FIELD DEVICE ADAPTER FOR WIRELESS DATA TRANSMISSION

Description

[0001] The invention relates to a field device adapter for wireless data transmission and an automation system for detecting and / or setting a process variable.

[0002] In automation technology, particularly in process automation technology, field devices are often used to determine, optimize, and / or influence process variables. Sensors such as level gauges, flow meters, pressure and temperature gauges, conductivity meters, etc., are used to record process variables and measure the corresponding process variables: level, flow, pressure, temperature, or conductivity. Actuators such as valves or pumps, which can be used to change the flow of a liquid in a pipe section or the fill level in a container, are used to influence process variables. Field devices are essentially all devices that are used close to the process and that provide or process-relevant information.In the context of the invention, field devices also include remote I / Os (electrical interfaces), radio adapters or, in general, devices that are arranged at the field level.

[0003] A large number of such field devices are manufactured and distributed by Endress + Hauser.

[0004] WO 2019 / 007668 A1 discloses a field device adapter for wireless data transmission with a supply circuit integrated into a connecting line. US Pat. No. 9,768,641 B2 discloses a radio unit for a process automation system.

[0005] Currently, many existing automation systems still use two-wire field devices connected to a higher-level unit, such as a PLC control unit, via a two-wire cable. Two-wire field devices are designed in such a way that the measured or manipulated values, as the main process variables, are communicated, i.e., transmitted, via the two-wire cable in the form of an analog 4-20 mA signal. The HART protocol has proven particularly effective for transmitting all other data. This protocol overlays a frequency signal as a digital two-wire signal on the 4-20 mA analog current signal for data transmission. According to the HART protocol, data transmission switches between 1200 Hz and 2200 Hz, with the lower frequency representing a logical "1" and the higher frequency representing a logical "0."In this way, the slowly changing analog current signal remains unaffected by the frequency superposition, so that analog and digital communication are combined using HART.

[0006] However, with increasing digitalization, it is desirable for data to be transmitted not only via a two-wire cable, i.e., purely wired, but also wirelessly. This could be to wirelessly transfer the data to a database, such as a cloud database, and make it available there, or to wirelessly transfer data between the field device and a mobile control unit, for example, to wirelessly parameterize the field device via the mobile control unit.

[0007] It is therefore an object of the invention to propose a possibility by means of which existing field devices, which are actually designed for purely wired data transmission, can be retrofitted for wireless data communication.

[0008] The object is achieved by a field device adapter for wireless data transmission according to patent claim 1 and an automation technology system according to patent claim 14.

[0009] The field device adapter according to the invention for wireless data transmission comprises at least: an adapter housing with a first end and a second end, wherein the first end has a first connection element and a second connection element for electrically connecting to field device electronics of a field device and the second end has a third connection element and a fourth connection element for electrically connecting a two-wire line; adapter electronics arranged in the adapter housing, which connects the first connection element to the third connection element by a first electrical connecting line and the second connection element to the fourth connection element by a second electrical connecting line, wherein the adapter electronics have a preferably unregulated or non-regulated first supply circuit introduced into the first connecting line for providing a first supply voltage from a loop current flowing in the first connecting line and a first supply circuit introduced into the second connecting line,preferably unregulated or non-regulated second supply circuit (15b) for providing a second supply voltage from the loop current flowing in the second connecting line, wherein the adapter electronics further comprises a HART modem which is based on a HART protocol and is connected to the second connecting line at least via a tapping point arranged in the second connecting line, and is configured to tap a two-wire signal modulated onto the loop current and to translate it into a signal, preferably a UART signal and / or to translate a supplied signal, preferably a UART signal, into a two-wire signal and to modulate the translated two-wire signal onto the loop current via the tapping point, wherein the adapter electronics further comprises a radio module with an antenna for transmitting and / or receiving and is configured to transmit the signal translated and supplied by the HART modem,preferably to transmit a UART signal as a radio signal and / or to receive a radio signal which is to be translated into a two-wire signal by the HART modem and to supply it as a signal, preferably a UART signal, to the HART modem, wherein the adapter electronics are designed such that the first supply circuit supplies the HART modem with the first supply voltage and the second supply circuit (15b) supplies the radio module with the second supply voltage, preferably independently of one another.

[0010] According to the invention, a field device adapter is proposed which has two internal supply circuits, one of the two supply circuits supplying energy to a HART modem and the other of the two supply circuits supplying energy to a radio module.

[0011] For example, data can be transferred to a cloud database via the field device adapter. For the purposes of the present invention, a cloud database is understood to be a database that can be accessed by a user via the Internet. The database may include an application, for example, for visualizing the data stored in the database. A user can access the database application and thus the data via the Internet from their device, such as a PC or mobile device.

[0012] It is also possible to operate a "proprietary" field device, which does not actually have a radio module, via the radio adapter connected to the field device.

[0013] An advantageous embodiment of the field device adapter according to the invention provides that the adapter electronics further comprises a galvanic isolation which galvanically separates the HART modem from the radio module and the HART modem and the radio module communicate at least the signal via the galvanic isolation.

[0014] A further advantageous embodiment of the field device adapter according to the invention provides that the HART modem (17) is set up as a primary or secondary master according to the HART protocol.

[0015] A further advantageous embodiment of the field device adapter according to the invention provides that the adapter electronics further comprises at least one communication resistor introduced into the first connecting line between the first supply circuit and the third connection element.

[0016] An alternative embodiment of the field device adapter according to the invention provides that the adapter electronics (14) further comprises at least one communication resistor (18) introduced into the second connecting line (26) between the second supply circuit (15b) and the fourth connection element (11b).

[0017] A further advantageous embodiment of the field device adapter according to the invention provides that the radio module is further configured to transmit the radio signal according to one of the following radio protocols: a Bluetooth protocol or a modified variant thereof, a 6LoWPAN protocol, a WirelessHART protocol, and / or a 6TiSCH protocol to send and / or receive.

[0018] A further advantageous embodiment of the field device adapter according to the invention provides that the adapter electronics further comprises EMC measures which are designed such that at least the first and / or second supply circuit are protected from EMC interference.

[0019] A further advantageous embodiment of the field device adapter according to the invention provides that the adapter electronics further comprise explosion protection measures, wherein the explosion protection measures comprise current-limiting explosion protection measures and / or voltage-limiting measures. In particular, the embodiment can provide that the voltage-limiting measures comprise at least one current shunt regulator, in particular a higher current shunt regulator, which is connected in parallel to the first and / or the second supply circuit and / or that the current-limiting measures comprise at least one resistor connected between the first supply circuit (15a) and the HART modem and / or between the second supply circuit and the radio module.

[0020] A further advantageous embodiment of the field device adapter according to the invention provides that the first end of the adapter housing (7) is further designed such that the first end is a closed end, so that the field device adapter and the field device form two separate mechanical units.

[0021] An alternative embodiment of the field device adapter according to the invention provides that the first end of the adapter housing is further designed such that the field device adapter can be mechanically connected to a field device, preferably a cable gland connection of a field device, particularly preferably to an M20 cable gland connection of the field device, so that the field device adapter and the field device form a mechanically connected unit.

[0022] A further advantageous embodiment of the field device adapter according to the invention provides that the first and / or second supply circuit each has at least one current shunt regulator, in particular a higher current shunt regulator or at least one diode, preferably at least one z-diode, which is designed for a fixed value for the first or second supply voltage.

[0023] The invention further relates to an automation system for detecting and / or setting a process variable, comprising: a first two-wire line for transmitting a loop current with a modulated two-wire signal; a field device of automation technology with a field device housing which has at least one housing opening, wherein the field device further comprises field device electronics arranged within the field device housing, which is configured to communicate data, in particular the process variable, in the form of two-wire signals, in particular two-wire signals based on a HART protocol; a field device adapter according to a previously described embodiment.

[0024] The invention is explained in more detail with reference to the following drawings. It shows: Fig. 1 : a schematic representation of a two-wire field device, as it is currently found in many existing automation systems and with which data can be communicated purely wired via a two-wire line, Fig. 2: a schematic representation of a field device adapter according to the invention, Fig. 3 : a schematic representation of a field device to which a field device adapter is mechanically attached so that the field device and the field device adapter form a mechanically connected unit, and Fig. 4 : a schematic representation of a field device and a field device adapter, each forming a separate unit and electrically connected to each other via a connecting cable.

[0025] Figure 1 shows a schematic diagram of a two-wire field device comprising a metallic housing 2 in which a field device electronics 4 is arranged. The field device electronics 4 is designed in such a way that it has connection terminals 13, via which a two-wire line 12 is electrically connected. Via the two-wire line, the field device electronics 4 and thus the field device 1 are connected to a Fig. 1A higher-level unit 31 (not shown separately) is connected for wired communication with the higher-level unit Data 31. The measured or set values ​​are communicated as the main process variable via the two-wire line 12 in the form of an analog 4-20 mA current signal, and all other data are transmitted in the form of a digital two-wire signal according to the HART standard.

[0026] In order to be able to electrically contact the two-wire cable 12 coming from outside the housing 2 with the field device electronics 4 arranged in the housing 2, the metallic housing 2 has a housing opening 3. A cable gland 5 is introduced into the housing opening 3 so that the two-wire cable 12 can be introduced into the housing 2 through the cable gland 5. The cable gland 5 is preferably designed in the form of a PG cable gland, i.e. a cable gland with a steel armored conduit thread, in accordance with the DIN EN 62444 standard published in May 2014. The cable gland 5 can, for example, be designed as an M20 PG cable gland, i.e. with an outer diameter of 20 mm.

[0027] Fig. 2shows a schematic representation of a field device adapter 6 according to the invention. The field device adapter 6 has an adapter housing 7 with an adapter chamber 10. The adapter housing 7 can be designed such that the field device adapter 6 can be mechanically fastened at a first end 8 to a cable gland 5, in particular a PG cable gland, of a field device 1. For this purpose, the first end 8 of the adapter housing preferably has an M20 thread, via which the adapter can be mechanically screwed to the cable gland of the field device. In particular, the first end 8 can be designed such that it can be connected to a PG cable gland with an M20 thread, in accordance with the DIN EN 62444 standard published in May 2014, of a field device.

[0028] For electrical contacting, the field device adapter 6 has a first and a second connection element 16a and 16b at its first end 8. The first and second connection elements 16a and 16b can each comprise an electrical connection or connecting line for electrical connection to a field device electronics 4. In particular, the connection can be made via a two-wire line 27.

[0029] At a second end 9 opposite the first end 8, the adapter housing 7 is configured such that a two-wire line 12 for data transmission can be electrically connected to the field device adapter 6 via a third and a fourth connection element 11a, 11b. For electrically connecting the two-wire line 12, the third and fourth connection elements 11a and 11b can, for example, comprise a connection terminal.

[0030] Furthermore, the field device adapter 6 has adapter electronics 14 arranged within the adapter chamber, which connects the first connection element 16a to the third connection element 11a via a first electrical connecting line 25 and the second connection element 16b to the fourth connection element 11b via a second electrical connecting line 26. A loop current I is conducted from the two-wire line 12 to the field device electronics 4 via the first electrical connecting line 25, and the loop current I is conducted back to the two-wire line 12 connected to the field device adapter 6 via the second electrical connecting line 26.The adapter electronics 14 are thus configured to communicate digital two-wire signals, which are designed according to the HART standard, in both directions between the two-wire line 12 connected via the third and fourth connection elements and the field device electronics 4 connected via the first and second connection elements 16a 16b.

[0031] For the autonomous power supply of the field device adapter 6, the adapter electronics 14 has a first supply circuit 15a and a second supply circuit 15b, each providing a first and a second supply voltage, respectively. The supply circuits 15a, 15b are preferably designed independently of one another and separated from one another by a galvanic isolation 30. The supply circuits 15a, 15b can each have a Z diode or Zener diode, which are incorporated into the first and second connecting lines in such a way that they are each connected in the reverse direction to the loop current flowing through the first and second connecting lines, respectively, and a voltage tap can be made as a supply voltage across the diode.

[0032] Alternatively, the first and / or second supply circuits 15a and 15b can each have at least one current shunt regulator, in particular a higher current shunt regulator, which are each designed and introduced into the first or second connecting line in such a way that a fixedly adjustable first or second supply voltage is generated.

[0033] The adapter electronics 14 further comprises a radio module 19 with an antenna for transmitting and receiving radio signals and a HART modem 17 for converting / translating the digital two-wire signal. According to the invention, the radio module 19 is supplied with power by one of the two supply circuits, and the HART modem 17 is supplied with power by the other supply circuit. Fig. 2 In the embodiment shown, the first supply circuit 15a supplies the HART modem 17 with the first supply voltage and the second supply circuit 15b supplies the radio module 19 with the second supply voltage.

[0034] The radio module 19 is designed such that, in particular, radio signals can be transmitted according to a Bluetooth protocol or a variant modified therefrom, a 6LoWPAN protocol, a WirelessHART protocol, and / or a 6TiSCH protocol.

[0035] In order to be able to tap the digital two-wire signals communicated on the connected two-wire line 12 or to modulate them onto the loop current I, the adapter electronics 14 has a tapping point 23 introduced into the second connecting line 26. The tapping point 23 is preferably inserted between the second supply circuit 15b introduced into the second connecting line 26 and the fourth connection element 11b. Furthermore, the adapter electronics 14 is designed such that the radio module 19 and the HART modem 17 can communicate data with each other, for example via a UART interface 33. In this way, the radio signals received by the radio module 19 can be transmitted to the HART modem 17 via the UART interface 33 and converted by the HART modem 17 into corresponding digital two-wire signals, which in turn can be modulated onto the loop current via the tapping point 23.Likewise, the digital two-wire signals communicated on the loop current can be tapped by the HART modem at the tapping point 23 and converted by the HART modem 17 into UART signals, which in turn are transmitted via the UART interface 33 to the radio module 19 and transmitted by it as radio signals.

[0036] In order to design the two supply circuits located in the different connecting lines independently of each other, the adapter electronics can have a galvanic isolation via which only the data is communicated between the radio module and the HART modem.

[0037] To enable the adapter electronics 14 to tap the digital two-wire signals via the tap point 23 or to modulate them onto the loop current I, a communication resistor 18 is further provided in the first electrical connecting line 25. The communication resistor 18 can be inserted between the first supply circuit 15a and the third connection element 11a in the first electrical connecting line 25.

[0038] Alternatively, the communication resistor 18 can also be inserted between the second supply circuit and the fourth connection element in the second connecting line 26. In Fig. 2 This is indicated by the dashed resistor. It goes without saying that in this case, there is no communication resistor in the first connecting line 25.

[0039] To enable the adapter electronics 14 to communicate digital two-wire signals to the field device 1, the HART modem 17 is preferably configured as a secondary master. In this way, for example, a field device 1 can be wirelessly parameterized via radio signals received by the radio module 19 of the field device adapter 6 and converted into corresponding digital two-wire signals by the HART modem 17.

[0040] Alternatively, the HART modem 17 can also be configured as the primary master. This can be useful, for example, if only one higher-level unit 31 without a HART communication device and thus no other primary master is present. In this case, the adapter electronics 14 can communicate with the field device electronics 4 via the two-wire cable 27 using HART, for example, to parameterize the field device.

[0041] Additionally, the adapter electronics 14 can have EMC measures 29 designed to protect at least the first and / or second supply circuits 15a, 15b from EMC interference. The EMC measures can, in particular, include one or more suppressor diodes connected in parallel with at least the first and / or second supply circuits. Depending on the connecting line in which the communication resistor is located, the suppressor diode is connected in parallel with the supply circuit located in this supply line and the communication resistor.

[0042] Additionally or alternatively, the adapter electronics 14 can further comprise explosion protection measures 28, 32. These can, in particular, comprise current-limiting explosion protection measures 32 and / or voltage-limiting explosion protection measures 28. For example, the current-limiting explosion protection measures can comprise resistors that are incorporated into a line between the first supply circuit and the HART modem 22a and / or into a line between the second supply circuit and the radio module 22b for the respective voltage supply. The voltage-limiting explosion protection measures can comprise at least one current shunt regulator, in particular a higher current shunt regulator, which is connected in parallel to the first and / or second supply circuit 15a, 15b.

[0043] Fig. 3shows a schematic representation of a field device 1, to which a field device adapter 6 is mechanically attached with its first end 8, so that the field device 1 and the field device adapter 6 form a mechanically connected unit. The field device adapter 6 can, as in Fig. 3 As shown, it can be arranged such that it is located between the housing opening 3 of the field device 1 and the cable gland 5 that actually belongs to the housing opening of the field device. In this case, the adapter housing 7 is designed such that the cable gland 5 can be fastened or screwed onto the correspondingly designed second end 9. For example, the second end 9 can be designed in the form of a PG cable gland with an M20 thread in accordance with the DIN EN 62444 standard published in May 2014.

[0044] Alternatively, the field device adapter 6 can also be designed in such a way that the adapter housing 7 serves as a cable gland and thus a separate cable gland is not required when connecting to the field device 1.

[0045] In both cases, the field device 1 and the field device adapter mechanically attached to the housing opening 3 of the field device 1 form a mechanically connected unit.

[0046] In contrast, Fig. 4a schematic representation of a field device 1 and a field device adapter 6, each forming a separate mechanical unit and electrically connected to each other via a connecting cable, in particular a second two-wire cable 27. Because the field device adapter 6 is only electrically connected to the field device 1 via the connecting cable 27 and not via a mechanical connection, the field device adapter 6 can be flexibly positioned in an automation system, allowing it to be installed virtually independently of the installation location of the field device 1. List of reference symbols

[0047] 1 Field device of automation technology 2 Field device housing 3 Housing opening 4 Field device electronics 5 Cable gland 6 Field device adapter 7 Adapter housing 8 First end of the adapter housing 9 Second end of the adapter housing 10 Adapter chamber 11a Third connection element 11b Fourth connection element 12 (First) two-wire cable 13 Connection terminals of the field device 14 Adapter electronics 15a First supply circuit for powering the HART modem 15b Second supply circuit for powering the radio module 16a First connection element 16b Second connection element 17 HART modem 18 Communication resistor 19 Radio module 20 Mechanical connection element, e.g.M20 thread for mechanically connecting the adapter to a cable gland of a field device 21Bidirectional galvanically isolated data transmission unit 22a, 22bCables for power supply 23Tapping point 25First electrical connecting cable 26Second electrical connecting cable 27Connecting cable, preferably second two-wire cable 28Voltage-limiting explosion protection measures, in particular high current shunt regulators 29EMC measures 30Galvanic isolation 31Higher-level unit, e.g. control system 32Current-limiting explosion protection measures, in particular resistors 33Interface, in particular UART interface ILoop current.

Claims

1. A field device adapter (6) for wireless data transmission, having at least: - One adapter housing (7) with a first end (8) and a second end (9), wherein the first end (8) has a first connecting element (16a) and a second connecting element (16b) for electrically connecting to the field device electronics (4) of a field device (1), and the second end (9) has a third connecting element (11a) and a fourth connecting element (11b) for electrically connecting a two-wire cable (12); - Adapter electronics (14) arranged in the adapter housing (7), which connect the first connecting element (16a) to the third connecting element (11a) through a first electrical connecting cable (25), and the second connecting element (16b) to the fourth connecting element (11b) through a second electrical connecting cable (26), wherein the adapter electronics (14) comprise a preferably unregulated or non-regulated first supply circuit (15a) integrated into the first connecting cable (25) for providing a first supply voltage from a loop current (I) flowing in the first connecting cable (25), and a preferably unregulated or non-regulated second supply circuit (15b) integrated into the second connecting cable (26) for providing a second supply voltage from the loop current (I) flowing in the second connecting cable (25), wherein the adapter electronics (14) further comprise a HART modem (17), which is based on a HART protocol, which is connected to the second connecting cable at least via a tapping point (23) arranged in the second connecting cable, and are adapted to tap a two-wire signal modulated onto the loop current (I) and to translate it into a signal, preferably a UART signal, and / or to translate a supplied signal, preferably a UART signal, into a two-wire signal, and to modulate the translated two-wire signal onto the loop current (I) via the tapping point (23), wherein the adapter electronics further comprise a radio module (19) with an antenna for transmitting and / or receiving and are adapted to transmit the signal translated and supplied by the HART modem (17), preferably a UART signal, as a radio signal and / or to receive a radio signal which is to be translated into a two-wire signal by the HART modem (17) and to supply it as a signal, preferably a UART signal, to the HART modem, wherein the adapter electronics are configured in such a way that the first supply circuit (15a) supplies the HART modem (17) with the first supply voltage and the second supply circuit (15b) supplies the radio module (19) with the second supply voltage, preferably independently of one another.

2. The field device adapter as claimed in the preceding claim, wherein the adapter electronics (14) further comprise a galvanic isolation (30), which galvanically isolates the HART modem (17) from the radio module (19), and the HART modem (17) and the radio module (19) communicate at least the signal, preferably the UART signal, via the galvanic isolation (30).

3. The field device adapter as claimed in one or more of the preceding claims, wherein the HART modem (17) is adapted as a primary or secondary master according to the HART protocol.

4. The field device adapter as claimed in one or more of the preceding claims, wherein the adapter electronics (14) further comprise at least one communication resistor (18) housed in the first connecting cable (25) between the first supply circuit (15a) and the third connecting element (11a).

5. The field device adapter as claimed in one or more of claims 1 to 3, wherein the adapter electronics (14) further comprise at least one communication resistor (18) integrated into the second connecting cable (26) between the second supply circuit (15b) and the fourth connecting element (11b).

6. The field device adapter as claimed in one or more of the preceding claims, wherein the radio module is further adapted to send and / or receive the radio signal according to one of the following radio protocols: - A Bluetooth protocol or a modified version thereof, - A 6LoWPAN protocol, - A WirelessHART protocol, and / or - A 6TiSCH protocol.

7. The field device adapter as claimed in one or more of the preceding claims, wherein the adapter electronics (14) further comprise EMC measures (29) which are configured in such a way that at least the first and / or second supply circuit (15a, 15b) are / is protected against EMC interference.

8. The field device adapter as claimed in one or more of the preceding claims, wherein the adapter electronics (14) further involve explosion protection measures (28, 32), wherein the explosion protection measures comprise current-limiting explosion protection measures (32) and / or voltage-limiting measures (28).

9. The field device adapter as claimed in the preceding claim, wherein the voltage-limiting measures (28) comprise at least one current shunt regulator, in particular a higher current shunt regulator, which is connected in parallel with the first and / or the second supply circuit (15a, 15b).

10. The field device adapter as claimed in either claim 8 or claim 9, wherein the current-limiting measures comprise at least one resistor (32) connected between the first supply circuit (15a) and the HART modem (17) and / or between the second supply circuit and the radio module (19).

11. The field device adapter as claimed in one or more of the preceding claims, wherein the first end (8) of the adapter housing (7) is further configured in such a way that the first end is a closed end, so that the field device adapter (6) and the field device (1) form two wholly separate mechanical units.

12. The field device adapter as claimed in claims 1 to 10, wherein the first end (8) of the adapter housing (7) is further configured in such a way that the field device adapter (6) can be mechanically connected to a field device (1), preferably a cable gland connection (5) on a field device, particularly preferably an M20 cable gland connection on the field device (1), so that the field device adapter (6) and the field device (1) form a mechanically connected unit.

13. The field device adapter as claimed in one or more of the preceding claims, wherein the first and / or second supply circuit (15) each have / has at least one current shunt regulator, in particular a higher current shunt regulator, or at least one diode in each case, preferably at least one zener diode in each case, which is designed to have a fixed value for the first and / or second supply voltage.

14. An automation technology system (1) for detecting and / or setting a process variable, having: - A first two-wire cable (12) for transmitting a loop current (I) with a modulated two-wire signal; - An automation technology field device (1) with a field device housing (2) which has at least one housing opening (3), wherein the field device (1) further comprises field device electronics (4) which are arranged inside the field device housing (2) and are adapted to communicate data, in particular the process variable, in the form of two-wire signals, in particular two-wire signals which are based on a HART protocol; - A field device adapter (6) as claimed in one or more of the preceding claims.