Title of Invention

A DISTRIBUTED CONTROL AND/OR MONITORING SYSTEM WITHIN AN INDUSTRIAL PLANT

Abstract The invention relates to a process control system (10) utilises wireless transceivers to divorce the field devices (14,30) from traditional wired network topologies. By providing field devices (14, 30) with wireless transceivers (22) and shared wireless transceivers (36) for adapting wired field devices (30), the field device network may be adapted to any number of network topologies without concern for additional wiring costs. Specifically, a power supply (18, 26) can be provided for each field device (14) or for groups of field devices, as needed. Thus, the entire network can receive power from a single power bus (32), without expensive power filtering. In addition, the network can be a bybrid in which part of the information is transmitted and received over wired lines and part is transmitted and received over wireless communication.
Full Text The present invention relates to process control transmitters
used to measure process variables in industrial processing plants. More
particularly, the present invention relates to field devices with wireless
transceivers powered by an external common DC bus for power supply or
by an existing powercircult.
In industrial settings, control systems monitor and control
inventories, industrial and chemical processes, and the like. Typically,
the control system perform these functions using field devices distributed
at key locations in the industrial process and coupled to the control
circuitry in the control room by a process control loop. The term "field
device" refers to any device that performs a function in a distributed,
control system, including all devices currently known in the measurement
and control art.
Generally, each field device includes a transducer. A
transducer is understood to mean either a device that generates an
output signal based on a physical input or that generates a physical
output based on an input signal. Typically, a transducer transforms an
input into an output having a different form. For example, a loudspeaker
is a transducer that transforms electrical signals into sound energy.
Types of transducers include various analytical equipment, pressure
sensors, thermistors, thermocouples, strain gauges, flow transmitters,
positioners, actuators, solenoids, indicator lights, and the like.
Typically, each field device also includes a transmitter that
boosts the transducer's signal in a standard format Such transmitters
generally communicate with the control room via the process control loop.
Typically, the process control loop delivers a regulated current and/or
voltage for powering the field devices. Additionally, the process control
loop may carry encoded signals. Traditionally, analog field devices have
been connected to the control room by two-wire twisted-pair current
loops, with each device connected to the control room by a single two-

wire twisted pair loop. Typically, a voltage differential is maintained
between the two wires within a range of voltages from 12-45 voJts for
analog mode and 9-50 volts for digital mode. An analog field device
transmits a signal to the control room by modulating the current running
through the current loop to a current proportional to the sensed process
variable. An analog field device that performs an action under the control
of the control room is controlled by the magnitude of the current through
the loop, which is modulated by the ports of the process subsystem under
the control of the control room.
Discrete or digital field devices respond to a binary signals
and transmit binary information. Typically, discrete devices operate with
a 5-30 volt signal (AC or DC), a 120 or 240 volt AC signal, delivered by
the same or similar two-wire twisted pair loops. Of course, a discrete
device may be designed to operate according to any electrical
specification required by the control environment.
Generally, in industrial plants, the individual field devices
are wired to a junction box, and from there to the control room or to
marshaling racks through home run cables. Since cabling distances from
the field device to the junction box are relatively short, the bulk of the
cabling cost is in the home run cable. HART® is a well established
standard but control systems in general do not support HART® multidrop
configurations; therefore, there is little savings from wiring using the
HART® protocol. The few control systems supporting HART® generally
have limited access to device diagnostics and do not use the digital
information for control due to speed limitations.
Since communications and power typically are delivered
over the same wires, various properties must be taken into account in
order to have a successful installation, such as proper shielding against
noise, low ripple power supplies, appropriate line and power impedances,
wire length and properties, impedance, terminations, and the like. Using
the same pair of wires for communication and power also makes power
regulation of the device more complicated. Simple low pass filters cannot

be used to remove noise from the power signal because a "notch" at the
communications frequency must be allowed to bass. Specifically, the low
pass filter has a tendency to "refine" the load current, thereby reducing
ripples or notches in the AC communication signal. It is important to note
that the transmitters are basically shunt regulators that shunt between 4
and 20 mA in analog transmitters. In order to shunt on the low end (i.e. at
4 mA), the transmitter must operate at a power of less then 4 mA.
With the advent of low power wireless communications,
many new network topologies can be imagined. However, power
constraints of wireless transmitters typically limit process control networks
to the traditional wired topology. A truly wireless field device is one that
contains its own source of power, such as a battery, solar power, fuel cell,
an energy scavenging power source, and the like, and is not constrained
by traditional wired configurations.
However, such wireless transmitters suffer from the basic
problem of low available power, which tends to limit the utility of such field
devices. Specifically, the low available power forces the use of low data
rates to help conserve energy, and/or requires frequent, periodic
replacement of the power source. Transmission power also restrains the
transmitting distance.
BRIEF SUMMARY OF THE INVENTION
A system for supplying power to a plurality of field devices
has a plant-wide or field-based power bus for delivering power to each
field device. Some field devices are adapted to regulate their own power
and to communicate wirelessly with a control center. Other field devices
are connected to the network via a junction box, and the junction box is
adapted to regulate power to a cluster of field devices. The junction box
may also be adapted for shared wireless communication with the control
center. Existing process control networks may be adapted for wireless
communication by integrating a wireless transceiver with the control
center. The process control network may be entirely wireless or may be a
hybrid wired/wireless network. Each field device has a housing, a

transducer within the housing, and an electrical terminal for delivering
power to the circuit from an existing power circuit. In some embodiments,
each field device contains a wireless communications board for
communicating wirelessly with the control center. In an alternative
embodiment, clusters of fiefd devices share a wireless communication
board disposed within a junction box for communicating wirelessly with
the control center. The wireless communications boards utilize standard
communications protocols to facilitate communications between the field
devices and the control center and between various field devices. In this
manner, the system may be organized as a traditional process control
network or may be organized dynamically as a self-organizing network.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
FIG. 1 is a block diagram of a wireless field device process
control system of the present invention.
FIG. 2 is a block diagram of a wireless field device of FIG. 1.
FIG. 3 is a block diagram of distributed wireless process
control network having junction boxes adapted to deliver power to field
device's and to transmit field device data wirelessly via a shared wireless
transceiver.
FIG. 4 is a block diagram of a distributed wireless process
control network having junction boxes adapted to provide a shared
wireless transceiver to a group of field devices, each having its own
power supply.
FIG. 5 is a block diagram of a self-organizing wireless
process control network according to the present invention.
FIG. 6 is a block diagram of another embodiment of a
wireless process control network according to the present invention.
DETAILED DESCRIPTION
The present invention takes advantage of available wireless
technologies to free the process control network from its traditional wired
topologies. Wireless transceivers can be used both to adapt existing
process control networks to provide wireless communications capabilities

and to construct process control networks without costly homerun cabling -
and without expensive power filters.
In general, the wireless transceivers send and receive data
wirelessly, thereby divorcing the signaling or communications path from
the physical wiring. While conventional process control networks
provided power and signaling over the same set of wires, by handling the
power supply to the field devices separately from the signaling or
communications path in the present invention, the field devices are no
longer bound to the physical wiring of a control network. Instead, data is
transmitted wirelessly. and power is supplied to the field devices from a
variety of different means, allowing the field devices to be deployed
dynamically and to be arranged in a variety of ways.
While conventional process control networks utilized costly
power filters to maintain a tightly controlled power distribution, the
separation of the power supply from the communications path allows field
devices to be provided with their own power supply circuitry, which can be
much cheaper and less tightly controlled than conventional systems.
Thus, an entire process control network can be constructed without
expensive power filtering and with distributed field devices drawing power
from many different sources. Such sources may include batteries,
existing homerun cabling, standard plant-wide power (e.g. a wall outlet
providing conventional 120 AC power, and the like), a single charged
wire, solar power circuitry, and various other power sogrces. In general,
since the power supply does not need to be tightly regulated and since
communications Is handled wirelessly between the field devices and
control systems within the control room, any type of power supply can be
utilized to power the field devices. By powering the field devices from
power supplies that are separate from the communications path, the
process control network architecture becomes more versatile and with
lower cost, allowing for network topologies that were not previously
possible without significant investment in cabling and allowing for
inexpensive hardware components.

With the present invention, it is possible to integrate
wireless technologies with existing process control networks. Specifically,
wireless devices may be added to existing networks and existing field
devices may be adapted to transmit wireless information. Additionally,
existing cabling may be utilized differently to deliver power to field devices
(individually and in clusters), and to allow flexibility in extending or
shrinking the size of the network.
As shown in FIG. 1, a process control network 10 has a
control system 12 and a field device 14, having a power supply 16 and a
power supply circuit 18 (shown in phantom), respectively. The power
supply circuit 18 is shown in phantom to indicate that the power supply
circuit 18 may be internal or external to the field device 14. As shown,
the field device 14 communicates with the control system 12, wirelessly,
to transmit and to receive data and various signals.
Generally, the control system 12 refers to one or more
computer systems for exercising control and/or monitoring of an industrial
process. The control system 12 may be confined within a control room,
may span more than one office, or may be geographically separated and
connected via a network (such as telephone networks, the Internet, or
any other type of network). Additionally, the control system 12 Includes
both automated and user initiated control systems.
In this embodiment, the control system 12 and the field
device 14 may be powered by the same circuit or by independent power
supplies. However, by providing the field devices 14 with their own power
supply circuit 18, expensive and tightly controlled filtering is no longer
required. Nor are long wires required to power the device. Relatively -
unregulated power supplies can be used to deliver power to the field
devices 14, allowing field devices 14 to be powered with simple,
inexpensive power supplies 16,18. With the present invention, since
filtering of transmitted information not a concern with respect to the
wiring, the power supplies 16,18 can use simple filtering techniques.

It is important to note that FIG. 1 assumes that the control
system 12 is equipped or configured td transmit and receive data and
signals, wirelessiy. Additionally, the embodiment of FIG. 1 illustrates a
field device 14 with wireless transmission and reception capabilities.
FIG. 2 shows a process control system 10 having a control
system 12 and a field device 14, both capable of wireless
communications. As shown, the field device 14 has a power supply
circuit 18, which delivers power to an actuator/transducer 20 (hereinafter
referred to as "transducer 20") and to a wireless communications board
22. The wireless communications board 22 refers to circuitry for
transmitting and receiving information wirelessiy between the control
system 12 and the field device 14. tn some instances, the wireless
communications board 22 may perform other functions, such as digitizing
analog information received from the transducer 20, prior to transmission
of the information.
The transducer 20 is understood to refer to any device that
translates an input into an output having a different form from the input
(e.g. a device that generates a physical output based on an electrical
input signal or an electrical output based on a physical input signal).
Thus, the field device 14 containing a transducer 20 can be either an
input device or an output device or both. The field device 14 can contain
both input and output components in communication with the
communications board 22. For example, the field device 14 may contain
both a sensor and indicator lights or an LCD display, for sensing
information and transmitting the raw data or raw A/D count to the wireless
communications board 22, and for receiving a display signal or display
code from transceiver 24 of the control system 12 and displaying a value
on the display.
Generally, the wireless communications board 22 and the
wireless transceiver 24 are each capable of two-way, wireless
communications, allowing for two-way wireless communications between
the control system 12 and the field devices 14. The two-way wireless

communication may be completed using wireless networking
technologies (such as IEEE 802.11b wireless access points and wireless
networking devices built by Llnksys of Irvine, California), cellular or digital
networking technologies (such as Mlcroburst® by Aeris Communications.
Inc. of San Jose, California), ultra wide band, free space optics, Global
System for Mobile Communications (GSM), Genera! Packet Radio
Service (GPRS), Code Division Multiple Access (CDMA), spread
spectrum technology, infrared communication techniques, SMS (short
messaging serviceytext messaging), or any other wireless technology.
More generally, the present invention can make use of any wireless
protocol capable of supporting data transmissions, including
transmissions over any circuit switched network or any packetized routing
network.
Again, the power supply circuit 18 is shown in phantom to
illustrate that the power supply circuit 18 may be contained within the field
device 14 or may be separate from the field device 14. The power supply
16 (shown in FIG. 1) for the control system 12 may be a plant-wide power
bus, a standard power circuit, or any other type of power supply. As
shown, the field device 14 is powered independently from the control
system 12, and wireless data transmissions between the field device 14
and the control system 12 do not impact the power supply scheme.
The power supply circuit 18 of the field device 14 may be a
wall-plug with a transformer for stepping down and filtering power from a
standard electrical socket. Alternatively, the power supply circuit 18 of
the field device 14 may be a filtering circuit connected to a plant-wide
power bus, or a rechargeable battery connected with a solar device, or
any other power supply. In general, the power supply circuit 18 refers to
any circuitry required to deliver an appropriate voltage and/or current level
to a field device 14 for operation.
It is important to understand that traditional process control
networks employ hornerun cabling to connect a control center with
distributed field devices. Typically, the hornerun cabling extends from the

control center to a junction box, which in turn connects directly to the field
devices. Communications between the field devices and the control
center traverse a path from the control center, through the junction box
and on to the field device, and information from the field device is
transmitted over the same path in reverse.
FIG. 3 illustrates an embodiment of the process control
system 10 according to the present invention, which Is made possible by
the wireless transmission capabilities. In particular, the process control
system 10 has a control system 12, which does not by itself have wireless
capability. However, the control system 12 is coupled with a wireless
transceiver 24. which may have its own power supply 26 (Internal or
external to the wireless transceiver 24). The wireless transceiver 24
adapts the control system 12 to send and receive information wirelessly.
Thus, with minimal additional equipment, the control system 12 is capable
of issuing and receiving signals wirelessly.
The process control system 10 also has one or more
junction boxes 28 connected with several field devices 30 and with a
power supply 34 and/or a power supply circuit 16. In this instance, unlike
field devices 14 (in FIGS. 1 and 2) which are provided with their own
wireless capabilities, the field devices 30 cannot directly transmit and
receive information wirelessly. However, the junction boxes 28 can be
adapted to provide shared wireless transceivers, such that data can be
transmitted over wires from the field device 30 to the junction box 28 and
then wirelessly from the Junction box 28 to the wireless transceiver 24 and
then to the control system 12.
With respect to power delivery, in this embodiment, the
junction boxes 28 deliver power to each field device 30. The junction box
28 can be provided with an external power supply 34 and/or with a power
supply circuit 16 for regulating power to the field devices 30. Additionally,
the junction box 28 may draw power from a plant-wide power bus 32, or
from any other power source, including an electrical outlet

By adapting existing networks to send and receive
information wirelessly, a number of advantages are obtained over
traditional wired network topologies. First, additional wired field devices
30 and wireless field devices 14 (Figure 2) can be added without the cost
of additional homerun cabling.
Additionally, "smart devices" (for example, field devices 14
or 30 capable of transmitting diagnostic information, device failure
information, and the like, to the control system 12) can be added to the
process control network 10, without requiring changes to the control
system 12. In particular, while it is possible to add smart devices to a
traditional process control network, a traditional control system may not
pay attention or be capable of making use of the transmitted diagnostic
information. The adaptation of the control system 12 to send and receive
wireless information via the wireless transceiver 24 ensures that the
diagnostic information reaches the control system 12 without being
filtered out. Additionally, if the control system 12 cannot make use of the
information transmitted by the smart device, the data need not be lost as
it can be received at the wireless transceiver 24 and then
programmatically diverted to a computer within the control room that can
make use of the diagnostic information. In this way, a control system can
be adapted to become a control and monitoring system, with minimal
investment In equipment and software.
Finally, since Information is transmitted wirelessly between
the field devices 30 and the control system 12 via the wireless transceiver
24, the requirements for power regulation are minimized, allowing for
cheaper power supplies. As previously discussed, conventional process
control networks required tight control over the power supply because the
same cable often carried both the power and the signals. Since
communications and power are run across the same wire, the power
regulation at the device is complicated, and therefore expensive.
Typically, special power conditioners and/or terminators had to be
installed to allow such signaling. Moreover, the cabling was expensive

because it had to be shielded cabling, because it had to be balanced with
a selected impedance, and so on. Simple low-pass filters cannot be used
because a "notch" at the communications frequency must be allowed to
pass. Additionally, conventional field devices do not include power
regulation circuitry or signal filtering circuitry that is sophisticated enough
to handle signal transmissions over a wire carrying an unregulated
voltage.
With the present invention, the plant-wide power bus 32 can
be a loosely regulated power line, without concern for the field devices
30, because the localized power supplies 34 or power circuits 16 can
perform the necessary filtering. Thus, the plant-wide power bus 32 can
be a single wire bearing a voltage potential. For example, the plant-wide
power bus 32 can deliver a twenty-four or forty-eight volt alternating
current (AC) or direct current (DC).
Alternatively, the various devices can be powered from
existing power circuity in the walls through standard electrical outlets,
which may be a 120 or 240 V AC circuit, such as the circuits that provide
power to plugs and switches within offices. In industrial settings, such
power circuits may be 480 V, and in countries outside of America, other
voltage amplitudes may be employed.
As previously discussed, it Is also possible to power field
devices 30,14 from batteries or solar power, depending on the specific
signaling requirements. For example, it may be inefficient to use batteries
in an environment where the device 30,14 must signal frequently,
because the batteries would wear out quickly, requiring frequent
replacement However, if the batteries are rechargeable and are used in
an environment where they can recharge themselves (via solar panels) or
where they are infrequently used, then such power sources can also be
utilized.
In essence, the junction box 28 allows for clusters of
wireless field devices 14 or wired field device 30 to be added to a process
control network 10 without the need for additional homerun cabling. Such

clusters of field devices can be powered by a simple local power grid or
via individual power sources. Since plants typically have AC power run
throughout the facilities, similar to a house, a cheap power supply could
be used to provide the DC power to a cluster of transmitters simply by
tapping into the existing AC power and stepping down the voltage.
FIG. 4 Illustrates an alternative embodiment of the present
invention wherein the field device 30 Is provided with its own power
supply 18. In this embodiment, the junction box 28 and the control
system 12 are both powered from the plant-wide power bus 32. The
control system 12 fs adapted for wireless transmissions via a wireless
transceiver 24. Additionally, the junction box 28 is provided with a shared
wireless transceiver 36 (shown in phantom) to adapt the duster of wired
field devices 30 for wireless transmissions.
!n this way, the individual power supplies and wiring for the
junction box 28 (not shown) and the power supplies 18 for the field
devices 30 can be made very cheaply, to provide the appropriate level of
power to each of the various components without concern for signal
filtering. Once again, since wireless transmissions are used to
communicate between the field devices 30 and the control system 12, the
power supply means can be essentially "ad hoc", meaning as needed to
fit the particular circumstance and without consideration of wider
application
Thus, by divorcing power delivery from signaling, field
devices 30,14 can be inserted into an existing network by tapping into an
existing power circuit, such as a standard AC power circuit (e.g. via a wall
outlet). The power supply 18 may be simply a standard plug with a
transformer. Alternatively, the power supply 18 may be a rechargeable
battery connected with a solar panel or other environmentally sustainable
power source. In another embodiment, the power supply 18 may be a
rechargeable battery connected to a standard wail socket or an
uninterruptable power supply (UPS), similar to (but smaller than) such
devices designed for power failover in networks and the like.

More importantly, since the voltage supply does not need to
be as tightly regulated, simple low-pass or other types of filters can be
used to provide power regulation at the field devices 18 or in the junction
box 28. In this way, the overall cost of installation and expansion of a
process control network 10 is reduced, in part, because additional field
devices 14,30 and junction boxes 28 can be added to the network 10
without expensive homerun cabling 14.
In general, by divorcing the signaling path from the power
supply and by providing a variety of means for delivering power to the
field devices 14 and 30, the process control network 10 can be configured
in multiple ways, using network topologies and configurations that might
not otherwise be feasible. Specifically, additional field devices 14 and 30
(together with shared wireless transceivers 36 as needed) can be added
to the process control network 10 as needed, and without concern for the
geographic proximity of the individual wireless field devices 14 or of the
adapted field devices 30 to the existing network wiring. Using standard
and inexpensive power supplies coupled with existing power circuitry,
field devices 30 (with a shared wireless transceiver 36) and field devices
14 (with built-in wireless communications boards 22) can communicate
wirelessly with the control system 12, regardless of their physical location
relative to the control system 12.
The present invention introduces several advantages over
traditional control networks. First, by divorcing the power supply and ths
signaling path, the present Invention allows for inexpensive expansion of
existing networks because once the control system 12 is adapted for
wireless transmissions, new field devices 14 can be added as needed
without requiring additional wiring. Additionally, by relying on existing
power networks to power individual field devices 14 or groups of field
devices 14 or 30, the number of field devices 14,30 In the network is not
limited by cabling, allowing for easy expansion of existing networks 10.
Furthermore, since the field devices 14,30 no longer derive their power
and signals from the same path, communication may be dramatically

and/or dynamically altered. Specifically, in certain circumstances, it may
be desirable for the field devices 14,30 or rather their communications
with the control system 12 to be self-organizing.
FIG. 5 illustrates a hybrid network containing a self-
organizing wireless communication component and the wireless ,
communication discussed with respect to FIGS. 1-4. As shown, the
control system 12 is adapted to transmit and receive information
wirelessly via a wireless transceiver 24. The control system 12 is
powered by a plant-wide power bus 32, which may be a single voltage
carrying wire, an existing power circuit, or any other power delivery
mechanism. Depending on what type of power delivery mechanism the
plant-wide power bus 32 is. the control system 12 and the Junction box 28
may be provided as required with power filtering circuitry (not shown).
As shown, a junction box 28 is adapted to provide wireless
communications between wired field devices 30 and the control system
12 via a shared wireless transceiver 36. The junction box 28 draws
power from the same plant-wide power bus 32 as the control system 12.
Finally, in this embodiment, a self-organizing portion of the
control network 10 includes a junction box 38 provided with a wireless
transceiver 40A and a wireless transceiver 40B. The junction box 38 is
powered with Its own power supply 26. Two field devices 14 in
communication with each other and with the wireless transceiver 40B of
the junction box 38 are shown. Each field device 14 is provided with its
own power supply 18.
In this embodiment, the field devices 14 include a wireless
transceiver and a transducer/actuator (not shown). The wireless
transceiver of the field devices 14 (in this instance) may be short range or
802.11 (b) type communications (or any other type of wireless
communications). The field devices 14 can relay messages from another
field device 14 or communicate directly with the junction box 38 and its
wireless transceiver 40B. The junction box 38 relays information between
the control center 12 and the field devices 14. Specifically, information

sent by the field devices 14 is received by the wireless transceiver 40B,
which passes the information to wireless transceiver 40A for transmission
to the control center 12 via wireless transceiver 24. Signals sent from the
control center 12 follow the same path in reverse. If, for some reason, a
field device 14 is unable to transmit directly to the Junction box 38, the
field device 14 can simply find a different path, by transmitting the data to
the junction box 38 via another field device 14.
As shown, the type of signal between the field devices 14
and the junction box 38 are different than those between the junction box
38 and the control system 12, indicating a different type of transceiver
card. However, the entire control network 10 can be implemented as a
self organizing network, such that data could travel back and forth across
the network by wirelessly relaying the information. Essentially, the field
devices 14 can be implemented to form a loose-knit, variable, process
control network 10, which can adapt to transmit and receive information
between field devices 14 and the control system 12 via any available data
path. This type of network may utilize 802.11(b)-type, short-range
wireless communications, infrared, or any type of wireless
communications.
With a self-organizing process control network 10, newly
added field devices 14 simply see the wireless signal and begin
communicating. If, for some reason, a field device 26 goes off-line,
transmissions can be instantly adapted over a different signal path via the
self-organizing network. As shown, the signals may take different paths
as needed. Moreover, new communication paths may be made or
broken as needed to facilitate communications between the control
system 12 and the individual field devices 14.
The advantages of the self-organizing network architecture
are numerous, though one foreseeable downside is the fact that a
significant portion of a plant may need to be "set up" for this architecture
to work. As wireless connectivity becomes cheaper and easier to use,
existing systems can be adapted easily and cost effectively. Also, if the

communication protocol that is selected is a standard communications
protocol (such as IEEE 802.15.4 and the like), connection to the host is
made very simple. The cost advantages of this architecture are so large
and the prices of wireless components are so cheap that the adaptation
of a traditional host system can be very low cost.
An additional advantage of this system 10 is that current
power supplies used to power wireless sensors or field devices 14 would
be eliminated, thereby reducing environmental implications of spent
power sources such as batteries- By powering the field devices 14 from
an existing power circuit, no new infrastructure wiring is required and no
new power source waste is generated. Moreover, cost savings in wiring
alone can be significant, particularly in large plants or in control processes
where the process changes dramatically.
FIG. 6 shows a process control network 10 with a control
system 12 adapted for wireless communications via a wireless
transceiver 24. A junction box 28 is provided with a shared wireless
transceiver 36 for field devices 30. Both the control system 12 and the
junction box 28A are powered from the same plant-wide power bus 32. A
second junction box 28B is provided with a separate power supply 26 and
a power supply circuit 42, for delivering power from the power supply 26
to the wireless field devices 14. As shown, the field devices 14 are
individually grounded (ground 46), allowing the power to be delivered via
a single wire 44 to ons or more field devices 14.
As previously discussed, by divorcing the communication
path from the power supply, the process control network 10 need no
longer be defined by the wiring (or by the homerun cabling). By utilizing
wireless communications, existing process control networks can be
adapted and new process control and monitoring networks can be
constructed, changed, and extended as needed and without expensive
rewiring. In particular, wireless field devices 14 can be plugged in and
added to an existing network on the fly, wired devices 30 can be adapted
to provide wireless communications via a shared wireless transceiver 36,

smart devices can be inserted, and each can be powered according io
available power circuits. If a wall socket is nearby, the device can be
plugged into the wall socket. Alternatively, a single voltage carrying wire
(as opposed to more expensive homerun cabling) can be run throughout
the facility, and power filtering can then be performed at the individual
field devices 14, 30 or at the junction box in order to deliver the necessary
power.
Although the present invention has been described with
reference to preferred embodiments, workers skilled in the art will
recognize that changes may be made in form and detail without departing
from the spirit and scope of the invention.

WE CLAIM
1. A distributed control and/or monitoring system (10) within an industrial
plant, the system (10) comprising:
a control/monitoring center (12);
a plurality of field devices (14) within the industrial plant having no
hardwired communication link to the control/monitoring center (12) and
each other, each field device (14) comprising:
a transducer (20);
a wireless transceiver (22) for communicating wirelessly; and
a plant-wide power bus (32) for delivering power to each field device (14),
wherein the power bus (32) does not include and is separate from any
communication signal path between the control/monitoring center (12)
and the field devices (14).
2. The distributed system (10) as claimed in claim 1, wherein each field
device comprises:

a power circuit (18) for controlling power delivery from the power bus
(32) to the transducer (20) and to the wireless transceiver (22) within the
field device (14).
3. The distributed system (10) as claimed in claim 1 wherein the plant-wide
power bus (32) is a single wire bearing a voltage.
4. The distributed system (10) as claimed in claim 1 wherein each of the
plurality of field devices (14) communicates wirelessly with the
control/monitoring center (12).
5. The distributed system (10) as claimed in claim 1 wherein some of the
plurality of field devices (14) are positioned within close proximity to one
another in a cluster, the system comprising:
a power circuit (16) connected to the plant-wide power bus (32) for
controlling power supplied to the cluster of field devices (14).
6. The distributed system (10) as claimed in claim 5 wherein the power
circuit (16) comprises:
a ground loop connected to earth ground for electrically grounding each
of the field devices (14) in the cluster of field devices (14).
7. The distributed system (10) as claimed in claim 5 wherein each field
device (14) is individually grounded to earth.

8. A distributed system (10) for monitoring an industrial process within an
industrial plant, the system comprising:
a control/monitoring center (12);
a plurality of field devices (14) for sensing or altering the industrial
process, each field device (14) having a transducer (20) and a wireless
transceiver (22) for communicating signals between the field device (14)
and the control/monitoring center (12); and
a plant-wide power bus (32) comprising a wire carrying an unfiltered
voltage potential for delivering a voltage potential to each of the plurality
of field devices (14), wherein the power bus (32) does not include and is
separate from any communication signal path between the
control/monitoring center (12) and the field devices (14).
9. The distributed system (10) as claimed in claim 8, wherein each of the
plurality of field devices (14) comprises:
a voltage regulator (16) for controlling power delivered from the plant-
wide power bus (32) to the wireless transceiver (22).
10.The distributed system (10) as claimed in claim 9, wherein each of the
plurality of field devices (14) comprises:

a direct connection to a ground.
11.The distributed system (10) as claimed in claim 8, wherein two or more of
the plurality of field devices (14), which are in close proximity to one
another, constitute a group, and comprising:
a power supply (34) for stepping down an existing alternating or direct
current voltage from the plant-wide power bus (32) to a lower voltage,
wherein a single wire is connected from each field device (14) to the
power supply (34).
12.The distributed system (10) as claimed in claim 8, wherein at least one
field device (14) comprises: a power regulation circuit (16) for stepping
down an existing alternating or direct current voltage from the plant-wide
power bus (32) to the voltage potential for delivery to the field device
(14).
13.The distributed system (10) as claimed in claim 8 wherein the voltage
potential is less than five volts.
14.The distributed system (10) as claimed in claim 8, wherein the plant-wide
power bus (32) is a standard AC or DC circuit.
15.A method for retrofitting an existing field device network in an industrial
plant for wireless communications, the method comprising:

installing a first wireless transceiver (24) in communication with a
control/monitoring center (12);
installing a second wireless transceiver (36) on an existing plant-wide
power bus and in communication with one or more field devices (30); and
configuring the second wireless transceiver (36) to communicate with the
one or more field devices (30) and to transmit data wirelessly from the
one or more field devices (30) to the control/monitoring center (12) in
addition to data transmitted over an existing communication link;
wherein the power bus (32) does not include and is separate from any
communication signal path between the control/monitoring center (12)
and the field devices (30).
16.The method as claimed in claim 15, comprising:
installing a "smart" field device on the fieldbus network, the "smart" field
device having a wireless transceiver (22), the "smart" field device for
providing diagnostic information to the control center (12).
17.A distributed field device system (10) comprising:
a single-wire plant-wide power bus (32); and

a plurality of wireless field devices (14), each wireless field device (14)
comprising:
a transducer (20);
a wireless transceiver (22) for sending information from the transducer
(20) to a control center (12); and
power circuitry (18) for drawing adequate power from the single-wire
plant- wide power bus (32) to power the transducer (20) and the wireless
transceiver (22);
wherein the power bus (32) does not include and is separate from any
communication signal path to or from the field devices (14).
18. A field device (14) for use in an industrial plant having a plant-wide power
bus (32), the field device (14) comprising:
a transducer (20);
a wireless transceiver (22);
a power terminal for connecting the field device (14) to the plant-wide
power bus (32);
a ground connection for electrically grounding the field device (14); and

an internal power supply circuit (18) connected to the power terminal and
the ground connection for supplying power to the transducer (20) and the
wireless transceiver (22);
wherein the power bus (32) does not include and is separate from any
communication signal path to or from the field devices (14).
19.The field device as claimed in claim 18, wherein the plant-wide power bus
(32) is a single wire carrying a voltage potential other than zero, and the
power terminal is connectable to the single wire.


The invention relates to a process control system (10)
utilises wireless transceivers to divorce the field devices
(14,30) from traditional wired network topologies. By providing
field devices (14, 30) with wireless transceivers (22) and shared
wireless transceivers (36) for adapting wired field devices (30),
the field device network may be adapted to any number of network
topologies without concern for additional wiring costs.
Specifically, a power supply (18, 26) can be provided for each
field device (14) or for groups of field devices, as needed.
Thus, the entire network can receive power from a single power
bus (32), without expensive power filtering. In addition, the
network can be a bybrid in which part of the information is
transmitted and received over wired lines and part is transmitted
and received over wireless communication.

Documents:

01900-kolnp-2006 abstract.pdf

01900-kolnp-2006 claims.pdf

01900-kolnp-2006 correspondence others.pdf

01900-kolnp-2006 description(complete).pdf

01900-kolnp-2006 drawings.pdf

01900-kolnp-2006 form-1.pdf

01900-kolnp-2006 form-2.pdf

01900-kolnp-2006 form-3.pdf

01900-kolnp-2006 form-5.pdf

01900-kolnp-2006 international publication.pdf

01900-kolnp-2006 pct form.pdf

01900-kolnp-2006 priority document.pdf

01900-kolnp-2006-correspondence-1.1.pdf

01900-kolnp-2006-form-18.pdf

1900-KOLNP-2006-(20-06-2012)-CORRESPONDENCE.pdf

1900-KOLNP-2006-(20-06-2012)-PA.pdf

1900-kolnp-2006-amanded claims.pdf

1900-KOLNP-2006-ASSIGNMENT.pdf

1900-KOLNP-2006-CORRESPONDENCE.pdf

1900-kolnp-2006-examination report reply recieved.pdf

1900-KOLNP-2006-EXAMINATION REPORT.pdf

1900-KOLNP-2006-FORM 13.pdf

1900-KOLNP-2006-FORM 18.pdf

1900-KOLNP-2006-FORM 26.pdf

1900-KOLNP-2006-FORM 3.pdf

1900-KOLNP-2006-FORM 5.pdf

1900-KOLNP-2006-GRANTED-ABSTRACT.pdf

1900-KOLNP-2006-GRANTED-CLAIMS.pdf

1900-KOLNP-2006-GRANTED-DESCRIPTION (COMPLETE).pdf

1900-KOLNP-2006-GRANTED-DRAWINGS.pdf

1900-KOLNP-2006-GRANTED-FORM 1.pdf

1900-KOLNP-2006-GRANTED-FORM 2.pdf

1900-KOLNP-2006-GRANTED-SPECIFICATION.pdf

1900-KOLNP-2006-OTHERS.pdf

1900-KOLNP-2006-REPLY TO EXAMINATION REPORT 1.1.pdf

abstract-01900-kolnp-2006.jpg


Patent Number 253065
Indian Patent Application Number 1900/KOLNP/2006
PG Journal Number 25/2012
Publication Date 22-Jun-2012
Grant Date 21-Jun-2012
Date of Filing 07-Jul-2006
Name of Patentee ROSEMOUNT, INC.
Applicant Address 12001 TECHNOLOGY DRIVE, EDEN PRAIRIE, MN 55344-3695
Inventors:
# Inventor's Name Inventor's Address
1 KARSCHNIA, ROBERT, J C/O. ROSEMOUNT, INC., 12001 TECHNOLOGY DRIVE EDEN PRAIRIE, MINNESOTA 55344-3695
2 ROMO, MARK, G C/O. ROSEMOUNT, INC., 12001 TECHNOLOGY DRIVE EDEN PRAIRIE, MINNESOTA 55344-3695
3 PELUSO, MARCOS C/O. ROSEMOUNT, INC., 12001 TECHNOLOGY DRIVE EDEN PRAIRIE, MINNESOTA 55344-3695
PCT International Classification Number H04Q 7/20
PCT International Application Number PCT/US2004/038531
PCT International Filing date 2004-11-12
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 10/734,889 2003-12-12 U.S.A.