Method of locating a field device using a handheld field maintenance tool

BACKGROUND

0001Handheld field maintenance tools are known. Such tools are highly useful in the process control and measurement industry to allow operators to conveniently communicate with and/or interrogate field devices in a given process installation. Examples of such process installations include petroleum, pharmaceutical, chemical, pulp, and other fluid processing installations. In such installations, the process control and measurement network may include tens or even hundreds of various field devices which periodically require maintenance to ensure that such devices are functioning properly and/or calibrated. Moreover, when one or more errors in the process control and measurement installation are detected, the use of a handheld field maintenance tool allows a technician to quickly diagnose such errors in the field. Handheld field maintenance tools are generally used to configure, calibrate, and diagnose problems relative to intelligent field devices using digital process communication protocols.

0002Since at least some process installations may involve highly volatile, or even explosive, environments, it is often beneficial, or even required, for field devices and the handheld field maintenance tools used with such field devices to comply with intrinsic safety requirements. These requirements help ensure that compliant electrical devices will not generate a source of ignition even under fault conditions. One example of Intrinsic Safety requirements is set forth in: <nplcit id="ncit0001" npl-type="b"><text>APPROVAL STANDARD INTRINSICALLY SAFE APPARATUS AND ASSOCIATED APPARATUS FOR USE IN CLASS I, II and III, DIVISION NUMBER 1 HAZARDOUS (CLASSIFIED) LOCATIONS, CLASS NUMBER 3610, promulgated by Factory Mutual Research October, 1998</text></nplcit>. An example of a handheld field maintenance tool that complies with intrinsic safety requirements includes that sold under trade designation Model 475 Field Communicator, available from Emerson Process Management of Austin, Texas.

0003<patcit id="pcit0001" dnum="EP2071427A"><text>EP 2 071 427</text></patcit> is considered to be the closest prior art and discloses a field device search system which is composed of a plurality of field devices having a wireless transmitting/ receiving capability and an information terminal having a receiving capability to receive radio waves from a field device, wherein the information terminal includes a radio wave receiver, a CPU (arithmetic means), a display part, a memory, and member for identifying one of the plurality of field devices.

SUMMARY

0004A method of locating a field device using a handheld field maintenance tool is described according to independent claim 1.

BRIEF DESCRIPTION OF THE DRAWINGS

0005<ul id="ul0001" list-style="none" compact="compact"><li><figref idref="f0001">FIGS. 1A and 1B</figref> are diagrammatic views of a handheld field maintenance tool with which embodiments of the invention are particularly useful.</li><li><figref idref="f0002">FIG. 2</figref> is a diagrammatic view of a handheld field maintenance tool with which embodiments of the present invention are particularly useful.</li><li><figref idref="f0003">Fig. 3</figref> is a block diagram of a handheld field maintenance tool in accordance with an embodiment of the present invention.</li><li><figref idref="f0004">FIG. 4</figref> is a flow diagram of a method of locating a field device in accordance with an embodiment of the present invention.</li><li><figref idref="f0005">FIG. 5</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention, but which is not part of the present invention.</li><li><figref idref="f0006">FIG. 6</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention, but which is not part of the present invention.</li><li><figref idref="f0007">FIG. 7</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention, but which is not part of the present invention.</li></ul>

DETAILED DESCRIPTION

0006<figref idref="f0001">FIGS. 1A and 1B</figref> are diagrammatic views of a handheld field maintenance tool 22 coupled to field devices 20, 23. As shown in <figref idref="f0001">FIG. 1A</figref>, handheld field maintenance tool 22 includes a pair of terminals 25, 27 that couple to test leads 30, 32, respectively, which are then coupled to terminals 24 of field device 20. Terminals 24 may be dedicated terminals to allow such a handheld field maintenance tool to couple to device 20 and interact with device 20. The utilization of terminals 25, 27 to couple to field device illustrates an example of a wired connection between handheld field maintenance tool 22 and field device 20.

0007<figref idref="f0001">FIG. 1B</figref> shows an alternate arrangement where handheld field maintenance tool 22 couples directly to the process control loop 34 to which field device 23 is coupled. In either case, the wired connection between the handheld field maintenance tool and the field device allows the handheld field maintenance tool to interact with the desired field device 20, 23. As will be described in greater detail below, embodiments of the present invention are useful for locating any process installation assets or objects, including, but not limited to, field devices.

0008<figref idref="f0002">FIG. 2</figref> is a diagrammatic view of handheld field maintenance tool 102 interacting with wireless field device 104. System 100 includes handheld field maintenance tool 102 communicating with field device 104. Handheld field maintenance tool 102 is communicatively coupled to field device 104 via communication link 114. Communication link 114 can take any suitable form including wired connections as shown in <figref idref="f0001">FIGS. 1A and 1B</figref>, as well as wireless communication techniques that are currently being used or being developed. Handheld field maintenance tool 102 allows a technician to interact with field device 104 to configure, calibrate, and/or diagnose problems with respect to field device 104 using a digital process communication protocol such as FOUNDATION™ Fieldbus and/or the HART® protocol. Handheld field maintenance tools, such as tool 102 can be used to save configuration data from field devices, such as field device 104. Embodiments of the present invention are also useful for communicating on a process installation bus where a number of field devices (such as 16+) communicate and differentiating one field device from others.

0009Field device 104 may be any device that senses a variable in the process and transmits information related to the variable over a process communication loop; such as a pressure or temperature. Field device 104 may also be a device that receives information from a process communication loop and sets a physical parameter, such as a valve closure, based on the information. Field device 104 is depicted as an industrial process fluid pressure transmitter having a pressure manifold 106 coupled thereto, and an electronics enclosure 108. Field device 104 is provided for illustrative purposes only. In reality, field device 104 may be any industrial device, such as a process fluid temperature transmitter, process fluid level transmitter, process fluid flow transmitter, valve controller, or any other device that is useful in the measurement and/or control of industrial processes.

0010Handheld field maintenance tool 102 generally includes a user interface that comprises a display 120 as well as a number of user input buttons 122. Display 120 may be any suitable display such as an active-matrix liquid crystal display, or any other suitable display that is able to provide useful information. Buttons 122 may comprise any suitable arrangement of buttons relative to any number of functions to which the handheld field maintenance tool may be directed. Buttons 122 may comprise a numeric keypad, an alphanumeric keypad, any suitable number of custom functions and/or navigation buttons, or any combination thereof.

0011<figref idref="f0003">Fig. 3</figref> is a diagrammatic system block diagram of a handheld field maintenance tool in accordance with the embodiment of the present invention. It is preferred that tool 52 comply with at least one intrinsic safety specification, such as that listed above, in order to help ensure safety in potentially explosive environments. Handheld field maintenance tool 52 includes at least one wireless process communication module 121. Suitable examples for wireless process communication module 121 include a module that generates and/or receives proper signals in accordance with a known wireless communication protocol, such as the known WirelessHART protocol (IEC 62591). Another wireless process communication protocol is set forth in ISA100.11a. While <figref idref="f0003">Fig. 3</figref> shows a single wireless process communication module 121, it is expressly contemplated that any suitable number of wireless process communication modules can be used to communicate in accordance with various wireless process communication protocols now in existence or later developed. While embodiments of the present invention are generally described with respect to an intrinsically-safe handheld field maintenance tool that includes at least one process communication module, some embodiments may be practiced without process communication, using only GPS position information and a handheld tool.

0012Handheld field maintenance tool 52 also includes at least one secondary wireless communication protocol module 123. Wireless communication protocol module 123 can communicate in accordance with one or more of the options shown in phantom in <figref idref="f0003">Fig. 3</figref>. Specifically, wireless communication protocol module 123 may communicate in accordance with a Bluetooth specification 124 (such as Bluetooth Specification 2.1 rated at Power Class 2; a Wi-Fi specification 126 (such as IEEE 802.11.a/b/g/n); a known RFID specification 128; cellular communication techniques 130 (such as GSM/CDMA); and/or satellite communication 132. These communication techniques and methodologies allow handheld field maintenance tool 52 to communicate directly with a wireless gateway or other suitable device either via direct wireless communication, or using the Internet. While one wireless communication protocol module 123 is shown in <figref idref="f0003">Fig. 3</figref>, any suitable number may be used. Each of the wireless process communication protocol module 121 and wireless communication protocol module 123 is coupled to controller 130 which is also coupled to the wired process communication module 138. Controller 130 is preferably a microprocessor that executes a sequence of instructions stored therein, or in memory coupled to controller 130, to perform handheld field maintenance tasks. Wired process communication module 138 allows handheld field maintenance tool 52 to be physically coupled via a wired connection at terminals 142, 144 to a field device. Examples of suitable wired process communication include the highway addressable remote transducer (HART®) protocol, the FOUNDATION™ Fieldbus protocol, Profibus and others.

0013Handheld field maintenance tool 52 includes a user interface module 156 for generating a user interface using display 120 and keys 122. Module 156 can include suitable display driver circuitry 158 and/or memory to interact with display 120. Module 156 also includes input circuitry 160 which is configured to interact with buttons 122 to receive user input. Additionally, in embodiments where display 120 includes a touchscreen, module 160 can include circuitry to generate user input data to controller 130 based upon a user's touch and/or gestures received by the touchscreen.

0014Handheld field maintenance tool 52 can include a number of additional items that facilitate additional functionality. Specifically, tool 52 can include a position detection module, such as GPS module 150. GPS module 150 can be configured to additionally use the Wide Area Augmentation System (WAAS) for improved accuracy and/or can be configured to operate using differential GPS techniques as appropriate. Module 150 is coupled to controller 130 to provide controller 130 with an indication of the geographic position of tool 52. While position detection module 150 is preferably an internal component of tool 52, it may be external and communicatively coupled thereto using a suitable wireless or wired communication protocol, such as Bluetooth 124, RFID 128, et cetera. Further still, while position detection module 150 is generally described as GPS module 150, other techniques for triangulating the position of the handheld field maintenance tool based upon relative strength of wireless communication with wireless transceivers having known fixed positions can be employed. Examples of such wireless triangulation techniques include triangulation of the position of handheld field maintenance tool 52 based upon communication with three or more fixed-position WiFi communication points, or access points. Further still, as set forth above, embodiments of the present invention may include the ability to employ one or more wireless process communication protocol modules, such as module 121. Such triangulation techniques can also be employed if a suitable number of wireless interactions with fixed-position wireless field devices can be achieved. Finally, while the various methods provided for obtaining the position of handheld field maintenance tool 52 are described above, they can also be used in conjunction with one another to provide additional accuracy and/or redundancy. Additionally, tool 52 also preferably comprises compass module 152 coupled to controller 130 such that tool 52 can indicate the compass direction in which it is pointing. Finally, tool 52 can also include tilt module 154 coupled to controller 130 to provide an indication to controller 130 relative to an angle of inclination of tool 52 relative to gravity. However, additional axes of sensing are also contemplated.

0015The positional location module 150, compass module 152 and tilt module 154 are particularly useful where a handheld field maintenance tool helps a technician or engineer find the physical location of a wireless field device in the field. An oil refinery is often a very large process installation with many field devices positioned at various locations, some of which may not be readily visible. When a technician or engineer needs to physically locate a field device to perform engineering, setup and/or maintenance tasks, the technician or engineer would previously need to perform one of the following tasks. The technician or engineer would be forced to search for the field device based on memory or word-of-mouth directions from another technician or engineer. Alternatively, the technician or engineer would look up the field device in engineering drawings, which often do not contain detailed information about the physical location of the device. Then, based on that often limited information, the technician or engineer would attempt to physically locate the device in the plant or process installation.

0016Embodiments of the present invention generally utilize geographical information relative to a fixed-position field device, which information is loaded into, or otherwise created within a handheld field maintenance tool to allow the handheld field maintenance tool to help a user to navigate to the physical location of the field device. Moreover, in some embodiments, such location information may be transferred from one handheld field maintenance device to another such that another technician's handheld field maintenance tool can be updated with location information from a first technician's handheld field maintenance tool in order for both technicians to have the ability to quickly and easily find the navigate to the physical position of the field device. Preferably, this transfer of information between handheld field maintenance tools is performed wirelessly; however any suitable technique for transferring information between the handheld field maintenance tools can be employed.

0017As illustrated in <figref idref="f0003">FIG. 3</figref>, handheld field maintenance tool 52 preferably includes camera 157. Camera 157 is preferably disposed within handheld field maintenance tool 52, and is configured to acquire still and/or video images. Further, camera 157 can also be provided with an audio input such that real-time video recording with sound can be provided.

0018Embodiments of the present invention generally leverage the handheld field maintenance tool's ability to determine its own position in order to facilitate position-based field maintenance. Preferably, handheld field maintenance tool 52 uses GPS and/or cellular or WirelessHART triangulation to help a technician navigate to the position of a field device or process asset within a reasonable radius. The utilization of wireless signal triangulation (in additional to simply using GPS) is important since the industrial process environment generally interferes with traditional GPS signals/receivers. Thus, a position location module that is configured to use triangulation in place of or in combination with GPS is advantageous in a process installation. Further still, WirelessHART triangulation is specifically preferred due to the availability of multiple reference points (such as a number of fixed-positional wireless field devices) in close proximity to the asset.

0019According to an aspect which is not part of the present invention, in order to facilitate location-based field maintenance, each field device generally has its physical location assigned or otherwise determined when it is commissioned, or interacted with by a technician. One way in which a field maintenance technician can set the location of a device is for the handheld field maintenance technician to run or otherwise execute a software application stored in memory within controller 130, which application renders a map on display 120. The map will show the location of the handheld field maintenance tool as determined by position module 150. The technician can then move to a position as close to the field device as possible without losing the accuracy of the position detection signal (GPS/cellular/WirelessHART/WiFi) and then drag, or otherwise interact with, an icon representing the field device onto the map. If an entry for the field device does not already exist in a local database of the handheld field maintenance tool, an entry is created. The technician then moves the field device icon on the map in any direction and for any distance relative to the handheld field maintenance tool's current position until the technician is satisfied that the indicated position on the mini-map is a reasonable representation of the physical reality. Alternatively, the technician can simply move the handheld field maintenance tool to the position of the field device. Next, the technician selects the icon and sets the location within the handheld field maintenance tool. This stores the positional information representative of the handheld field maintenance tool's current position as modified by the technician's icon-based movement vector, if any.

0020The map rendered on display 120 can be any suitable pictorial representation of the position of the handheld field maintenance tool relative to a field device. The map is preferably two-dimensional, but may be three-dimensional. Additionally, the technician can also assign an altitude of the field device through data entry. The coordinate provided for altitude can be either positive (height above ground) or negative (depth below ground). The altitude parameter is used to cause the map icons to appear slightly different (such as transparent) even when the handheld field maintenance tool is at the same exact location as the field device to indicate to the technician that the field device is not at ground level. Preferably, the transparency varies with the distance from ground level. For example, the farther the field device is from the ground level, the more transparent the associated field device icon. Additionally or alternatively, the height parameter or altitude itself can be indicated next to or on the field device icon. Further still, any other suitable pictorial indication relative to the field device can be provided to indicate the height parameter. For example, the color of the field device icon can be varied from a first color, indicating depths below ground, to a second color indicating heights above ground. For non-communicating process assets, such as a large tank, the icon, or other suitable representation thereof, preferably indicates non-communication by virtue of an icon property. For example, a red icon may indicate a non-communicating process installation asset.

0021According to an aspect which is not part of the present invention, when the technician applies the field device location to the map, the handheld field maintenance tool may communicate with the field device through wired process communication module 138, or wireless process communication module 121, as may be appropriate, to assign positional coordinates (such as latitude, longitude, and altitude) to that field device. Alternatively, the handheld field maintenance tool can interact with an asset management system to update, or otherwise store, the positional information of the field device. Additionally, field devices that do not employ digital communication (such as conventional devices employing 4-20 mA signaling) can also be located by the handheld field maintenance tool and the position of such devices can be uploaded to the asset management system. In embodiments where the handheld field maintenance tool may not have ready-access to an asset management system, the handheld field maintenance tool itself may simply store and maintain an asset tracking database that stores field device location information and subsequently synchronize with a personal computer-based asset management application.

0022While any and all field devices may be mapped, or otherwise have their physical position determined and stored, other process devices and/or fixtures may also be similarly mapped. Essentially, any device or asset in a process installation can be assigned an icon and position in this way. For instance, a large piece of equipment such as a tank can be captured as a reference point on the map. In such a scenario, the asset database within the asset management application and/or the handheld field maintenance tool is required since the tank will not necessarily communicate in accordance with a process industry communication protocol.

0023According to an aspect which is not part of the present invention, in order to further facilitate location-based field maintenance, an individual field device's connection to the rest of the process communication bus/network (for example, Spur block) can be captured and stored in the field device, or the asset database as a setup connection point coordinates. These coordinates may include the standard GPS coordinates for locating the connection hub (longitude, latitude, altitude) and a potential a fourth parameter (terminal number or terminal identification) that is used by a field technician to determine which terminal connection was used to connect/power the field device.

0024<figref idref="f0004">FIG. 4</figref> is a flow diagram of a method of locating a field device in accordance with the present invention. Method 200 begins at block 202 where a field device is selected. The selection of a field device can be in the form of the user or technician initiating a search 204 for the field device's asset tag. Additionally, if the user is using, or has access to, an application such as a DCS host 206, asset management system 208, or handheld monitoring application 210, the user or technician may be able to invoke a context-sensitive menu, such as by right clicking on a field device, to select the field device.

0025Once a particular field device is selected, positional information for the selected field device is obtained at block 212. As set forth above, this positional information may be stored locally in a handheld field maintenance tool, or stored in a database in an asset management system. Further, the positional information may even include handwritten records or notes. Regardless, the positional information obtained at block 212 is provided to a handheld field maintenance tool, and a map is generated at block 214. Preferably, the map is initially centered upon the field device indicated by the positional information. The current position of the handheld field maintenance tool is then used to render an icon or representation of the handheld field maintenance tool position relative to the selected field device. This is merely a preferred embodiment, since it is also contemplated that the handheld field maintenance tool can be the center of the map. Preferably, the map is preferably referenced to North, or referenced based upon the current heading of the handheld field maintenance tool as indicated by compass module 152. Preferably, the scale of the map is automatically selected such that the initial rendering of the map places the handheld field maintenance tool near an edge of the map with the selected field device at the center of the map, or vice versa. Additionally, a background picture is preferably used to provide scale. For example, a satellite view of the process installation can be used. However, any suitable pictorial representation of the process installation generated or obtained from blueprints or CAD drawings may be used in addition to, or in place of, a satellite view. Finally, an aerial view taken from an airplane could also be used for the background picture of the map. Preferably, the user interface provides the technician with the ability to manipulate the map by zooming in to show more detail, and zooming out to show more landmarks. Alternatively, the background picture can be a reference asset image to show the technician an example appearance of the field device for which he or she is searching.

0026Once the map is rendered, or otherwise displayed, the technician will begin to physically journey into the field to locate the selected field device or process asset. As the handheld field maintenance tool detects the change in the technician's position, the handheld field maintenance tool repeatedly tests whether the technician is within a selected proximity 216 of the field device. If the technician has not achieved a selected proximity to the field device, the map is continually updated, as indicated at block 218, and the loop continues until the technician reaches a selected proximity of the field device. Upon reaching the selected proximity of the field device, block 220 executes where close proximity location of the field device is initiated.

0027Generally locating a field device amongst a group of field devices confined to a small geographic area is difficult with simply the GPS/cellphone/WirelessHART location options. In order to further assist the technician once a selected proximity has been achieved, at least two close proximity location options are provided. The first close proximity location option is based upon RFID tags. RFID tags use near-field communication to exchange information between a tag and a reader. RFID tags are quite useful, but generally require close proximity to the RFID reader. Active RFID tags have a longer range, yet require a battery and are somewhat more expensive. As indicated in <figref idref="f0003">FIG. 3</figref>, RFID module 128 can be used to interact with RFID tags in the selected field device to achieve close proximity location. A second option for close proximity location is relative location coordinates 224. Relative location coordinates include a pair of numbers (1, 1) to (255, 255) and a description of the reference point from the perspective of someone standing South of the reference and facing North toward the reference. For instance, a wellhead (face North) may be the reference point. Once again, the map is preferably created where the visible devices are fully visible (i.e. not transparent). Devices hidden from view by the wellhead or other equipment are preferably transparent. A coordinate of (1, 1) would be the upper left hand corner of the technician's viewing area and a coordinate of (255, 255) would be the lower right hand corner of the viewing area. If a camera is installed on the handheld field maintenance tool, a picture could also be taken to show the viewing area. Once the technician has located the field device using close proximity location 220, the location is preferably verified. One way in which the located device could be verified is the presence or reference to the physical tag of the field device. In some instances, this may not be possible if the tag has become damaged or corroded to some extent. Preferably, the field device is installed with a jumper or button, or other suitable circuit that can be accessed by the field maintenance technician locally to generate a squawk message 226 to broadcast on the field device's native process communication loop or segment using the field device's native process communication protocol. The handheld maintenance tool used by the technician then listens to the process communication loop/segment for the squawk signal or message to confirm that the correct device has generated the squawk before maintenance on that device is performed by the technician.

0028<figref idref="f0005">FIG. 5</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention. Method 300 begins at block 302 where a handheld field maintenance tool is communicatively coupled to a process communication loop or segment. Next, at block 304, the handheld field maintenance tool communicates over the process communication loop or segment to identify all field devices on the process communication loop or segment. At block 306, the handheld field maintenance tool queries each field device to obtain its physical location or coordinates as well as the terminal number that connects the field device to the process communication loop or segment. Preferably, the location or coordinates of the terminal are also provided to the handheld field maintenance tool by the field device. At block 308, the handheld field maintenance tool provides an indication to the technician relative to a terminal. In this way, the technician may ensure that the correct field device is disconnected from the terminal when it is maintained without the necessity of tracing back the wires.

0029<figref idref="f0006">FIG. 6</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention. Method 320 begins at block 322 where a handheld field maintenance tool is communicatively coupled to a field device. Next, at block 324, the handheld field maintenance tool queries the field device to obtain its terminal block location. At block 326, the handheld field maintenance tool provides a map, or other suitable indication, to the technician via display 120 to guide the technician to the location of the terminal block of the field device.

0030<figref idref="f0007">FIG. 7</figref> is a flow diagram of a method of performing location-assisted field maintenance in accordance with an example useful for understanding the invention. Method 340 begins at block 342 where a technician selects a particular process asset or piece of equipment using a handheld field maintenance tool. Next, at block 344, the handheld field maintenance tool queries a local database, or a remote asset management system, to identify all field devices and/or process installation assets that are associated with the selected process asset or piece of equipment. At block 346, the handheld field maintenance tool displays all associated devices and assets on a map for the technician. In this way, the technician can easily find and interact with the various field devices and assets that are associated with the selected process asset.