First came IEC 61131, which was created and finalized in 1992 to help simplify and speed the programming of programmable logic controllers (PLCs). Its development was prompted by the manufacturing industry, which was seeking to create production systems that were more flexible and reconfigurable.
IEC 61499 was later developed in an attempt to provide a more effective plug-and-play environment for function blocks. Promulgated in 2005, IEC 61499 defines a reference architecture for open, distributed control systems. Thus, a function block can be used on different processing systems and equipment, as well as being used in different programming languages. IEC 61499 allows function blocks that encapsulate software functionality.
Using a standard can greatly reduce the amount of training needed, especially if that standard is taught outside the manufacturer’s facility. Those manufacturers using the IEC standards can now hire engineers who have been trained on the standard. “If an engineer goes to a PLC brand school or a tech college that provides 61131 courses, the engineer can use that at any plant that utilizes 61131,” says Rich Hutton, automation product manager at Schneider Electric, in Palatine, Ill. “The engineer becomes more efficient, and the learning curve is short, which means the job gets done earlier.”
The standard also allows manufacturers to use the same code in different environments and languages. “You can use 61131 programming to set up the same functionality in several different languages,” says Joe Biondo, e-business manager at Bosch Rexroth Corp., in Hoffman Estates, Ill. “The 61131 standard also allows end-users to see ladder logic without having to think about the code.”
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