As industrial software becomes more widely used and software projects become larger, the costs of errors are mounting. According to PLCopen, software currently accounts for half of initial project costs and 40–80% of lifecycle costs.

To deal with large, complex programs, users need software development processes that support a structured approach. It is also necessary to improve coding efficiency by re-using pre-defined functions.

PLCopen held an initial meeting on coding conventions in June which resulted in several working groups being set up on topics including: coding guidelines (including naming conventions and rules); software quality issues and consistency; creating PLCopen-compliant function blocks; and software development processes.

The coding conventions working group is defining rules, patterns and guidance and advice on how to use these in automation. The rules will be published as a technical document and marketed by PLCopen.

The results will be based on the first two editions of IEC 61131-3, but should be extensible to the third edition which was released in February 2013.

The aim is to define a set of rules and suggest how these rules can be used. While larger automation companies have their own rules, the PLCopen guidelines are expected to appeal to mid-size companies and to IEC 61131-3 novices. They are also expected to be useful for training and helping to teach IEC 61131-3 programming more efficiently.