Analysis of profibus communication using process automation and decentralised periphery against conventional (4-20MA)

The research Analyses, PROFIBUS Communication using Process Automation and Decentralized Periphery against Conventional (4-20mA) was based on the process plant constructed in 2012 by staff and students in the Department of Instrumentation and control at Mangosuthu University of Technology. Further work was not done including configuring the entire process plant, testing all devices and display the image of the process plant on human machine interface. The process plant operation was never tested and the research topic has not been attempted before. The research was conducted to improve the existing plant to full operation or functional project. The research study was conducted in March 2013 by BZT Ntshangase, it was established that both DP flowmeter and PA flowmeter were not tested before, not calibrated correctly and both drives which are (MM440 and MM420) were not setup to control both pump1 and pump 2 in manual or auto mode. The Programmable Logic Controller (PLC) was not configured to communicate with all devices on the network. PROFIBUS-DP and PROFIBUS-PA devices were not set up; input measurements were not scaled to read within certain limits. All devices used in the process plant were not assigned unique addresses for the network and DSG files were not installed so that Programmable logic controller (PLC) would identify all devices on the PROFIBUS network. The research was based on analysis of PROFIBUS communication using process automation and decentralized periphery against conventional (4-20mA), where one flowmeter was communicating with a PLC via PROFIBUS-DP and the other flowmeter was communicating through PLC via ET-200M to a DP/PA coupler. Research objective was to examine the time response between the two signals, data transmission, network configurations and their communication protocols and including transmission rate for both networks. Process plant components used in the research were tested for linear scaling, reliability, generalizability and validity. The reason for performing these tests was to produce consistent results and to checks how similar results are if the research was repeated under similar circumstances. During testing, respectable results were achieved. All simulated results were compared with the real-time results and then a conclusion drawn based on the obtained information and facts. Project design, implementation, test procedures and test results were achieved because prototype performed as per design and research objectives were achieved. Simulation tests were conducted and the obtained results analysed. The achieved results showed that the proposed solution or the prototype system performed as per design. The experimental results could be useful to other researchers in the future. At the end of the study conclusion and some recommendations for further studies are discussed efficiently to utilize resources in the process plant verification and validation.Electrical EngineeringM. Tech. (Electrical Engineering

Verification of PLC properties based on formal semantics in Coq

Programmable Logic Controllers (PLC) are widely used in embedded systems for the industrial automation domain. We propose a formal semantics of two languages defined in the IEC 61131-3 standard for PLC programming. The first one is the Instruction List (IL) language, an assembly like language. The second one is the Sequential Function Charts (SFC) language, a graphical high-level language that allows to describe the main control-flow of the system. A PLC system description may comprise SFC and IL code. We formalized the semantics in the proof assistant Coq. Furthermore, we present an associated tool for automatically generating SFC representations from a graphical description - the text based IL code can be handled in Coq directly - and its usage for verification purposes. We demonstrate our approach to prove safety properties of a PLC in a real industrial demonstrator

Verification of PLC Properties Based on Formal Semantics in Coq

International audienceProgrammable Logic Controllers (PLC) are widely used in embedded systems for the industrial automation domain. We propose a formal semantics of two languages defined in the IEC 61131-3 standard for PLC programming. The first one is the Instruction List (IL) language, an assembly like language. The second one is the Sequential Function Charts (SFC) language, a graphical high-level language that allows to describe the main control-flow of the system. A PLC system description may comprise SFC and IL code. We formalized the semantics in the proof assistant Coq. Furthermore, we present an associated tool for automatically generating SFC representations from a graphical description - the text based IL code can be handled in Coq directly - and its usage for verification purposes. We demonstrate our approach to prove safety properties of a PLC in a real industrial demonstrator