| Autor: |
Fencott, Clive, Fleming, Colin, Gerrard, Chris |
| Zdroj: |
IFAC-PapersOnLine; October 1992, Vol. 25 Issue: 30 p87-92, 6p |
| Abstrakt: |
We document the application of formal methods to the specification and verification of the type of process control typically used in safety critical systems. We discuss the use of an executable subset of the formal specification language OBJ to model and verify systems utilising Programmable Logic Controllers (PLCs) prior to hardware implementation. We specify a stand alone PLC. a common instruction sub-set, and a complete “test engine” combining all the main elements of a PLC, ie. I/O/program scan-I-Program + IO-History. The method integrates with existing techniques for the development of PLC programs which we specify by an abstract data type which models ladder logic. Examples are presented to demonstrate the practicality of the approach and the benefits to be gained from testing such systems in software. The role of such techniques in an industrial safety critical context are discussed, both from the point of view of systems implementation and maintenance. In conclusion we outline current work focusing on hand held tool support, additional formal verification methods, and the application of the technique to systems development within safety standards. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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