With smart logic solvers (SLS), the DeltaV SIS™ architecture provides flexibility for the safety you want, when you want, where you want. The SLS hardware is modular – scaling in sizes of 16 to 30,000 configurable I/O. Memory and CPU are added with every logic solver you add, so the days of running out of memory or CPU power are over. Because of the modular approach to logic solving, adding I/O to an application can be done without affecting the response time of existing applications. DeltaV SIS is designed to be implemented in a distributed architecture, close to the equipment it is safeguarding – resulting in reduced wiring costs and system complexity.  It's approved for use in SIL 1, 2 and 3 safety applications as defined by IEC 61508.

Key capabilities of the safety logic solver include:

• 24V DC redundant power
• 16 channels per logic solver in any combination of HART AI, HART AO, DI, DO
• line detection in all I/O
• separate I/O processor CPU
• 50ms execution
• upgradable under power
• -40° to 70° temperature rating
• ISA G3 corrosive rating

To increase the availability of safety loops, redundant logic solvers can be specified. Each SLS in a redundant pair includes separate power, separate logical addresses, a dedicated redundancy link, and cyclic redundancy checks (CRCs) on every scan.