Although there are guidelines for many programming languages, these are nearly non-existent for the important area of industrial control, e.g. IEC 61131-3 and its PLCopen extensions. Nevertheless, the software in the industrial environment is becoming more and more important, the software projects are larger, and the costs of errors increase.

Software nowadays absorbs half of the initial project costs and between 40 and 80% deals with maintenance over the life cycle costs of the software. To deal with the complexity of larger programs one needs modern software development processes supporting a structured approach and creating re-usable code. Also, we need to increase the efficiency in coding via re-use of pre-defined functionalities and to help to better understand the program over the life cycle.

PLCopen supports this goal via their initiative Software Construction Guidelines. The key topic is the definition of Rules, Coding Patterns and Guidance, and how to use them in Industrial Automation. Within this activity several sub-groups are identified, and the first results have been published and very well accepted in the market. The results of the working group are based on the IEC 61131-3 1st and 2nd edition but should be easily extensible to the 3rd edition of the standard that was released in 2013.So far 4 documents have been published:

• PLCopen Coding Guidelines
• Creating PLCopen Compliant Libraries
• PLCopen Structuring with SFC do’s and don’ts
• PLCopen Guidelines for Object Oriented Programming
• PLCopen OOP - application example for Motion Control
• PLCopen Guideline on Software Quality Metrics

You will find more information on the PLCopen Software Construction Guidelines on our website:
https://plcopen.org/software-construction-guidelines.