Abstract
NIST started working with industry and the Institute of
Electrical and Electronics Engineers (IEEE) in the mid 90’s
to develop a standardized interface to network smart sensors.
With the spread of wireless technology, more industries are
looking to incorporate wireless communications into their
products and manufacturing processes. This paper discusses
the IEEE 1451 standard interface for smart sensors,
emerging wireless communication technologies, and possible
solutions for creating a wireless interface for the IEEE 1451
standard.
1. Introduction
Sensors are an essential component of closed-loop control
systems. They are used in all industries for all types of
applications from monitoring a machine tool in a
manufacturing plant to control of a process in a chemical
plant.
Traditionally, using sensors meant that long cables were
needed to connect each sensor back to a centralized
monitoring or control station. Each cable may have
contained multiple wires for both power and sensor data.
When working with a small number of sensors, this may not
seem like a daunting task to wire, but consider the number of
sensors in some practical applications. For example, dozens
of sensors may be used to monitor various thermal
parameters in a manufacturing facility; thousands of sensors
monitor the heat shield tiles on the Space Shuttle; tens of
thousands of sensors monitor current naval vessel’s condition
and performance.
By networking sensors together similar to linking personal
computers via a local area network (LAN), it is possible to
connect many sensors via a single cable or bus. All sensor
data can be sent through this cable using network
communication protocols. Each sensor node on the bus, like
a computer on a LAN, can easily be detached without
affecting the other sensor nodes. This makes installation and
upgrading the sensors much easier.
However, the conventional way of networking sensors
means that the centralized controller polls all the sensors and
processes all the sensor data in real time. Each sensor might
only have a small amount of data to transmit over the bus, but
if there are hundreds or thousands of sensors over the same
bus, it can cause a bottleneck for the sensor data. By
increasing the intelligence of the sensors, such as having
them perform signal processing, algorithm execution, or
decision processing, control functions are moved down to the
sensor level. Taking this approach, only processed sensor
data, control commands, and status information is transmitted
over the bus. As a result, the amount of data on the bus is
greatly reduced, decreasing the bandwidth requirements for
the network or allowing more sensors to be added. This
approach, referred to as distributed measurement and control
[1], takes full advantage of the benefit of smart sensor
networking.
NIST started working with industry and the Institute of
Electrical and Electronics Engineers (IEEE) in the mid-90’s
to develop a standardized interface to network smart sensors.
Last year, an exploratory project was initiated at NIST to
study the feasibility of adopting wireless communication
technologies and standards for networking wireless smart
sensors.
2. Background
2.1 IEEE 1451 Smart Sensor Interfaces
In March 1994, NIST and IEEE's Instrumentation and
Measurement Society’s Technical Committee on Sensor
Technology sponsored a workshop in Gaithersburg, MD to
discuss smart sensor communication interfaces and the
possibility of creating a standard interface. The response was
to establish a common communication interface for smart
transducers. Since then, four more workshops have been held
and four technical working groups have been formed to
address different aspects of the interface standard.

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