Automated field device

Abstract

An automation technology field device for determining a filling level (L) of a filling substance (2) in a container (3) and adapted to undergo direct high-pressure water or steam jet cleaning comprises: a fully welded metal field device housing (12) surrounding an inner space (13) and having an integrated interaction and / or viewing screen; a transmission / reception unit (14) which is designed to generate a radar signal (SHF) according to a defined radar principle and to determine a fill level (L) on the basis of the corresponding reception signal (RHF), by means of which the antenna (11), the generated radar signal (SHF) can be transmitted and then received after reflection, an interaction and / or display element (19), an interaction and / or display element (19) arranged in the interior space (13) of the field device housing (12) behind the interaction and / or viewing screen, the interaction and / or display element (19) being adapted to record a key pressure exerted by an operator on the interaction and / or viewing screen; and a radio unit which is arranged in the interior space (13) of the field device housing (12) behind the interaction and / or viewing screen for wireless data transmission.

Description

TECHNICAL FIELD

[0001] The present invention relates to field devices of automation technology for determining the filling level of a filling substance in a container. BACKGROUND

[0002] From the prior art it is known that field devices for industrial plants. Field devices are typically applied in process automation technology as well as in manufacturing automation technology. In principle, all devices are called field devices which are applied in the vicinity of a process and which deliver or process relevant information. Field devices are used for registering and / or influencing process variables. For registering process variables are measuring devices or sensors. This is for example for pressure and temperature measurement, conductivity measurement, flow measurement, etc. and records the corresponding process variables, pressure, temperature, conductivity, pH value, filling level, flow, etc. For influencing process variables are actuators. This is for example a pump or a valve which can influence the flow of a liquid in a pipe or a filling level in a container. Besides the above mentioned measuring devices and actuators are also remote I / O, radio adapters and in general devices which are arranged at the field level called field devices.

[0003] A large number of such field devices are manufactured and sold by the Endress+Hauser Group of companies.

[0004] For the filling level measurement of a filling substance in a container contactless measurement methods have proven themselves as they are robust and require little maintenance. In such cases, a "container" in the sense of the present invention also refers to a non-closed inclusion such as for example a barrel, a lake or an ocean or a flowing body of water. A further advantage of contactless measurement methods is their ability to virtually continuously measure the filling level. For continuous filling level measurement, mainly radar-based measurement methods are applied (in the context of the present invention the term "radar" refers to signals and electromagnetic waves with frequencies between 0.03 GHz and 300 GHz).

[0005] In such a case, the established measurement principle is the measurement principle of FMCW ("Frequency Modulated Continuous Wave"). The measurement principle of the distance measurement method based on FMCW radar relies on the transmission of a continuous radar signal with a modulated frequency. In such a case, the characteristic of FMCW is that the transmission frequency is periodically changed within a defined frequency band. In view of the regulatory specifications, the gradual development leads to the use of higher frequency bands with a standardized center frequency. Thus, in addition to the 6 GHz frequency band, the 26 GHz frequency band and the 79 GHz frequency band, at the same time, frequencies above 100 GHz are being implemented. It is advantageous for the higher frequencies to be able to use a larger absolute bandwidth (for example, 4 GHz in the case of the 100 GHz frequency band). In this way, a higher resolution and higher accuracy of the fill level measurement are achieved. The FMCW fill level measurement method is described, for example, in Offenlegungsschrift DE 10 2013 108 490 A1.

[0006] The radar signals are typically transmitted and received via a hollow conductor which serves as an antenna and is widened in the radiation direction, for example, similar to a horn antenna.

[0007] In the case of hygiene processes, there are particularly high requirements for the work and / or the cleanliness. An example of such a hygiene process is the application in the food industry, in which there is a risk that deposits and / or contaminants can degrade the storability and / or cause contamination of the foodstuffs that is harmful to health. For hygiene reasons, it is therefore important that the field devices free the gap and the edge of the container opening as far as possible from deposits in order to prevent the filling substance from depositing.

[0008] In addition, in order to meet these requirements, the housings of the field devices for fill level measurement are implemented in particular. For example, they are made of a metallic material such as, for example, 316 L stainless steel and / or are designed in such a way that there are as few sites as possible in which deposits and / or contaminants can adhere.

[0009] In addition, the housings of the field devices are implemented in such a way that they can be cleaned from the outside. For this purpose, they need to be implemented as devices that are waterproof and hermetically sealed. The International Electrotechnical Commission (IEC) has introduced an international protection code which classifies electrical devices in this respect and informs them about which environmental conditions they are suitable for and thus which environmental conditions they have to withstand. Of the defined protection types, for the present purpose, in particular two protection types are important for the development of housings for hygiene applications, namely IP68 and IP69. In such a case, the protection type IP68 provides protection against significant submersion, in particular also significant submersion in water at significant depth. The protection type IP69 ensures that liquids cannot penetrate at high pressure and high temperature. Such conditions can exist, for example, in the case of the use of high-pressure or steam-jet cleaning.

[0010] In addition to the requirements for the housing of field devices used in hygienic processes, there has recently been an increasing need to connect field devices to external tools such as smartphones / cellular phones, cloud services, etc., via wireless data transmission. For this purpose, radio modules are typically integrated into the housing of the field device to provide a radio interface for data exchange with the field device. However, for wireless connectivity to be possible, radio signals must pass through openings in the housing or a non-metallic area needs to be provided within the housing. Either choice can be critical to the hygienic process, leading to either a radio interface in the case of a field device with a fully welded metal housing, regardless of the requirements of the hygienic process, or accepting compromises in the housing architecture.

[0011] In the prior art, two variations have emerged in this case. The first variation specifies that the housing is implemented with a cover having threaded or bayonet stabilizing elements. The second variation specifies that the housing is implemented with a non-metallic top, such as plastic, placed on the upper end of the housing body.

[0012] The covered architecture does enable the use of displays and / or keys for field interaction and protection classes IP68 and / or IP69. However, a drawback is that in larger structures, the resulting residue accumulates at edges and / or joints, increasing production costs.

[0013] Non-metallic tops with integrated displays or keys used solely for field interaction with field equipment do not meet protection classes IP68 and / or IP69. Additionally, the transition from metal to plastic in the transition area means more residue buildup at the edges and / or joints. Summary of the Invention

[0014] The purpose of this invention is to solve the above-mentioned problems.

[0015] According to the present invention, the objective is achieved by the automated field device as described in claim 1.

[0016] The present invention provides an automated field device for determining the fill level of a container and suitable for direct high-pressure water or steam jet cleaning and / or for prolonged immersion in water to a significant depth, comprising: - A fully welded metal field equipment housing surrounding an internal space, preferably with an airtight seal, and featuring an integrated interactive and / or viewing screen; - The transmission / reception unit is designed to generate radar signals according to defined radar principles and determine the fill level based on the corresponding received signals. - An antenna, by means of which the generated radar signal can be transmitted and then received after reflection. - an interaction and / or display element arranged in the interior space of the live device housing behind the interaction and / or viewing screen, which is adapted to record key pressure exerted by the operator on the interaction and / or viewing screen; and - a radio unit arranged in the interior space of the live device housing behind the interaction and / or viewing screen for wireless data transmission.

[0017] According to the invention, a live device for automated technology for determining the filling level of a filling substance in a container is provided. The live device is embodied such that it has a completely welded metal housing and is able to transmit and receive radio signals in addition to radar signals in order to wirelessly communicate data. For this purpose, the invention provides a radio unit for wireless data transmission, which is arranged behind the interaction and / or viewing screen, which is preferably joined, in particular adhered, to the completely welded housing. The term completely welded housing here means a housing which initially consists of at least two components, for example a housing body and a cover, which, however, are welded to one another in the production of the live device such that the housing is permanently closed and the cover cannot be released from the housing body, for example by rotation or the like. In other words, this means that the housing can only be reopened by destructive methods. By the completely welded housing, the interior space in the housing can be hermetically sealed such that the live device is suitable for use in hygienic processes, since it can be cleaned by means of high-pressure or steam-jet devices and / or the housing provides protection in the case of a significant immersion in water at a significant depth for a significant length of time.

[0018] An advantageous form of embodiment of the live device of the invention can provide that the completely welded metal live device housing with integrated viewing screen is embodied such that the housing meets the requirements of the protection class IP68 with regard to significant immersion in water at a significant depth and / or the protection class IP69 with regard to exposure to direct high-pressure water or steam jets for cleaning, in particular the protection class IP68 and / or the protection class IP69 according to the standard IEC 60529, version 2.2 of 2013-08.

[0019] A further advantageous form of embodiment of the live device of the invention can provide that the interaction and / or viewing screen is joined, in particular adhered, to the live device housing.

[0020] A further advantageous form of embodiment of the live device of the invention can provide that the live device housing comprises an integrated recess for receiving the front film, and wherein the front film is located in the recess.

[0021] A further advantageous form of embodiment of the live device of the invention can provide that the recess is embodied such that the depth of the recess corresponds to at least one material thickness of the front film.

[0022] A further advantageous form of embodiment of the field device of the application can provide that the recess is embodied and adapted to the front membrane such that a peripheral gap is formed in the recess around the front membrane. In particular, embodiments of this form can provide that the peripheral gap has a maximum width of 0.2 mm, in particular 0.15 mm. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application will now be explained in more detail on the basis of the drawings, which are shown below.

[0024] Figure 1 is a radar-based field device for determining the fill level of a filling substance in a container, Figure 2 is a schematic sectional view of an automation field device designed for a hygienic application, and Figure 3 is a detailed view of a region of the field device housing behind which an interaction and / or display element is located. DETAILED DESCRIPTION

[0025] In order to understand the application, Figure 1 a container 3 containing a filling substance 2 is shown, the fill level L of which is to be determined. In such a case, the container 3 can extend to more than 100 m in height depending on the type of filling substance 2 and depending on the field of application. In order to be able to determine the fill level L, a radar-based field device 1 of automation technology is installed above the filling substance 2 at a known installation height h above the floor of the container 3. In such a case, the field device 1 is secured such that on a standardized container opening, the radar signal S HF , R HF can be transmitted from the antenna 23 into the container 3 and received after reflection on the filling substance surface. As Figure 1 is shown, the container opening, and thus the field device 1, is designed such that the antenna 23 radiates the radar signal S HF vertically downwards towards the filling substance 2 along a defined beam axis a, wherein in the illustrated example of embodiment the beam axis a extends perpendicular to the container lid due to the installation situation.

[0026] The transmitted radar signal S HF is reflected on the filling substance surface, the field device 1 receives the reflected radar signal R HF . In such a case, the resulting signal travel time t between transmission and reception of the radar signals S HF , R HF is proportionate to the distance d between the field device 1 and the filling substance 2 according to the following formula .

[0027] The parameter "c" is the medium-dependent radar propagation speed. In order to determine the signal travel time t, either a FMCW or a pulse travel time method can be implemented in the field device 1. Accordingly, the radar signal S HF is generated and the reception of the corresponding reception signal R HF takes place by means of a correspondingly designed transmission / reception unit 14 within the field device 1, which is coupled to the interior vessel interior remote region of the antenna 23. In the case of the FMCW method, the transmission / reception unit 14 can be designed, for example, on the basis of a phase control loop ("phase-locked loop"). In the case of the pulse travel time method, the transmission / reception unit can operate on the basis of the principle of pulse undersampling.

[0028] For example, after a corresponding calibration of the field device 1, the distance d can be associated with the measured signal travel time t. Then, when the installation height h is supplied in the field device 1, the field device 1 can determine the filling level L at least point by point according to the following formula: .

[0029] Figure 2 A schematic sectional view through an automated field device 10 for determining a filling level of a filling substance in a vessel according to the invention is shown. The field device 10 comprises a field device housing 12 which surrounds an interior space 13. The field device housing is a metal housing. In particular, it can be a stainless steel housing. Furthermore, the housing is a completely welded housing, i.e. a housing which can only be opened by destructive methods. This can be realized, for example, by a housing which is constructed, for example, of two parts, a housing body and a housing cover, which are welded together during manufacture.

[0030] The field device housing 12 can have at least sectionally rotationally symmetrical regions 17 in which the field contact plug 21 is or has been integrated. The field device 10 further comprises a transmission / reception unit 14 which is adapted, for example, as described above, to generate a radar signal S HF which is transmitted according to defined radar principles and to determine a filling level L on the basis of a corresponding reception signal R HF .

[0031] For providing and / or conditioning the sensor signal and located in the interior space 13 of the field device housing is an electronic circuit 15 which is formed for operating the transmission / reception unit 14, etc.

[0032] In the present example of the embodiment, the electronic circuit comprises three circuit boards, of which two circuit boards 15a and 15b are arranged in the longitudinal direction of the housing and one circuit board 15c is arranged in the transverse direction of the housing. However, the present application is not limited to this arrangement of the number of circuit boards in the longitudinal direction and / or in the transverse direction. Thus, for example, it is also possible to arrange only one or three circuit boards in the longitudinal direction. The circuit boards 15a, 15b, 15c are plugged together and thus electrically contacted via the corresponding plug connector and counter plug connector 15d. The plug connector and counter plug connector can be formed as rigid connectors as well as flexible connectors. Likewise, the plug connector and counter plug connector can be reversed.

[0033] The electronic circuit further comprises an interface electronics 20 having at least a first circuit board 25, which has a field contact plug 21 arranged at the circuit board edge in the longitudinal axis of the circuit board 25 and soldered to the circuit board edge. Data, in particular measurement values, and / or power, thus energy, can be transmitted from an external unit of, for example, a superordinate unit or another field device, to the field device 10 and / or from the field device 10 to an external unit of, for example, a superordinate unit or another field device, via the field contact plug 21.

[0034] The field contact plug 21 can be, in particular, a round connector, for example an M12 round connector. However, likewise, it can also be another available plug connector suitable for transmitting data and / or energy. For example, it can also be an Ethernet plug connector. Furthermore, the field contact plug 21 can also comprise a cable jacket through which lines for electrical contacting are guided to the interior of the field device.

[0035] The interface electronics 20 further comprises at least one counter plug connector 22, which can be arranged and placed on the first circuit board 25 such that the plug axis 23 is inclined or canted with respect to the main plane of the first circuit board 25. Via the counter plug connector 22 of the interface electronics, it is connected to one of the circuit boards of the electronic circuit via a matching plug connector 15e present therein. Both the plug connector and the counter plug connector can be rigid or flexible. Likewise, the positions of the plug connector and the counter plug connector can be reversed. Furthermore, electronic components for EMC and / or explosion protection 24 can be present on the first circuit board 25.

[0036] The electronic circuit 15 located in the field device 10 can be arranged at least partially in an electronics container 16, which has a seat in the field device housing and, in the given case, also serves as a circuit board for securing the electronic circuit. In such a case, the electronics container 16 substantially fits into the outer contour of the field device housing. Furthermore, the electronic circuit components located in the electronics container 16 can be surrounded by means of a cast potting compound 27.

[0037] The field device housing 12 further comprises a housing opening 18 through which the field contact plug is guided outwards. In order to be mechanically secured and / or oriented, thus positioned, a precisely fitting plug sleeve is pushed over the field contact plug and placed in or on the field device housing. The plug sleeve 26 is externally soldered to the field device housing. In order to hold the plug sleeve during the soldering process, this can be secured to the electronics container 16 by means of a securing means. This can take place, for example, via a catch mechanism arranged on the electronics container 16 in the field device housing. For example, a first securing element can be implemented by means of a catch geometry injected on the electronics container 16, for example in the form of a latch. In order to enable engagement or clamping, a circumferential recess is implemented on the plug sleeve 26 as a second securing element. By the interaction of the two securing elements, it is prevented that the field contact plug is influenced during the soldering process, for example by the dynamic range of the soldering unit or the protective gas flow, since the plug sleeve 26 is secured to the electronics container 16. Furthermore, the laser beam has free access to the soldering site.

[0038] At the upper end of the field device 10, the field device housing 12 comprises an interaction and / or display element 19 for display and / or interaction. The interaction and / or display element 19 can comprise, for example, a display for visualizing information. For interaction, the interaction and / or display element 19 can further comprise a capacitive key. This can be implemented, for example, by means of a corresponding capacitive film. It is also possible that the interaction and / or display element 19 is only one or more LEDs via which the status of the field device or other information is signaled. Furthermore, the interaction and / or display element 19 can also have optical keys for interacting with the field device.

[0039] In order to meet the requirements of the protection class IP68 and / or the protection class IP69, in particular the protection class IP68 and / or the protection class IP69 according to the standard IEC 60529, version 2.2 of August 2013, the interaction and / or display element 19 is arranged behind the interaction and / or viewing screen 11 provided in the field device housing. The interaction and / or viewing screen 11 can be joined, for example, by means of a joining method with the housing 12, in particular an adhesive method.

[0040] Additionally, the interactive and / or display element 19 can be arranged behind a front film 60 placed in the recess 12a of the field device housing. Such front films 60 are used in almost all branches of industry. Typically, these front films 60 are made of polyester or polycarbonate. The front film 60 can be arranged in a recess 12a provided in the field device housing 12.

[0041] Figure 3 The area of the field device housing 12 in which the interactive and / or display element 19 is arranged is shown in detail. In such a case, the front film 60 can be implemented as a self-adhesive film. Furthermore, the front film 60 can be printed on the rear side so that the print is protected from dust, moisture, chemical influences, scratches, heat, cold weather, wear and tear during transport or continuous use.

[0042] With regard to the recess 12a, this can be implemented such that the housing 12 has a continuous contour that provides a pocket for receiving the front film 60. The recess 12a can be formed, for example, by means of a punch formed during production of the housing 12. The recess 12a can further be implemented to provide a peripheral gap 12b or result required for assembly. This means that the recess can be slightly higher and / or wider than the height and / or width of the front film 60 to be placed into the recess. Ideally, the gap has a maximum width of 2 mm, in particular a maximum width of 0.15 mm. The recess can alternatively or additionally also be implemented such that the depth of the recess corresponds to at least one thickness of the front film, so that it is ensured that a lateral high-pressure water or steam jet cannot reach the rear side of the front film. In order to protect the interactive and / or display element 19, which is otherwise only protected by the front film, from the effects of a high-pressure water or steam jet, it can be arranged behind the housing 12 of the integrated viewing / interactive screen 11 in the interior space 13 of the field device.

[0043] For the best possible presentation, in particular the readability, of information on or from the interaction and / or display element, it can be necessary for the interaction and / or display element 19 to lie as flat as possible against and / or evenly on the rear side of the viewing / interaction screen 11. For this purpose, a display frame 30 can be used which, on the one hand, receives the interaction and / or display element 19 and, on the other hand, positions it appropriately behind the viewing / interaction screen 11. For this purpose, the display frame 30 can be fastened to a support plate 50 which is appropriately positioned in the interior space 13, so that the interaction and / or display element 19 arranged in the receiving region 37 and, in the given case, fastened there, is pressed against the viewing screen 11 by the display frame 30. The support plate can be a circuit board 50 which can be adapted, for example, to enable evaluation and / or driving and operation of the interaction and / or display element 19. In such a case, the display frame 30 can be guided via guide pins 35 which are oriented axially in corresponding holes of the circuit board 50. The display frame 30 is fastened via two retaining hooks 36 for fastening engagement on the display frame 30 distal to the circuit board 50.

[0044] Additionally, the display frame 30 described above together with the support and circuit board can be integrated in a display holder 40. In such a case, the display holder 40 can be implemented preferably such that this likewise comprises its own holder elements, in particular holder hooks, with which the display holder 40 is fastened to the support and circuit board 50. In this way, the display frame 30 with the interaction and / or display element 19, the circuit board 50 and the display holder 40 form a unit or assembly. Furthermore, the display holder 40 can also have the interaction and viewing screen 11.

[0045] According to the application, a radio unit 51 is additionally provided arranged in the interior space 13 of the field device housing 12 behind the interaction and / or viewing screen for wireless data transmission. The radio unit 51 is adapted to transmit and / or receive data wirelessly. The radio unit 51 can be arranged, for example, on a support plate 50 which serves as a circuit board in the area behind the interaction and / or viewing screen 11. The radio unit 51 can be, for example, a Bluetooth radio unit for wireless transmission of data by means of the Bluetooth standard or modified variants thereof, for example Bluetooth Low Energy. Alternatively, the radio module can also be a WLAN, ZigBee, NFC, IIoT, 5G or WirelessHART radio module. The data can be, for example, configuration and / or parameterization data for the field device.

[0046] List of reference signs

[0047] 2 Filling substance

[0048] 3 Container

[0049] 4 superior unit

[0050] 10 field device of automation technology

[0051] 11 viewing / interaction screen

[0052] 12 field device housing

[0053] 12a recess for receiving a front film

[0054] 12b peripheral gap

[0055] 13 interior space

[0056] 14 transmission / receiving unit

[0057] 15 electronic circuitry

[0058] 15a-15c circuit boards

[0059] 15d plug and counter plug connector

[0060] 15e plug connector

[0061] 16 electronic container

[0062] 16a lock catch

[0063] 17 rotationally symmetrical region

[0064] 18 housing recess

[0065] 19 interaction and / or display element

[0066] 20 interface electronics

[0067] 21 field contact plug

[0068] 22 counter plug connector of the interface electronics

[0069] 23 antenna

[0070] 24 electronic components, for example for EMC and / or explosion protection measures

[0071] 25 first circuit board of the interface electronics

[0072] 26 plug sleeve for the field contact plug

[0073] 27 potting compound

[0074] 30 display frame

[0075] 35 guide pin

[0076] 40 display holder

[0077] 50 support plate, e.g. in the form of a circuit board

[0078] 51 radio unit

[0079] 60 front membrane

Claims

1. An automated field device for determining a fill level (L) of a filling substance (2) in a container (3) and being adapted to be subjected to direct high-pressure water or steam jet cleaning and / or for being immersed in water at a significant depth for a significant duration, comprising: - a fully welded metal field device housing (12) surrounding an interior space (13), preferably having a gas-tight seal, and having an integrated interaction and / or viewing screen; - a transmission / reception unit (14) designed to generate radar signals (S HF ) according to a defined radar principle and to determine a fill level (L) on the basis of a corresponding reception signal (R HF ), - an antenna (11) by means of which the generated radar signals (S HF ) can be transmitted and then, after reflection, can be received, - an interaction and / or display element (19) arranged in the interior space (13) of the field device housing (12) behind the interaction and / or viewing screen, the interaction and / or display element (19) being adapted to register key pressures exerted by an operator on the interaction and / or viewing screen; and - a radio unit (51) arranged in the interior space (13) of the field device housing (12) behind the interaction and / or viewing screen (11) for wireless data transmission.

2. The automated field device according to the previous claim, wherein, A display frame (30) is provided, which is arranged in the interior space (13) of the fully welded metal field device housing (12) and is formed to receive the interaction and / or display element (19) and to apply it substantially flat and / or uniformly on the rear side of the interaction and / or viewing screen (11).

3. The automated field device according to the previous claim, wherein, The display frame (30) is fastened to a support plate (50) arranged in the interior space (13) so that the interaction and / or display element (19), which is preferably arranged in a receiving area (37) and is preferably fastened there, is pressed by the display frame (30) against the viewing screen (11).

4. The automated field device according to the previous claim, wherein, The support plate (50) comprises a circuit board, which is preferably formed to enable evaluation, driving and / or operation of the interaction and / or display element (19).

5. The automated field device according to the previous claim, wherein, The radio unit (51) is arranged on the circuit board (50) for a support plate in the area behind the interaction and / or viewing screen (11).

6. The automated field device according to one or more of the preceding claims, wherein, The radio unit (51) is adapted for wireless data transmission by means of Bluetooth standards or modified variants thereof, in particular Bluetooth Low Energy.

7. The automated field device of any one of claims 1 to 5, wherein, The radio unit (51) is adapted for wireless data transmission by means of WLAN, ZigBee, NFC, IIoT, 5G or wireless HART.

8. The automated field device according to one or more of the preceding claims, wherein, The fully welded metal field device housing (12) with integrated viewing screen is embodied so that the housing meets the requirements of the protection class IP68 with regard to significant immersion in water at a significant depth and / or the protection class IP69 with regard to exposure to direct high-pressure water or steam jets for cleaning, in particular the protection class IP68 and / or the protection class IP69 according to the standard IEC 60529, version 2.2 of 2013-08.

9. The automated field device according to one or more of the preceding claims, wherein, The interaction and / or viewing screen (11) is joined with the field device housing (12), in particular adhered to the field device housing (12).

10. The automated field device according to one or more of the preceding claims, wherein, The field device housing comprises an integrated recess (12a) for receiving a front membrane (60), and wherein the front membrane (60) is located in the recess (12a).

11. The automated field device according to one or more of the preceding claims, wherein, The recess (12a) is embodied such that a depth of the recess corresponds to at least one material thickness of the front membrane (60).

12. The automated field device according to one or more of the preceding claims, wherein, The recess (12a) is embodied such that a peripheral gap (12b) is formed in the recess (12a) around the front membrane (60) and is adapted to the front membrane (60).

13. The automated field device according to the previous claim, wherein, The peripheral gap (12b) has a maximum width of 0.2 mm, in particular 0.15 mm.

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