Understanding Smart Sensors - Nomads.usp

276 Understanding Smart Sensors12.3 IEEE 1451.1The IEEE 1451.1 specification provides a simple, complete object model forbuilding smart sensor and actuator-based systems [2]. In general, an object is acollection of data and operations. An object model is a definition of data structuresand operations organized in a formal specification. For IEEE 1451.1, asmart transducer object model includes an interface to a transducer objectmodel and to a transducer bus.The IEEE 1451.1 standard models a smart transducer as a software PCwith a backplane and plug-in cards [4]. The standard is intended for a manufactureror integrator that provides additional functionality in the form ofonboard intelligence that has to be supported on more than one underlyingnetwork. Figure 12.2 shows the building blocks and software components ofparameters, events, actions, files, and timers.12.3.1 Network-Capable Application ProcessorThe NCAP typically consists of a processor with an embedded operating systemand timing capability. NCAPs can range from simple elements with moreextensive support from STIMs with many channels to more complex designswith multiple ports. Figure 12.3 illustrates the top-level relations between blockobjects, software processes, and an NCAP [2]. Within an NCAP there can beseveral software processes in the function block, base transducer block, andLogical “backplane”eventactionparameterfiletimerTransducerinterfaceTransducersPhysical block:configuration andresource managementFunction blocks:Network block:applicationsmapping tocommunicationsTransducer blocks:I/O drive abstractionof hardwareFigure 12.2 Object model components for IEEE 1451.1. (After: [4].)