Abstract:
A method of evaluating a potential location to add a wireless field device to an existing network of a plurality of existing wireless field devices is provided. The method includes placing a handheld field maintenance tool in the potential location and causing the handheld field maintenance tool to identify wireless field devices within communicative range of the potential location. Information related to wireless communication at the potential location is viewed. Methods are also provided for identifying a selected field device in a process installation using a handheld field maintenance tool.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 61/178,757, filed May 15, 2009, the content of which is hereby incorporated by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    In industrial settings, control systems are used to monitor and control industrial and chemical processes, and the like. Typically, the process control system performs 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. Field devices generally perform a function, such as sensing a parameter or operating upon the process, in a distributed control or process monitoring system. 
         [0003]    Some field devices include 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. Types of transducers include various analytical equipment, pressure sensors, thermistors, thermocouples, strain gauges, flow transmitters, positioners, actuators, solenoids, indicator lights, and others. 
         [0004]    Some process installations may involve highly volatile, or even explosive, environments. Accordingly, 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: 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. Examples of handheld field maintenance tools that comply with intrinsic safety requirements include those sold under trade designations Model 375 Field Communicator and Model 475 Field Communicator, available from Emerson Process Management of Austin, Tex. 
         [0005]    Typically, each field device also includes communication circuitry that is used for communicating with a process control room, or other circuitry, over a process control loop. Traditionally, analog field devices have been connected to the control room by two-wire process control current loops. In some installations, wireless technologies have begun to be used to communicate with field devices. Wireless operation simplifies field device wiring and set-up. 
         [0006]    One wireless process communication technology standard is known as the WirelessHART standard. The WirelessHART standard was published by the HART Communication Foundation in September 2007. Relevant portions of the Wireless HART® Specification include: HCF_Spec 13, revision 7.0; HART Specification 65—Wireless Physical Layer Specification; HART Specification 75—TDMA Data Link Layer Specification (TDMA refers to Time Division Multiple Access); HART Specification 85—Network Management Specification; HART Specification 155—Wireless Command Specification; and HART Specification 290—Wireless Devices Specification. 
         [0007]    Another wireless network communication technology is set forth in ISA100.11a. This technology proposes wireless communication at the 2.4 GHz frequency using radio circuitry in accordance with IEEE 802.15.4-2006. The ISA100.11 standard is maintained by the International Society of Automation (ISA). 
         [0008]    While these wireless communication technologies provide important advantages to the art of process control and communication, traditional techniques for maintaining and configuring wireless field devices that employ such communication is sometimes rendered inefficient. 
       SUMMARY 
       [0009]    A method of evaluating a potential location to add a wireless field device to an existing network of a plurality of existing wireless field devices is provided. The method includes placing a handheld field maintenance tool in the potential location and causing the handheld field maintenance tool to identify wireless field devices within communicative range of the potential location. Information related to wireless communication at the potential location is viewed. Methods are also provided for identifying a selected field device in a process installation using a handheld field maintenance tool. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]      FIG. 1  is a diagrammatic view of a wireless process control environment in which embodiments of the present invention are particularly useful. 
           [0011]      FIG. 2  is a diagrammatic view of a wireless process control environment in which a new wireless field device is being added. 
           [0012]      FIG. 3  is a diagrammatic view of a wireless process control environment in which a new wireless field device is being added in accordance with an embodiment of the present invention. 
           [0013]      FIG. 4  is a flow diagram of a method of evaluating a potential location for a new wireless field device in accordance with an embodiment of the present invention. 
           [0014]      FIG. 5  is a diagrammatic system block diagram of a handheld field maintenance tool in accordance with the embodiment of the present invention. 
           [0015]      FIG. 6  is a diagrammatic view of a method of locating a selected field device using a handheld field maintenance tool in accordance with an embodiment of the present invention. 
           [0016]      FIG. 7  is a flow diagram of a method of locating a selected field device using a handheld field maintenance tool in accordance with an embodiment of the present invention. 
           [0017]      FIG. 8  is a diagrammatic view of a method of locating a selected field device in accordance with another embodiment of the present invention. 
           [0018]      FIG. 9  is a flow diagram of a method of locating a selected field device in accordance with another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0019]      FIG. 1  is a diagrammatic view of a wireless process control environment in which embodiments of the present invention are particularly useful. As illustrated in  FIG. 1 , a plurality of wireless field devices  10  are communicatively coupled either directly or indirectly via wireless communication to wireless gateway  20 . Wireless field devices  10  are generally illustrated as wireless process variable transmitters, such as those sold under the trade designation Model 3051S wireless pressure transmitter, from Emerson Process Management, of Chanhassen, Minn. However, those skilled in the art will recognize that wireless field devices  10  can include other types of wireless process variable transmitters, as well as wireless actuators, valve positioners, et cetera. Wireless gateway  20  is configured to communicate with wireless field devices  10  using known wireless process communication protocols, such as the WirelessHART protocol described above. One example of a wireless gateway is sold under the trade designation Model 1420 by Emerson Process Management, of Chanhassen, Minn. Wireless gateway  20  includes one or more wired ports that are configured to couple to a local area network, such as an Ethernet local area network as illustrated at reference numeral  22 . By virtue of its wired connection, wireless gateway  20  can provide information to and receive information from any device coupled to local network  22  such as workstations  24  and  26 . 
         [0020]    The wireless field device network illustrated in  FIG. 1  can be considered a mesh network in that some of the field devices communicate with other field devices to pass their communication ultimately on to wireless gateway  20 . Thus, a field device that is located too far away from wireless gateway  20  to otherwise communicate directly, can still provide wireless process communication by virtue of communication through one or more other wireless field devices. 
         [0021]      FIG. 2  is a diagrammatic view of a wireless process control environment in which a new wireless field device is being added. When installation of a new wireless field device is required, the process is currently quite cumbersome. For wireless field devices, the physical position of the field device is often very important. This is because the physical position of the device will affect its proximity to other devices in the mesh network as well as proximity to a gateway. Further, sources of electromagnetic interference or physical obstructions may affect a field device more significantly at one position versus another. Thus, when a user is planning to install a new wireless field device into an existing network of wireless field devices, the user will generally perform a number of tasks and evaluations relative to the physical location of the new device. 
         [0022]    The user will typically evaluate physical distances between the proposed installation location illustrated at reference numeral  30  in  FIG. 2  and other connections points  10  (which in a self-organizing network could be any member of the network) and decide if the distances are within the expected effective communication range of the new wireless field device. 
         [0023]    In order to study location  30  in detail, the user will often walk into the field to location  30  and place a wireless test device at location  30 . Then, the user will return to one of workstations  24 ,  26  and access wireless gateway  20  and wait for the wireless test device to join the wireless network. The wireless test device can require up to 10 minutes to join the network. Once the test device does join the network, the user views communication characteristic information relative to the test device through a user interface provided by the wireless gateway. If proposed location  30  is satisfactory, the user then returns to location  30  and replaces the test device with the new wireless field device. However, if position  30  is not satisfactory, the entire process is repeated for an alternate location. If the user is exploring even a few potential locations, the process can quickly consume significant time. 
         [0024]      FIG. 3  is a diagrammatic view of a wireless process control environment in which a new wireless field device is being added in accordance with an embodiment of the present invention. The embodiment illustrated with respect to  FIG. 3  leverages a new ability of a handheld field maintenance tool to improve the process of adding new wireless field devices to existing wireless networks. Instead of deploying a test field device to proposed location  30 , handheld field maintenance tool  52  is used. Tool  52  has a wireless process communication module (Shown in  FIG. 5 ) that allows tool  52  to listen to and communicate directly with field devices  10 . Accordingly, when tool  52  is located at position  30 , a user can selected a function supplied by tool  52  to cause tool  52  to identify all wireless field devices  10  within communication range of position  30 . Tool  52  then displays the wireless field devices  10  within range of position  30 . This display may simply include the number of field devices with which tool  52  can communicate at position  30 . However, the display can be more sophisticated including a listing of device tags or MAC addresses, and the signal strength at position  30 . Additionally, tool  52  can also measure and report other connectivity issues, such as the presence of electromagnetic interference, other process communication networks, communication errors, or any other suitable parameter of interest to a technician deploying a new wireless field device. The embodiment described with respect to  FIG. 3  is believed to be particularly applicable to WirelessHART, but any other suitable wireless process communication protocol can be used. Moreover, while the embodiment described with respect to  FIG. 3 , is illustrated relative to handheld field maintenance tool  52 , any device that can communicate on the wireless sensor network and provide useful information to a technician or user may be employed. Thus, tool  52  could simply be a module or device that plugs into a laptop computer or other suitable mobile device. However, since the device is located, at least some of the time, in the field, it is preferred that tool  52  comply with at least one intrinsic safety specification, such as that listed above. 
         [0025]    Additionally, or alternatively, the signal quality at position  30  can be evaluated over time. Thus, if position  30  is susceptible to periodic electromagnetic interference, such a study would detect such interference thereby addressing a potentially intermittent communication difficulty. The study of position  30  can be done using a software application resident in one or more field devices  10 , gateway  20 , or preferably tool  52  to continually or periodically monitor signal strength of each network member over time. Preferably, the monitored signal strength information is stored and combined with geographic information (such as a map of the network) to provide a user with a graphical, intuitive depiction of signal quality as a function of position in the wireless process network. This map is termed a network heat map and can be used to graphically depict past history of signal strength to 1, 2, 3, 4 . . . et cetera devices in the area of position  30 . Further, the application, in some embodiments, illustrates the lowest signal strength to 1, 2, 3 et cetera wireless field devices. Further still, in some embodiments, the software application can recommend which wireless sensor network the new field device should join as well as provides an indication of anticipated communication reliability for the new wireless field device. 
         [0026]      FIG. 4  is a flow diagram of a method of evaluating a potential location for a new wireless field device in accordance with an embodiment of the present invention. Method  60  begins at block  62  where a handheld field maintenance tool is placed at a proposed location of a new wireless field device. Next, at block  64 , the handheld field maintenance tool identifies at least some wireless field devices within range of the handheld field maintenance tool. Preferably, the handheld field maintenance tool identifies all wireless field devices within range during block  64 . At block  66 , the handheld field maintenance tool provides information related to the wireless communication to a user via a display of the handheld field maintenance tool. This information may be the number of field devices found; the device tags of the field devices; the signal strength relative to each field device, et cetera. 
         [0027]      FIG. 5  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. 
         [0028]    Handheld field maintenance tool  52  includes at least one wireless process communication module  120 . Suitable examples for wireless process communication module  120  include a module that generates and/or receives proper signals in accordance with a known wireless communication protocol, such as the WirelessHART protocol described above. Another suitable wireless process communication protocol is that set forth in ISA100.11a described above. While  FIG. 5  shows a single wireless process communication module  120 , 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. 
         [0029]    Handheld field maintenance tool  52  also includes at least one secondary wireless communication protocol module  122 . Wireless communication protocol module  122  can communicate in accordance with one or more of the options shown in phantom in  FIG. 5 . Specifically, wireless communication protocol module  122  may communicate in accordance with a Bluetooth specification  124 ; a Wi-Fi specification  126 ; a known RFID specification  128 ; cellular communication techniques  130 ; and/or satellite communication  132 . These communication techniques and methodologies allow handheld field maintenance tool  52  to communicate directly with wireless gateway  20  either via direct wireless communication, or using the Internet to which a wireless gateway is generally coupled. While one wireless communication protocol module  122  is shown in  FIG. 5 , any suitable number may be used. Each of the wireless process communication protocol module  120  and wireless communication protocol module  122  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 to perform handheld field maintenance tasks. Wired process communication module  138  allows the handheld field maintenance tool 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, and others. 
         [0030]    Handheld field maintenance tool  52  can include a number of optional items that facilitate additional embodiments of the present invention. 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 . Additionally, tool  52  also preferably comprises compass module  152  coupled to controller  130  such that tool  52  can indicate the 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. 
         [0031]    The optional components of tool  52  are particularly useful in embodiments of the present invention 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 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. 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 find the device in the plant or process installation. 
         [0032]      FIG. 6  is a diagrammatic view of a process of finding a wireless field device using a handheld field maintenance tool to locate a selected field device in accordance with an embodiment of the present invention. Handheld field maintenance tool  100  can be identical to tool  52  described above with respect to  FIG. 5 . However, a different reference numeral is used because it need not be the same. Tool  100  includes a user interface (in the form of a keypad, navigation buttons, and a display) that allows a technician or engineer to select a specific field device to locate. Such selection will generally be in the form of selecting a device tag or identifier, but may take any suitable form. In the example shown in  FIG. 6 , the technician has selected wireless field device  206  among devices  200 ,  202 ,  204 , and  206 . While four field devices are illustrated, in reality, the field devices could number in the hundreds with field devices dispersed throughout the factory or process installation. Preferably, handheld field maintenance tool  100  contains a map of the process installation that is either pre-loaded into the handheld field maintenance tool, or communicated wirelessly to tool  100  through any suitable means. Additionally, in the event that handheld field maintenance tool  100  has previously interacted with the selected field device (such as during installation of the field device) handheld field maintenance tool  100  may have acquired information that relates the position (as indicated by the GPS module at the time of the previous interaction) to the device. This position information can be written to the field device, stored in handheld field maintenance tool  100  or both. It is also contemplated that handheld field maintenance tool  100  or a different handheld field maintenance tool can access the wireless field device using any suitable wireless communication and receive from the wireless field device location information indicative of a position of the wireless field device. Once the device tag is identified, the handheld field maintenance tool obtains position information, preferably from GPS module  150  relative to the position of tool  100 . Once tool  100  knows its own position, it generates an indication, vector, route, or other suitable directions to help the technician or engineer travel to the physical location of field device  206 . Preferably, the map includes an indication of tool  100  on the map so the user can gauge progress to the destination (field device  206 ) Additionally, since the technician is usually walking, and GPS heading information is based on movement, tool  100  may use its optional compass to provide the user with a directional indication  208  that points or leads the technician or engineer to the selected field device  206  even when the technician or engineer is standing still. Finally, since at least some process installations such as refineries may have field devices positioned tens or hundreds of feet above the ground, tool  100  can use tilt module  154  to cause the technician or engineer to incline tool  100  at an angle that causes the tool to be essentially aimed at field device  206 . Thus, if a user reaches a position where field device  206  is supposed to be, but field device  206  is actually located far overhead, tool  100  would indicate an angle of incline that would direct the user&#39;s attention to the proper elevation to locate the field device. 
         [0033]      FIG. 7  is a flow diagram of a method of locating a selected field device using a handheld field maintenance tool in accordance with an embodiment of the present invention. Method  70  begins at block  72  where an indication of a physical location of a selected field device is obtained by a handheld field maintenance tool. This may be done by accessing an internal pre-loaded database within the handheld field maintenance tool that correlates all device tags in the process installation to physical positions. Alternatively, the handheld field maintenance tool can generate a query based on the selected device identification to a suitable server or computing device in an asset management system to receive position information relative to the selected device. As set forth above, since the handheld field maintenance tool has ample wireless communication abilities, this query may be submitted while the user is in the field. Next, at block  74 , the handheld field maintenance tool determines its current position. This can be done in any suitable manner, but preferably includes accessing an internal GPS module, such as module  150 . Then, the controller of the handheld field maintenance tool processes the physical location of the selected field device and the current position of the handheld field maintenance tool to provide an indication to the user to direct the user toward the physical location of the selected wireless field device. 
         [0034]    Another aid for the technician or engineer&#39;s search for the wireless field device is illustrated with respect to  FIG. 8 . Specifically, once the user has selected a field device to locate, the handheld field maintenance tool  100  can communicate on the wireless sensor network in which the field device is located to cause the field device to generate a local annunciation to help capture the user&#39;s attention. This local annunciation  210  can be in the form of an audible alert or siren, a flashing light or indicator, or both. Thus, as the technician or engineer is walking near the field device, the field device&#39;s sounds and lights will help the technician or engineer focus on the desired field device. 
         [0035]      FIG. 9  is a flow diagram of a method of locating a selected field device in accordance with another embodiment of the present invention. Method  250  begins at block  252  where a user selects a wireless field device with a handheld field maintenance tool. Next, at block  254 , the handheld field maintenance tool generates suitable wireless communication, preferably wireless process communication, to cause the selected field device to generate a local annunciation. 
         [0036]    While each of the embodiments described with respect to  FIGS. 6 and 8  can be practiced separately, combinations of the embodiments are also useful. For example, the user can obtain and follow a map to arrive in the general area of the selected field device. Then, once handheld field maintenance tool senses proximity above a certain threshold to the field device, the handheld field maintenance tool can automatically interact with the field device through the wireless sensor network to cause the field device to generate the local annunciation and confirm the location of the field device. Further still, if the user reaches the location of the selected field device and cannot find it, the user may also obtain additional location assistance information using the handheld field maintenance tool. For example, the user may download an image of the field device located in its position. The user can then view the image and compare it to the user&#39;s physical reality to find the field device. 
         [0037]    Although the present invention has been described with reference to particular 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.