What Are Safety PLCs?

Programmable logic controllers (PLCs) are designed for the automation and control of industrial plant and equipment. Safety PLCs do all this and more: they support all the usual applications controlled by a standard PLC, with the addition of integrated safety functions designed specifically for the control of safety-related systems. A safety PLC has only two important objectives to accomplish. Firstly, it should not fail. Secondly, if failure can't be avoided, it should only happen in a safe and predictable way.

These objectives are achieved through the Safety PLC's redundant microprocessors. Nearly all telecommunications and wireless equipment now contains these standby processors as a back-up, which eliminate the requirement for safety relays. The design of Safety PLCs also incorporates built-in diagnostics that allow for continuous monitoring of the various inputs and outputs. The PLC will be safely shut down in the event of its detecting any internal fault or failure.