNot Eligible

    Publication series

    SeriesVTT Tiedotteita - Meddelanden - Research Notes


    • serial mode transmission
    • safety-related communications
    • safety bus
    • machines
    • HAZOP


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