• Debugging and forcing are signs of a poorly written program.

• Process models can be used to completely describe a process.

• When programming large systems, it is important to subdivide the project into smaller parts.

• Documentation should be done at all phases of the project.

30.9.1 References

Eberhard, A, "Safety in Programmable Applications", Automation World, Nov., 2004.

Kenner, R. H., “The Use of Simulation Within a PLC to Improve Program Development and Testing”, Proceedings of the First Automation Fair, Philadelphia, 1990.

McCrea-Steele, R., "Proven-in-Use: Making the right choices for process safety", Hotlinks, Invensys, Summer 2003.

Paques, Joseph-Jean, “Basic Safety Rules for Using Programmable Controllers”, ISA Transactions, Vol. 29, No. 2, 1990.