Teaching open standards for PLC programming

The need for standardisation in PLCs was first addressed in the 1970s. The International Electrotechnical Commission (IEC) produced the first draft of a standard for programmable control systems, IEC 1131, in 1979. IEC 1131-3 is much more than just a standard for PLC programming languages, it also brings many well developed software engineering ideas into the realm of PLCs. The complexity of industrial control software is increasing exponentially and proper software engineering is essential for producing robust, reliable and reusable software. The technique developed at Manchester Metropolitan University for teaching PLC applications is to use simulated processes for which students develop and test their control programs. The simulations are written in one or more of the IEC standard languages and run on ISaGRAF on the simulated PLC