Abstract:
A mobile display device that selects a particular field device from a group of field devices and retrieves measurement data therefrom. The field device is selected by evaluating environment data which are captured by the display device without user input simplifying the measurement data display.

Description:
REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of the filing date of European Patent Application No. 16 153 935.8 filed on 2 Feb. 2016, the disclosure of which is hereby incorporated herein by reference. 
       FIELD OF THE INVENTION 
       [0002]    The invention relates to the transmission and display of field device measurement data. In particular, the invention relates to a mobile display device for selecting a field device from a group of field devices and for retrieving measurement data from the field device, to a measurement arrangement comprising a group of field devices and a mobile display device, to a method for selecting a field device from a group of field devices and for retrieving measurement data from the field device, to a program element and to a computer-readable medium. 
       TECHNICAL BACKGROUND 
       [0003]    Measurement data is retrieved from the field devices for example via a web server to which the user connects. This web server is communicatively connected to the field devices and obtains the measurement data therefrom. Alternatively, a user can also obtain the measurement data directly from the field device by connecting a display and control module or communication module, for example, to the field device. 
       SUMMARY 
       [0004]    A first aspect of the invention relates to a mobile display device for selecting a field device from a group of field devices and for retrieving measurement data from the field device. The display device comprises a sensor arrangement, a processing unit and a communication unit. 
         [0005]    The sensor arrangement is used to capture environment data which are associated with the location of the field device or with the container on which the field device is mounted or to which the field device is assigned. If the field device is a fill level measurement device, this container is used for storing the filling material of which the fill level is to be measured. 
         [0006]    The processing unit is used to analyse the environment data and to identify and/or select the field device on the basis of the analysis of the environment data. In other words, the processing unit can determine from the environment data captured by the sensor arrangement which field device from the group of field devices is to be selected. This can be made possible by the display device accessing a data set which contains information about which field device is mounted on which container. It should be noted that the analysis of the environment data and/or the determination of the field device may also be performed by an external server which communicates with the mobile display device. 
         [0007]    For example, it can be provided that the field device or container which is located closest to the mobile display device is selected and/or the field device or container towards which the mobile display device is directed is selected. 
         [0008]    A digital map may be stored on the server and/or the mobile display device such that the container towards which the mobile display device is directed can be selected automatically. An image analysis is not required. Geometrical or visual features of the container may also be recorded in this digital map, and therefore the server or the mobile display device can identify the container to which the mobile display device is directed using the captured image of the container. A barcode on the container or an identification number is not required. In particular, the respective container positions and the identification numbers of the field devices mounted on said container can be recorded in the digital map. 
         [0009]    The mobile display device comprises a position sensor, for example, and so it may be determined at any time where the mobile display device is located relative to the containers. 
         [0010]    It may be provided that these calculations take place on the server side and the server ensures that the appropriate field device is selected. 
         [0011]    The communication unit is used for retrieving measurement data from the field device which has been identified and selected. Measurement data can be retrieved automatically without the user needing to intervene or having to select a field device. Which field device is to be selected by the display device is determined solely by the captured environment data, and as a result of this the measurement data are retrieved automatically from the field device or server. However, it can also be provided that these measurement data are already retrieved at an earlier point in time so that they are already available in the display device after the field device has been selected. 
         [0012]    Therefore, the user can move through a warehouse, for example, in which a plurality of tanks are stored, each of these tanks having its own fill level measurement device. As the user walks through the warehouse, only the closest field device and/or the closest tank and the currently measured fill level therein are displayed to him in each case, for example. 
         [0013]    It should be noted at this point that the field device may be a fill level measurement device, but it may also be a pressure gauge or flow measuring instrument, or some other field device. The invention offers particular advantages for cases where a plurality of field devices are arranged at different locations, since this makes it possible for the user to get measurement data of interest to him displayed automatically without him needing to select a field device himself or having to trigger the measurement data retrieval. 
         [0014]    According to an embodiment of the invention, the mobile display device is designed to automatically retrieve the measurement data directly at the field device. 
         [0015]    According to another embodiment of the invention, the mobile display device is designed to automatically retrieve the measurement data on a server. 
         [0016]    The communication between the mobile display device and the field device or the server is generally wireless. 
         [0017]    According to another embodiment of the invention, the environment data include position data sent from the field device, orientation data of the mobile display device, image data of the container and/or barcode data or QR code data of a label affixed to the container. 
         [0018]    By evaluating these environment data, it is thus possible to identify the container (for example by image analysis of the recorded container image or by reading the barcode, etc.). It is also possible that the identity of the field device can be deduced from the position data sent by the field device, since the mobile display device has stored the positions and identities of the field devices in a digital map. In addition, the distance of the field device from the mobile display device can be determined from the sent position data, at least when the mobile display device comprises its own position sensor (for example a GPS sensor). 
         [0019]    The environment data can also contain height information, from which it can be determined at what height the user is located. From this height information, it can be for example inferred on what tank he is standing at that moment and an assignment of the closest field device can thus take place. The information relating to the environment can also contain information about the air pressure, from which the height can be derived, for example. Said information relating to the environment can also contain information relating to data received from the field device(s), transmission signal frequencies or transmitting powers, from which the transmitted field device and/or the distance thereof from the display device can be inferred. If, for example, the field device uses short-range communication such as Bluetooth, radio signals will only be received from the field device which is in close proximity (typically less than 30 m) to the display device. 
         [0020]    According to another embodiment of the invention, the mobile display device is a pair of smart glasses, a head-mounted display, a smartphone, a tablet or another type of mobile computer. It can be provided that the data from the field device that is of interest to the user is always depicted on his display for the field device which he is facing at that moment. As well as fill level data, it can also be provided that the position of the field device and/or the tank is shown on the display so that the user knows which tank it is. It can also be provided that the level of the tank can be depicted on the display, for example in the form of a coloured line or a rectangle which simulates the liquid in the container. In this way, the user can very quickly obtain an impression of the fill level situation in all the containers by turning his head, since this information can be superimposed graphically on the actual container. 
         [0021]    According to another aspect of the invention, a measurement arrangement for capturing and outputting measurement data is provided which comprises a group of field devices arranged at different locations and a mobile display device that is described above and in the following. The field devices are designed to transmit environment data, in particular position data, to the mobile display device, and the mobile display device is designed to select one of the field devices by using the environment data. 
         [0022]    The user himself therefore does not have to make a selection. Instead, the measurement data from the selected field device is transmitted to him automatically on the display device. 
         [0023]    Another aspect of the invention relates to a method for selecting a field device from a group of field devices and for retrieving measurement data from the field device, in which initially environment data are captured which are associated with the location of the container on which the field device is mounted. The environment data is then analysed, and subsequently the field device is identified and selected on the basis of the analysis. At the same time, before or after the field device has been identified and selected, the field device measurement data is automatically retrieved. This can all be in a computer-assisted manner without the user needing to intervene. After the field device has been selected, the measurement data thereof are displayed on a display. It can be provided that no measurement data are displayed other than the data from the selected field device. 
         [0024]    A further aspect of the invention relates to a program element which, when executed on a processor of a mobile display device, instructs the display device to carry out the steps described above and in the following. 
         [0025]    Another aspect of the invention relates to a computer-readable medium, on which the above-described program element is stored. 
         [0026]    In this case, the program element can be part of a piece of software, for example, that is stored on a processor of the mobile display device. The program element can also be a program element which, by way of an update, instructs an existing program to use the invention. 
         [0027]    In the following, embodiments of the invention will be described with reference to the figures. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0028]      FIG. 1  shows a measurement arrangement according to an embodiment of the invention. 
           [0029]      FIG. 2  is a flow diagram of a method according to an embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0030]    The views in the drawings are schematic and not to scale. 
         [0031]      FIG. 1  shows a measurement arrangement  100  according to an embodiment of the invention. The measurement arrangement comprises a plurality of filling material containers or tanks  104 , of which only one is shown for reasons of clarity. In each tank, a fill level measurement device  102  is fitted which can determine the fill level of the filling material stored in the container. However, a tank and fill level measurement device are only one embodiment. As well as a fill level measurement device, the field device can also be another sensor, for example a pressure sensor or a flow sensor. 
         [0032]    A label  107  is affixed to the tank, on which label a barcode or QR code is depicted. 
         [0033]    The system  100  further comprises a web server  103  and a mobile display device  101 . The web server, display device and field device can communicate with one another wirelessly. In this way, the field device  102  can transmit measurement data to the server or web server  103 , which measurement data are then called up from the server by the display device  101 . It can also be provided that the field device directly transmits measurement data to the display device. 
         [0034]    For this purpose, the display device comprises an antenna  106  which can also act as a sensor in order to capture environment data. The processing unit  105  of the display device evaluates the captured environment data and then optionally triggers a measurement data request to the server and/or the field device. However, the measurement data may also have been made available previously. The measurement data received can then be displayed on the display  108 . More particularly, this display is triggered by the evaluation of the environment data. 
         [0035]    The field device  102  of which the data is intended to be retrieved and displayed is therefore selected by analysing the environment data captured by the display device. 
         [0036]    The display device  106  is, for example, a smartphone, a tablet, a watch, a pair of smart glasses, a “HoloLens”, a wristband, a head-mounted display or a “wearable”. 
         [0037]    The display device is capable of proactively selecting the relevant field device, as a result of which automatic transmission of the relevant measurement data is triggered. This selection is made using the captured environment data. 
         [0038]    The measured values from the field device  102  are transmitted continuously, for example, to the web server  103 . If the user enters the tank farm in which the container  104  is located, the tanks relevant to the user are identified using the environment data captured by the display device and the measurement data is subsequently (or even before the user has entered the tank farm) loaded on the user&#39;s display device. If the user approaches a particular tank/plurality of tanks, the fill level data, for example, is displayed on his display device; which tank(s) he is approaching can be identified by the environment data. The fill level data are displayed to the user without manual selection, and therefore maximum user convenience is ensured. 
         [0039]    The display device is capable of capturing a plurality of different environment data, for example position data of the field devices and/or the display device itself, the height at which the display device is located, the three-dimensional angle of inclination of the display device, which shows the direction in which the display device points, the air pressure, radio reception of particular data or frequencies of the field device and/or visual identification features such as barcode/QR code or tank view. 
         [0040]    By way of example, the display device can be programmed to always display the field device that is located closest to the mobile display device, or the latest current measurement data thereof. Another option for identifying the field device in which the user could be interested at a specific time is that of measuring the height at which the user is positioned. If all containers in the space have a different height, the corresponding container and thus also the field device can be identified by means of the measured height information. The measurement data currently measured by the field device are subsequently displayed on the display device. 
         [0041]      FIG. 2  shows a flow diagram of a method according to an embodiment of the invention. In step  201 , environment data are captured which are associated with the location of a container on which the field device is mounted. In step  202 , the captured environment data are analysed. As an intermediate result of this analysis, it is determined that three containers are located in the angle of vision of the user (or of the smart glasses worn by the user). In step  204 , the container which is closest to the user (or the mobile display device thereof) is selected from among these three containers and, in step  205 , the measurement data captured most recently by said measurement device are shown on the display device. 
         [0042]    At any time during the method, the measurement data from all of the field devices or at least the selected field device can be retrieved and loaded onto the display device (either directly from the field device or via the server), and therefore said data can be displayed as promptly as possible. This is then particularly advantageous when the user rapidly changes his line of vision or the orientation of his wearable device or moves quickly through the space, meaning that different tanks must be selected and thus different fill levels must be displayed relatively quickly one after the other. 
         [0043]    For the sake of completeness, it should be noted that “comprising” and “having” do not exclude the possibility of other elements or steps, and the indefinite articles “an” or “a” do not exclude the possibility of a plurality. It should further be noted that features or steps which have been described with reference to one of the above embodiments may also be used in combination with other features or steps of other above-described embodiments. Reference numerals in the claims should not be treated as limiting.