02 - Codesys: Hardware-independent SIL3 safety controller
With Codesys Virtual Safe Control SL, it will soon be possible to implement SIL3-certified safety controllers without certified hardware. For more than ten years, the Codesys automation software from the company of the same name has been able to be expanded with a certified SIL3 solution based on two-channel, certified hardware with 1oo2 safety channel architecture (one out of two). The hardware can now be abstracted using virtual controllers. The software solution creates dual-channel capability through "Diversified Encoding", which is based on "Coded Processing". The processing of applications is divided into two logical software channels. The first channel executes the original security application, while the second executes the same application using coded processing algorithms, enabling it to detect errors. Both channels run sequentially one after the other in a CPU core and are constantly comparing themselves so that data and control flow errors are detected more frequently. Diversified encoding distributes secure inputs to both channels and, conversely, outputs from both channels are merged into secure outputs. Data streams generated by secure network or fieldbus protocols are enclosed and addressable in real time. This represents an equivalent solution to physical systems without being tied to hardware.