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P1451.3 Working Group

The IEEE P1451.3 Working Group was formed to develop a smart transducer interface standard for distributed multi-drop transducer bus for a network. This standard introduces the concept of a Transducer Bus Interface Module (TBIM) and a Transducer Bus Controller (TBC) connected by a Transducer Bus. A TBIM is a module that contains the bus interface, signal conditioning, Analog-to-Digital and/or Digital-to-Analog conversion and in many cases the transducer. A TBIM can range in complexity from a single sensor or actuator to units containing many transducers (sensors and actuators). A TBC is the hardware and software in the NCAP or host processor that provides the interface to the Transducer Bus. The Transducer Bus provides the communications path between an NCAP or host processor and one or more TBIMs. Three types of transducers are recognized by this standard. They are sensors, event sensors and actuators.

The IEEE 1451.3 standard defined a set of specifications that will allow a transducer manufacturer to build transducers that have a wide range of price and performance but which are all inter-operable within a system. The standard allows for simple devices with relatively low data sampling rates and moderate time correlation requirements to be designed and built. At the other end of the spectrum devices that have bandwidth requirements to several hundred kilohertz and time correlation requirements in the range of nanoseconds can be built based on the standard. It is expected that devices from either end of the spectrum will be able to peacefully coexist on the same bus. Figure 1 is a representation of what is expected in the physical realm. As shown in the diagram, a single transmission line will be used to supply power to the transducers and to provide the communications between the bus controller and the Transducer Bus Interface Modules (TBIM). A bus is expected to have one bus controller and many TBIMs, up to 255 modules. The Network Capable Application Processor (NCAP) contains the controller for the bus and the interface to the broader network that may support many other buses. A TBIM may contain one or more different transducers, up to a mix of 255 sensors and actuators.

Physical representation of the IEEE 1451.3
Figure 1.  Physical representation of the IEEE 1451.3