Emerson DeltaV SIS Logic Solver (SLS1508)

Emerson DeltaV SIS Logic Solver (SLS1508)

Core positioning and core advantages

The DeltaV SIS Logic Solver (SLS1508) is the core component of Emerson's Intelligent Safety Instrumented Systems (SIS), designed specifically for industrial process safety protection and meeting SIL 1-3 safety functional requirements. Its core advantages can be summarized into six key features:

The world's first intelligent SIS logic solver: communicates with intelligent field devices through the HART protocol to diagnose faults in field instruments and final control components in advance (according to research, such faults account for more than 85% of SIS faults), avoiding false tripping, improving process availability, and reducing full lifecycle costs.

Integrated but independent with the control system: strictly follow safety standards, use dedicated hardware, software, and networks to implement safety functions, and eliminate the impact of common cause failures; Simultaneously achieve seamless integration of configuration, maintenance, and operating environment at the workstation level, balancing security and usability.

Easy to comply with IEC 61511 standard: provides strict user management functions, automatically verifies data for changes initiated by the human-machine interface (HMI) (such as trip limit modification), ensures accurate data writing into the target logic solver, and meets the strict requirements of the standard for change control.

Suitable for any scale of application: Whether it is an isolated wellhead or a large emergency shutdown (ESD)/fire and gas system, it can be flexibly expanded to cover SIL 1-3 safety functions; Each logic solver is equipped with dual CPUs and 16 I/O channels, allowing for system expansion without the need for additional processors. The scanning rate and memory usage are not affected by system size and remain stable.

SIL 3 certification and redundant architecture: The SLS1508 logic solver meets SIL 3 application requirements with a single unit, and the availability is higher when installed in pairs with redundancy; The redundant architecture includes dedicated redundant links, independent power supply, I/O redundant peer-to-peer links for real-time release, and dual machine shared input data to ensure reliable system operation.

Support for online addition of logic solvers: The system automatically detects new hardware every scanning cycle and can add devices to the online system in real-time without interrupting the process; Once the newly added device is recognized by DeltaV Resource Manager, it can be directly configured, greatly improving the flexibility of system expansion.

Core components and functional details of the product

（1） Core hardware components and system architecture

Component Name Function Description Key Features

SLS1508 logic solver core safety logic operation unit, provides I/O interface with built-in dual CPU, 16 configurable I/O channels (discrete input/output, analog input (HART), HART dual state output), supports single SIL 3 application, and occupies 4 slots for redundant paired installation

The redundant terminal block connects the on-site wiring and logic solver to adapt to the SLS1508 redundant architecture, enabling redundancy without the need for additional control strategy configuration. The system automatically identifies redundant pairs

SISnet repeater extends the communication range of SISnet and realizes remote logic solver communication through fiber optic ring network. It is divided into two independent fiber optic rings, primary and backup. Please refer to the separate product manual for details

The carrier extension cable extends the local bus power and signal connection between 8-wide carriers, ensuring signal transmission between the controller, logic solver, and SISnet repeater

Local peer-to-peer bus extension cable extends SISnet communication between logic solvers on different carriers, supports interconnection of logic solvers across carriers, and builds a local SISnet network

The wide terminal carrier terminates the local peer-to-peer bus installed at the end of the carrier chain, providing SISnet bus terminal matching to ensure stable communication

The 8-width carrier carries logic solvers, SISnet repeaters, and other components. The logic solvers are installed in odd numbered slots (1/3/5/7) and support connecting multiple carriers through expansion cables

（2） Communication Network Design

Control Network: Implement communication between DeltaV network nodes, as detailed in the DeltaV Digital Automation System Installation Manual.

Local Bus: connects DeltaV controllers with logic solvers, SISnet repeaters, and transmits control and configuration signals.

Local Peer to Peer Bus (SISnet): a dual channel bus where logic solvers communicate with each other and with local SISnet repeaters through a carrier, and the same message is broadcasted on both channels; The two ends of the bus need to be terminated (the left end through a 2-wide power/controller carrier, and the right end through a 1-wide terminal carrier), and the repeater can be flexibly installed at any position on the bus.