Component designs to satisfy functional safety standards
programming and personnel training. However, their digital electronics allow for automation functions that are fully configurable via software. Engineers can define zones needing safety coverage and modify their settings without the need to rewire the entire workcell. (That in turn trims wiring hardware and labor costs.) Usually, safety-controller- based installations also support network expansion and IIoT connectivity as operations evolve.
Integrated safety on safety-rated industrial controls
A third option for failsafe safety control that’s increasingly common in sophisticated machinery is integrated safety PLCs, programmable automation controllers (PACs), and other PC-based controls. Some such electronics hardware can assume safety functions in addition to everyday machine functions. The result is programmable and therefore flexible control over both automated machine equipment and the safety functions their operations require. Conclusion Sufficient machine safety relies on feedback and control components rated to provide protections commensurate with a given application’s hazards. Machine safety also requires proper component integration, documentation, and validation. The latter ensures safety circuits work correctly for all machine operation modes, even during faults. IEC 61508 and 62061 safety-lifecycle standards define how safety integration is correctly executed — from initial risk assessment and design to real-world verification of an installed system’s performance by the OEM and again by or for the end user once the machine is installed. The latter puts machines “through the paces” with tests of normal operation sequences, slowdowns, stops, and reset routines.
Figure 5: Safety controllers can unify multiple safety functions for flexible and reconfigurable safety installations. In the workcell illustrated here, the first safety circuit includes a light curtain that (upon reporting an interrupted status) opens a circuit switch to stop the turntable. The second safety circuit integrates muting controls that let the robot operate normally if a workpiece enters the workcell when the turntable is stopped. Otherwise, this circuit opens a switch to disable the robot. The third safety circuit includes an emergency stop that opens all switches and stops both turntable and robot. (Image source: Panasonic Industrial Automation Sales)
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