Field device adapter for wireless data transfer

Abstract

The invention relates to a field device adapter for wireless data transfer (5) for connection to an interface (15) which is internal to a field device and is provided for a display (14) of the field device (1), which adapter has adapter electronics comprising at least the following: - an interface (5a) for connection to the interface (15) which is internal to the field device; - a radio module (6); - an energy store (18) designed to store energy transferred via the interface (5a) and to supply the radio module (6) with energy as needed; - an adjustable output voltage up converter (17) which is connected to the interface (5a) and can be adjusted via a feedback input (17c); - a charge controller (20) which is connected to the output of the output voltage up converter (17) and controls the charging process of the energy store (18); - an explosion-protection unit (21) which is connected between the charge controller (20) and the energy store (18); - wherein the feedback input (17c) of the output voltage up converter (17) is wired in such a way that a temperature dependency of the explosion-protection unit (21) is compensated by adjusting the output voltage of the output voltage up converter (17).

Description

[0001] Field device adapter for wireless data transmission

[0002] The invention relates to a field device adapter for wireless data transmission for connection to an internal field device interface provided for a display of a field device, an automation system and a method for operating a field device adapter for wireless data transmission.

[0003] In process automation technology, field devices are often used to record and / or influence process variables. Sensors such as level gauges, flow meters, pressure and temperature gauges, pH and redox potential meters, conductivity meters, etc., are used to record process variables, measuring the corresponding process variables: level, flow, pressure, temperature, pH value, or conductivity. Field devices are essentially all devices that are used close to the process and that provide or process-relevant information.

[0004] A large number of such field devices are manufactured and distributed by Endress + Hauser.

[0005] Currently, many existing automation systems still use two-wire field devices that are connected to a higher-level unit, such as a PLC control unit, via a two-wire cable. These two-wire field devices are designed so that power is supplied via the two-wire cable. Furthermore, they are designed so that the measured or control values, as the main process variable, are communicated, i.e., transmitted, via the two-wire cable in the form of an analog 4-20 mA signal. In addition to their primary function of generating measured values, modern field devices offer numerous additional functionalities that support the efficient and safe management of the process being monitored. These include functions such as self-monitoring of the field device, saving measured values, generating control signals for actuators, etc.

[0006] Because they are supplied via a two-wire cable, field devices are generally severely limited in terms of their power supply. This means that the individual electrical components are usually coordinated in such a way that the total power requirement of the field device just does not exceed the maximum power available via the two-wire cable. Due to the limited power available, it is not easily possible to retrofit such two-wire field devices, for example, with a field device adapter for wireless data transmission. In order to still be able to operate energy-intensive electronic components in a field device, energy storage devices are used that are charged using the power provided by the two-wire cable and discharged again when needed.

[0007] To charge such energy storage devices at maximum power, a charge controller is typically used to maintain the voltage at the energy storage device at a maximum point. Furthermore, for explosion protection reasons, it is necessary to prevent any backfeeding via the energy storage devices. For this purpose, explosion-proof units are typically installed upstream of the energy storage device to prevent backfeeding.

[0008] The disadvantage of this protective measure, however, is that the explosion-proof units are subject to high temperature influences, so that the voltage applied across the explosion-proof unit changes with temperature. When designing or constructing such circuits, this means that the voltage at the energy storage device must be somewhat higher than is fundamentally necessary, since this voltage can drop in the event of a temperature change. In other words, the voltage at the energy storage device is deliberately set higher than necessary in order to compensate for the temperature influence. This, in turn, results in high power dissipation.

[0009] The invention is based on the object of showing a possibility of how an energy storage device protected by an explosion protection unit can be connected with a lower power loss.

[0010] The object is achieved according to the invention by the field device adapter for wireless data transmission according to patent claim 1, the automation technology system according to patent claim 8 and the method according to patent claim 10.

[0011] The field device adapter according to the invention for wireless data transmission for connection to an internal field device interface provided for a display of a field device with adapter electronics comprises at least the following: an interface for connection to the internal field device interface of the field device instead of the display provided for this purpose, so that data and / or energy can be exchanged between the field device adapter and the field device; a radio module which is at least configured to wirelessly transmit a data packet according to a standard of a low-power wide area network; an energy storage device which is configured to store energy transmitted via the interface and to supply the radio module with energy as needed;an adjustable output voltage boost converter connected to the interface on the input side, which converts an input voltage applied to the interface to a higher output voltage applied to an output, wherein the output voltage is adjustable via a feedback input; a charge controller connected to the output of the output voltage boost converter, which is at least configured to regulate the charging of the energy storage device; an explosion-proof unit connected between the charge controller and the energy storage device and configured to prevent unwanted feedback of energy by the energy storage device, wherein the explosion-proof unit has a temperature dependency, by means of which a voltage applied across the explosion-proof unit changes depending on the temperature;wherein the feedback input of the output voltage boost converter is wired such that a temperature dependence of the explosion-proof unit is compensated by adjusting the output voltage of the output voltage boost converter;

[0012] An advantageous embodiment of the field device adapter according to the invention provides that the explosion-proof unit comprises at least one, preferably several, series-connected diodes, particularly preferably exactly three series-connected diodes, which are arranged such that a cathode of the respective diode is directed toward the energy storage device. In particular, the embodiment can provide that the diode(s) are Schottky diodes.

[0013] A further advantageous embodiment of the field device adapter according to the invention provides that the feedback input of the output voltage boost converter is connected to a temperature-dependent component in such a way that a voltage applied to the feedback input changes substantially opposite to a voltage applied across the explosion-proof unit which changes due to a temperature change.

[0014] A further advantageous embodiment of the field device adapter according to the invention provides that the feedback input of the output voltage boost converter is connected to a center tap of a voltage divider, wherein the voltage divider is connected to the output of the output voltage boost converter and furthermore a diode is introduced in an upper part of the voltage divider such that a voltage at the feedback input increases with increasing temperature at the diode introduced in the upper part of the voltage divider, so that a lower voltage is established at the output of the output voltage boost converter.

[0015] An alternative embodiment of the field device adapter according to the invention provides that the feedback input of the output voltage boost converter is connected to a center tap of a voltage divider, wherein the voltage divider is connected to the energy storage device and furthermore a diode is introduced in an upper part of the voltage divider such that a voltage at the feedback input increases with increasing temperature at the diode introduced in the upper part of the voltage divider, so that a lower voltage is established at the output of the output voltage boost converter.

[0016] A further advantageous embodiment of the field device adapter according to the invention provides that the diode or diodes of the explosion protection unit are Schottky diodes and the diode of the voltage divider is a silicon diode.

[0017] Yet another advantageous embodiment of the field device adapter according to the invention provides that the charge controller is at least configured to charge the energy storage device with a maximum possible power.

[0018] The invention further relates to an automation system comprising a field device and a field device adapter for wireless data transmission according to one of the previously described embodiments, wherein the field device has field device electronics with a field device-internal interface for a display and the field device adapter with the interface is electrically connected to the field device-internal interface via a cable.

[0019] A further advantageous embodiment of the automation technology system according to the invention provides that the field device further comprises a display mount for mechanically securing the display, and the field device electronics are positioned in the field device such that the display mount is arranged in a housing section with a transparent housing wall. The field device adapter is designed with an outer contour corresponding to an outer contour of the display, and the field device adapter is inserted into the display mount for mechanical fixation instead of the display, so that the field device comprises the field device adapter mechanically held in the display mount instead of the display. The invention further relates to a method for operating a field device adapter for wireless data transmission according to one of the previously described embodiments on a field device, comprising the following steps:

[0020] Exposing an internal interface of the field device to which a display of the field device can be electrically connected;

[0021] Connecting the field device adapter to the field device internal interface so that the field device adapter is electrically connected to the field device internal interface instead of the display.

[0022] The invention is explained in more detail with reference to the following drawings. It shows:

[0023] Fig. 1: a schematic representation of a field device in which a factory-provided display can be or has been subsequently converted for wireless data transmission by a field device adapter designed according to the invention, and

[0024] Fig. 2: an embodiment of an inventive circuit of the feedback input of the output voltage boost converter.

[0025] Figure 1 shows a two-wire field device 1, which comprises a preferably metallic housing 2 in which field device electronics 4 are arranged. The field device 1 is designed such that it has connection terminals 13, via which a two-wire line 12 is or can be electrically connected. The field device electronics 4 and thus the field device 1 are connected via the two-wire line 12 to a higher-level unit (not separately shown in Fig. 1) in order to communicate data with the higher-level unit via wire. The measured values ​​are communicated as the main process variable via the two-wire line 12 in analog form in the form of a 4-20 mA current signal, by providing a corresponding current value of the 4-20 mA current signal by the field device electronics. Other data, which may include, for example, parameters of the field device, are transmitted in the form of a digital two-wire signal, for example according to the HART standard.

[0026] Furthermore, the field device electronics 4 is also supplied with power via the two-wire cable or the 4-20 mA current signal. For this purpose, an operating power is made available to the field device electronics depending on a terminal voltage Uk applied to the connection terminals and the 4-20 mA current signal. The terminal voltage Uk usually has a minimum voltage value of approximately 10 V, so that a minimum operating power for the field device electronics of Pmin = 10 V * 4 mA = 40 mW results. In principle, however, the terminal voltage can also have a different value, e.g. a value in the range 10-30 V, so that the minimum operating power available to the field device also changes. To ensure safe operation of the field device 1, the field device electronics 4 is designed in such a way that all functions, in particular the acquisition or setting of measured values, the processing of these and the transmission orSetting a corresponding current value of the 4-20 mA current signal can be carried out using the minimum operating power Pmin.

[0027] Furthermore, the field device electronics 4 are set up at the factory, i.e. by the field device manufacturer, so that part of the minimum operating power is permanently available for a display for showing, for example, measured or set values ​​or other data, such as parameters or configuration values ​​of the field device, etc.

[0028] The display 14, which is designed either as part of the field device electronics or as a separate unit, is connected or connectable to the field device electronics via an internal field device interface. The field device can further comprise a display mount or holder for mechanically securing the display. The display mount can, for example, be designed as part of the field device electronics. The display mount can further be arranged in the field device such that a display held therein is located in a housing section with a transparent housing wall, for example, a housing cover.

[0029] Fig. 1 also shows a field device adapter 5 with adapter electronics for connecting to the internal field device interface 15 provided for the display 14 by means of a cable, so that the field device 1 can be subsequently converted for wireless data transmission, i.e., after it has already been integrated into an automation system. For example, the field device adapter 5 can be installed by a service technician who mechanically removes the cover 2a of the housing 2 to expose the interface, detaches the connecting cable 14b to the display 14 from the interface 15, and then connects the field device adapter 5 to the interface 15 by means of a corresponding connecting cable.

[0030] In order to mechanically fix the field device adapter 5 in the holder 19 actually provided for the display 14, an outer contour of the field device adapter 5 can essentially correspond to an outer contour of the display 14a, so that the holder 19 can accommodate the field device adapter 5.

[0031] The adapter electronics further comprises a current limiting circuit 16 configured to limit a current I2 flowing via the interface 15 to a value, preferably requested by the field device 1, so that only maximum operating power is provided to the field device adapter via the interface. The current limiting circuit 16 can be configured to adjust the value to which the current I2 flowing via the interface 15 is limited, in particular to optimize it as a function of the terminal voltage Uk applied to the connection terminals 13 and the 4-20 mA current signal.

[0032] The adapter electronics further comprise an adjustable output voltage boost converter 17, which is connected at an input 17a to an output 16b of the current limiting circuit 16. The output voltage boost converter 17 is configured to convert an input voltage applied to its input or the output of the current limiting circuit to an output voltage that is higher than the input voltage. For example, the output voltage boost converter 17 can be configured to convert an input voltage to a higher output voltage. In the described embodiment, the output voltage boost converter 17 converts from approximately 3 V to approximately 3.9 V, which is provided at an output of the output voltage boost converter 17b. Furthermore, the output voltage boost converter 17 is configured such that the output voltage can be adjusted via a feedback input 17c.The feedback input 17c of the output voltage boost converter 17 is wired according to the invention in such a way that a temperature dependence of an explosion-proof unit 21, which will be described in more detail later, is compensated by adjusting the output voltage of the output voltage boost converter. For reasons of clarity, the feedback input 17c and its wiring are not shown in detail in Fig. 1. For this purpose, reference is made to Fig. 2.

[0033] A charge controller 20 is connected to the output 17b of the output voltage boost converter 17 via one input, which charge controller is at least configured to regulate the charging of the energy storage device. For this purpose, the charge controller 20 can have an operational amplifier N1 and a metal oxide semiconductor field-effect transistor (MOSFET) V1. The charge controller 20 can be designed in particular to charge the energy storage device 18 with the maximum possible power. This can be achieved, for example, by monitoring the input of the output voltage boost converter 17a, e.g., by the operational amplifier N1, for a possible voltage drop, and in the event of such a voltage drop, the charging or the charging current is regulated accordingly, e.g., by the MOSFET. In this way, the energy storage device can be charged at the maximum possible charging point.

[0034] To enable the field device adapter to be operated in potentially explosive atmospheres, the adapter electronics also include a so-called Ex protection unit 21. The abbreviation "Ex" stands for explosion protection. Corresponding protection principles for this have been defined in the IEC EN DIN 60079-ff standard. According to this standard, circuitry measures for electronics for use in potentially explosive atmospheres are defined based on the applicable types of protection. One of these types of protection is "intrinsic safety" (Ex-i marking, IEC EN DIN 60079-11, June 2012 edition).

[0035] The "intrinsic safety" type of protection is based on the principle of current and voltage limitation in an electrical circuit. The energy in the circuit that could potentially ignite an explosive atmosphere is limited in such a way that neither sparks nor excessive heating of the electrical components can ignite the surrounding explosive atmosphere. For this reason, the explosion-proof unit 21 is connected between the charge controller 20 and the energy storage device 18 and is designed to prevent unintentional energy feed-back from the energy storage device 18.

[0036] The explosion-proof unit 21 is temperature-dependent. This means that a voltage applied across the explosion-proof unit changes depending on the temperature to which the explosion-proof unit is exposed. The explosion-proof unit can, for example, comprise one or more series-connected diodes, as shown in Fig. 2. Preferably, three diodes D2, D3, and D4 are connected in series between the charge controller and the energy storage device 18. The diodes are incorporated into the adapter electronics in such a way that a cathode of the respective diode is directed toward the energy storage device 18, which will be described in more detail later, so that unwanted feedback of energy by the energy storage device can be prevented and the field device adapter is designed for use in potentially explosive atmospheres.If the explosion-proof unit includes one or more silicon diodes, the forward voltage of the respective diode can drop by approximately 2 mV / K at a constant current through the diode. A preferred embodiment provides for the diode(s) to be Schottky diodes, as these exhibit a lower temperature dependence than 2 mV / K.

[0037] A rechargeable energy storage device 18 is connected to an input at the output of the explosion-proof unit 21, so that the output voltage provided by the boost converter 17 charges the energy storage device 18. The energy storage device 18 can, for example, comprise one or more capacitors. Due to their high storage capacity combined with their relatively small size, supercapacitors, such as a hybrid pulse capacitor (HPC) or a hybrid layer capacitor (HLC), have proven particularly preferred. The adapter electronics further comprise a radio module 6 with a radio antenna 9, which is at least designed to transmit data packets wirelessly. The radio module 6 is, in particular, configured to transmit the data packets in accordance with the LTE Cat NB1 standard of Release 13 of the 3GPP, published in June 2016.

[0038] In order to ensure sufficient energy is available to transmit a single data packet, the adapter electronics can be configured to monitor the charge state or charge level of the energy storage device 18 and, depending on the charge state, provide the radio module 6 with the energy required to transmit the data packet. For this purpose, the adapter electronics can provide a logic unit 10, for example, a microprocessor and / or a Schmitt trigger circuit.

[0039] In addition, the adapter electronics can be configured to convert the data originating from the field device 1 via the field device-internal interface 15 into data packets of a constant size. This means that all data packets transmitted one after the other by the radio module 6 have the same size. Due to the constant size of the data packets, the adapter electronics can also be configured to compare a current charge level of the energy storage device 18 with a constant predetermined charge level and, upon reaching the predetermined charge level, to make the energy stored in the energy storage device 16 available to the radio module 6 for transmitting a data packet. The predetermined charge level is dimensioned such that the energy stored in the energy storage device 16 is just sufficient for the radio module 6 to transmit a single data packet. In this way, data packets can be transmitted at a constant time interval, e.g.every hour, every day, etc., through the adapter.

[0040] Alternatively, the adapter electronics can be configured to convert the data originating from the field device 1 via the field device-internal interface 15 into data packets of varying sizes. Due to the varying sizes of the data packets, the adapter electronics 10, 16, 17, 18 can also be configured to adapt the size to a currently determined charge level of the energy storage device 18, so that the radio module 6 transmits data packets of varying sizes. This means that the radio module 6 transmits the data packets as soon as the energy stored in the energy storage device 18 is sufficient. The time interval between the successively transmitted data packets is therefore not necessarily constant. Fig. 2 shows an exemplary embodiment of an inventive circuit for the feedback input 17c of the output voltage boost converter 17.According to the exemplary embodiment, the feedback input 17c of the output voltage boost converter 17 is connected to a center tap of a voltage divider, which in turn is connected to the output of the output voltage boost converter 17. The voltage divider comprises two series-connected resistors R1, R2, which are selected and dimensioned accordingly to produce the desired output voltage, 3.9V in the present exemplary embodiment, at the output voltage boost converter 17.

[0041] In order to compensate for a temperature dependence of the explosion-proof unit 21, in particular of the diode(s), a further temperature-sensitive diode D1 is arranged in the upper part of the voltage divider R1, R2. The diode D1 is connected with an anode to the output of the output voltage boost converter 17 and with a cathode to the resistor R1 in the direction of the center tap. This diode D1 has a temperature dependence typical for diodes, so that a lower forward voltage is achieved at a higher temperature and, conversely, a lower forward voltage is achieved at a higher temperature. A particularly preferred embodiment provides for Schottky diodes to be selected as the diode(s) of the explosion-proof unit and a silicon diode as the diode in the voltage divider.

[0042] According to an alternative embodiment of the inventive wiring of the feedback input of the output voltage boost converter 17, the voltage divider is not connected to the output of the output voltage boost converter, but rather to the energy storage device 18. This is illustrated in Fig. 2 by a dashed connecting line 22, wherein, according to this embodiment, the connection of the voltage divider to the output of the output voltage boost converter 17 does not exist.

[0043] By wiring the output voltage boost converter 17 according to the invention, the temperature dependence of the explosion-proof unit 21 can be compensated by adjusting the output voltage of the output voltage boost converter 17 via the feedback input 17c. For example, if the temperature at the explosion-proof unit 21 increases, the forward or forward voltage of the individual diodes of the explosion-proof unit decreases, so that a voltage applied across the explosion-proof unit also decreases. At the same time, however, a voltage applied to the feedback input 17c increases because the forward or forward voltage of the diode D1 arranged in the upper part of the voltage divider, which is also exposed to the increasing temperature, also decreases. This in turn leads to the voltage conditions at the voltage divider changing in such a way that the voltage at the center point increases, so that a higher voltage is applied to the feedback input 17c.This causes the output voltage boost converter 17 to clock lower and thus the output voltage at the output voltage boost converter 17 to drop.

[0044] Conversely, when the temperature at the explosion-proof unit 21 drops, the forward or forward voltage of the individual diodes D2, D3, and D4 increases, so that a voltage applied across the explosion-proof unit 21 also increases. This, in turn, causes the voltage ratios at the voltage divider to change such that the voltage at the center point drops, resulting in a lower voltage at the feedback input 17c. This causes the output voltage boost converter 17 to clock higher, thus increasing the output voltage at the output voltage boost converter 17.

[0045] List of reference symbols

[0046] 1 field device

[0047] 2 Housing of the field device

[0048] 2a Cover of the housing

[0049] 4 Field device electronics

[0050] 5 field device adapters

[0051] 5a Interface of the field device adapter

[0052] 6 radio module

[0053] 7 Housing of the field device adapter

[0054] 9 radio antenna

[0055] 10 Logic unit

[0056] 12 two-wire cable

[0057] 13 Connection terminal

[0058] 14 Display

[0059] 14a Outer contour of the display

[0060] 14b Display connection cable

[0061] 15 Field device internal interface

[0062] 16 Current limiting circuit

[0063] 16a Input of the current limiting circuit

[0064] 16b Output of the current limiting circuit

[0065] 17 Output voltage boost converter

[0066] 17a Input of the output voltage boost converter

[0067] 17b Output of the output voltage boost converter

[0068] 17c Feedback input

[0069] 18 Energy storage / capacitor

[0070] 18a Input of the energy storage

[0071] 18b Output of the energy storage

[0072] 19 Display mount or holder

[0073] 20 charge controllers

[0074] 21 Ex-protection unit

[0075] 22 connecting line

[0076] 11 Current flowing through the two-wire line

[0077] I2 Current flowing through the field device internal interface

[0078] Pmin minimum operating power

[0079] Uk terminal voltage

[0080] R1 , R2 resistors of the voltage divider

[0081] D1 diode in the upper part of the voltage divider

[0082] D2, D3, D4 diodes of the explosion protection unit

Claims

Patent claims 1. Field device adapter for wireless data transmission (5) for connection to an internal field device interface (15) provided for a display (14) of a field device (1), comprising adapter electronics comprising at least the following: an interface (5a) for connection to the internal field device interface (15) of the field device instead of the display provided for this purpose, so that data and / or energy can be exchanged between the field device adapter and the field device; a radio module (6) which is at least configured to wirelessly transmit a data packet in accordance with a standard of a low-power wide area network; an energy storage device (18) which is configured to store energy transmitted via the interface (5a) and to supply the radio module (6) with energy as needed;an adjustable output voltage boost converter (17) connected to the interface (5a) on the input side, which converts an input voltage applied to the interface (5a) to a higher output voltage applied to an output, wherein the output voltage can be adjusted via a feedback input (17c); a charge controller (20) connected to the output of the output voltage boost converter (17) and which is at least designed to regulate the charging of the energy storage device (18); an explosion-proof unit (21) connected between the charge controller (20) and the energy storage device (18) and designed to prevent unwanted feedback of energy by the energy storage device (18), wherein the explosion-proof unit (21) has a temperature dependency, by means of which a voltage applied across the explosion-proof unit (21) changes depending on the temperature;wherein the feedback input (17c) of the output voltage boost converter (17) is wired such that a temperature dependence of the explosion-proof unit (21) is compensated by adjusting the output voltage of the output voltage boost converter (17); 2. Field device adapter according to the preceding claim, wherein the explosion protection unit (21) comprises at least one, preferably several diodes connected in series (D2, D3, D4), particularly preferably exactly three diodes connected in series, which is or are arranged such that a cathode of the respective diode is directed in the direction of the energy storage device (18).

3. Field device adapter according to the preceding claim, wherein the diode or diodes (D2, D3, D4) are Schottky diodes.

4. Field device adapter according to one or more of the preceding claims, wherein the feedback input (17c) of the output voltage step-up converter (17) is connected to a temperature-dependent component in such a way that a voltage applied to the feedback input (17c) changes substantially opposite to a voltage applied across the explosion-proof unit (21) which changes due to a temperature change.

5. Field device adapter according to one or more of the preceding claims, wherein the feedback input (17c) of the output voltage boost converter (17) is connected to a center tap of a voltage divider (R1, R2), wherein the voltage divider (R1, R2) is connected to the output of the output voltage boost converter (17) and furthermore a diode (D1) is introduced in an upper part of the voltage divider (R1, R2) such that a voltage at the feedback input (17c) increases with increasing temperature at the diode (D1) introduced in the upper part of the voltage divider, so that a lower voltage is established at the output of the output voltage boost converter (17b).

6. Field device adapter according to one or more of claims 1 to 4, wherein the feedback input (17c) of the output voltage step-up converter (17) is connected to a center tap of a voltage divider (R1, R2), wherein the voltage divider (R1, R2) is connected to the energy store (18) and furthermore a diode (D1) is introduced in an upper part of the voltage divider (R1, R2) such that a voltage at the feedback input (17c) increases with increasing temperature at the diode (D1) introduced in the upper part of the voltage divider (R1, R2), so that a lower voltage is established at the output of the output voltage step-up converter (17b).

7. Field device adapter according to one or more of the preceding claims, wherein the diode or diodes (D2, D3, D4) of the explosion protection unit (21) are Schottky diodes and the diode of the voltage divider (R1, R2) is a silicon diode.

8. Field device adapter according to one or more of the preceding claims, wherein the charging controller (20) is at least configured to charge the energy storage device (18) with a maximum possible power.

9. A system of automation technology comprising a field device and a field device adapter for wireless data transmission according to claim 1, wherein the field device (1) has a field device electronics (4) with a field device-internal interface (15) for a display (14) and the field device adapter (5) with the interface (5a) is electrically connected to the field device-internal interface (15) via a cable.

10. System according to the preceding claim, wherein the field device (1) further comprises a display holder (19) for mechanically fixing the display (14) and the field device electronics (4) is positioned in the field device (1) such that the display holder (19) is arranged in a housing section with a transparent housing wall (2a), wherein the field device adapter (5) is formed with an outer contour corresponding to an outer contour of the display (14a) and the field device adapter (5) is inserted into the display holder (19) for mechanical fixing instead of the display (14), so that the field device (1) comprises the field device adapter (5) mechanically held in the display holder (19) instead of the display (14).

11. A method for operating a field device adapter for wireless data transmission according to claim 1 on a field device, comprising the following steps: Exposing an internal interface of the field device to which a display of the field device can be electrically connected; Connecting the field device adapter to the field device internal interface so that the field device adapter is electrically connected to the field device internal interface instead of the display.

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