Programmable logic controller: Difference between revisions

Revision as of 10:50, 12 February 2022

Revision as of 07:29, 13 February 2022

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== Safety PLCs ==

In recent years "safety" PLCs have become popular, either as standalone models or as functionality and safety-rated hardware added to existing controller architectures ([[Allen-Bradley]] Guardlogix, [[Siemens]] F-series etc.). These differ from conventional PLC types by being suitable for safety-critical applications for which PLCs have traditionally been supplemented with hard-wired [[safety relay]]s and areas of the memory dedicated to the safety instructions. The standard of safety level is the [[Safety integrity level|SIL]]. For example, a safety PLC might be used to control access to a robot cell with [[Trapped-key interlocking|trapped-key access]], or perhaps to manage the shutdown response to an emergency stop on a conveyor production line. Such PLCs typically have a restricted regular instruction set augmented with safety-specific instructions designed to interface with emergency stops, light screens, and so forth. The flexibility that such systems offer has resulted in rapid growth of demand for these controllers.<ref>{{Cite web|url=https://fcbuy.ir/|title=PLC |date=2022-02-13|website=industrial Automation |access-date=2022-02-13}}</ref>

==PLC compared with other control systems==