The two-part installment introduces safety instrumented systems (SIS) and outlines specific tips on designing, developing, and verifying SIS applications.
Part one of this article outlined the purpose and application of the safety instrumentedsystem (SIS) as well as specific nuances with the safety integrity layer (SIL) calculations and general tips to consider when designing, developing and verifying a safety instrumented system. Keep in mind that the SIS is used for safety, not basic control. While the basic process control system (BPCS) is the workhorse of automation, the SIS is the last line of defense for the process and intended as a critical shutdown system. This second and final installment of the article wraps up by exploring tips for SIS hardware and the control system interface.