Automated field device

Abstract

The invention relates to an automated field device (17) comprising at least: - at least a first, a second and a third connection pin; - a field device electronics (16) designed in such a way that the field device electronics can be operated in a two-conductor mode or in a three-conductor mode. The field device electronics has an energy supply unit (6) which is designed to provide an internal energy supply in the two-conductor mode only by means of a feed current. In the three-conductor mode, an additional auxiliary current will be fed to the field device electronics by means of an additional single-wire line (15c) which will be connected to the third connection pin, and the energy supply unit (6) is also designed for providing the internal energy supply by means of the feed current and the fed additional auxiliary current. Furthermore, the field device electronics (16) is designed to use the additionally fed auxiliary current for the internal energy supply only if the current fed by means of the two-wire line is not sufficient for the internal energy supply.

Description

TECHNICAL FIELD

[0001] The present application relates to automation field devices and automation systems. BACKGROUND

[0002] In automation, field devices for recording and / or modifying process variables are frequently used, in particular in process automation. Sensors, such as fill level measuring devices, flow meters, pressure and temperature measuring devices, pH redox potential meters, conductivity meters, etc., are used to record corresponding process variables, such as fill level, flow rate, pressure, temperature, pH level and conductivity. Actuators, such as, for example, valves or pumps, are used to influence process variables. Thus, the flow rate of a fluid in a pipe section or the fill level in a container can be changed by an actuator. In principle, all devices that are used in a process and supply or process process-related information are referred to as field devices. In the context of the present application, field devices also include remote I / Os, radio adapters and / or devices that are generally arranged on the field level.

[0003] The Endress+Hauser company manufactures and sells various such field devices.

[0004] Due to historical reasons, these are connected to higher-level units, such as PLC control units or control systems, usually via two-wire lines, i.e. lines with two individually formed wires. The two-wire field devices are designed here such that the measurement or control value as process variable is communicated, i.e. transmitted, via the two-wire line in analog form as a 4-20 mA loop current or current signal. In this case, the field device or the higher-level unit sets the loop current of the two-wire line to a specific value depending on the captured process variable. The measurement range is represented linearly on the 4-20 mA current signal.

[0005] In addition, the field devices are also supplied with power via the two-wire line. In this case, the field devices can also be referred to as two-wire line field devices. Typically, a supply voltage between 10-35 V is applied in two-wire line field devices. Thus, with a fault current of < 3.6 mA and a minimum input voltage of, for example, 10 V, a maximum possible supply power of < 36 mW is available for two-wire line field devices.

[0006] Alternatively, if more energy is required than can be provided to the field device via the two-wire line, the field device can also be connected via a three-wire line. This eliminates the need to limit the power supply, as is the case with two-wire lines.

[0007] In order to be able to realize different operating modes (two-wire or three-wire operation), there are different field device electronics integrated into the field device during the manufacture of the field device. This means that the field device manufacturer has to provide different field device electronics or deviations depending on the desired operation. SUMMARY

[0008] It is therefore an object of the present application to provide a reduction in the possibility of manufacturing deviations.

[0009] According to the application, this object is achieved by automating the field device and the automation system.

[0010] The automation field device according to the application comprises at least:

[0011] - at least a first, a second and a third connection pin for connecting the internal field device electronics to an external voltage source;

[0012] - field device electronics which are designed in such a way that they can be operated in a two-wire mode or in a three-wire mode, wherein in the two-wire mode a current is to be fed to the field device electronics via a two-wire line to be connected to the first and second connection pins and the field device electronics have a first data and / or energy supply path which internally guides the current from the first connection pin to the second connection pin, wherein the field device electronics have an energy supply unit which is designed to provide an internal energy supply in the two-wire mode only by the fed current, wherein in the three-wire mode the field device electronics are to be fed an additional auxiliary current via an additional single-wire line to be connected to the third connection pin and the field device electronics have a second energy supply path which internally guides the additional auxiliary current from the first connection pin to the third connection pin, wherein the energy supply unit is also designed to provide an internal energy supply by the fed current and the fed additional auxiliary current, wherein the field device electronics are also designed to use the additionally fed auxiliary current for the internal energy supply only if the current fed via the two-wire line is not sufficient for the internal energy supply.

[0013] According to the application, a field device is proposed which can be operated both in a two-wire mode and in a three-wire mode. This can be achieved by field device electronics which are formed integrally inside the field device and which, depending on the desired operation, can either be contacted only using a two-wire line or, if necessary, additionally using a single-wire line via three outwardly routed connection pins. Since the field device electronics are formed integrally as a combined two-wire and three-wire circuit, deviations of the field device electronics can be reduced, since only one set of field device electronics is required for both operating modes.

[0014] In an advantageous embodiment of the field device according to the application, the field device electronics further has a first and a second diode, wherein the first diode is integrated in the first data and / or energy supply path such that the cathode of the first diode is directed to the electronics supply unit, and wherein the second diode is integrated in the second energy supply path such that the cathode of the second diode is likewise directed to the electronics supply unit, such that the second diode will switch to the conducting state in the event of a voltage applied to the cathode of the first diode falling below a certain voltage value.

[0015] In a further advantageous embodiment of the field device according to the application, the field device electronics further comprises a current isolator which is integrated in the second energy supply path and is designed to provide a potential-free output voltage downstream of the current isolator, and wherein the field device electronics is further designed to feed the potential-free output voltage to the electronics supply unit. In particular, in this embodiment, the field device electronics can further comprise a chopper which is integrated in the second energy supply path and serves to convert a direct voltage applied on the input side into a rectangular alternating voltage applied on the output side, and the field device electronics is further designed to feed the output-side alternating voltage to the current isolator. In particular, in this embodiment, the field device electronics can further comprise a voltage regulator which is connected upstream of the chopper and is designed to regulate the voltage applied via the first and third connection pins.

[0016] In a further advantageous embodiment of the field device according to the application, the field device electronics further comprises a 4-20 mA current regulation unit and is designed such that at least some of the current is directed via the 4-20 mA current regulation unit, wherein the 4-20 mA current regulation unit is configured to set the current according to the 4-20 mA standard in both the two-wire mode and the three-wire mode.

[0017] The application also relates to an automation system comprising at least:

[0018] - an automation field device according to the application;

[0019] - a voltage source arranged outside the field device;

[0020] - a two-wire line which connects the positive pole of the voltage source to the first connection pin by means of a first wire and which connects the negative pole of the voltage source to the second connection pin by means of a second wire.

[0021] In an advantageous embodiment of the system according to the application, an external load resistor is integrated in the connection of the negative pole of the voltage source to the second connection pin.

[0022] A further advantageous embodiment of the system according to the application also comprises a single-wire line connecting the negative pole of the voltage source to the third connection pin. BRIEF DESCRIPTION OF DRAWINGS

[0023] The application is explained in more detail based on the following drawings, in which:

[0024] Figure 1 A field device is shown having field device electronics connected via two connection pins to a voltage source by means of a two-wire line, and

[0025] Figure 2 A field device is shown having field device electronics connected via three connection pins to a voltage source by means of a three-wire line. DETAILED DESCRIPTION

[0026] Figure 1 and 2 The automation field device 17 shown comprises integrated internal field device electronics 16 via which a two-wire or three-wire line can be connected. The field device electronics 16 are thus designed in such a way that the field device 17 can be operated as a two-conductor or three-conductor field device depending on the circumstances or installation situation in the automation system.

[0027] For connecting the field device 17, the field device electronics 16 have at least three connection pins 1, 2, 3 via which a two-wire or three-wire line can be connected. In Figure 1 In the exemplary embodiment shown, the field device has, as an example, four connection pins 1, 2, 3, 4. In addition, the field device electronics comprise an EMC filter 5 connected downstream of the connection pins 1, 2, 3, 4 in order to protect the field device 17 from possible EMC interference, an electronics supply unit 6 for internal energy supply, a microprocessor 7 for internal control of the field device electronics 16, a sensor element or actuator element 8 for capturing or setting a measured or control value, a shunt resistor 9, and a 4-20 mA current regulating unit 10 which sets or modulates a 4-20 mA current signal together with the shunt resistor 9.

[0028] In addition, the field device electronics system 16 can comprise a display and / or input unit 11, for example in the form of a touch display. Via the display and / or input unit 11, for example, a measured or control value can be displayed, or the field device 17 can be parameterized.

[0029] The integrally formed field device electronics 16 according to the present application can be operated in different operating states. On the one hand, the field device electronics 16 can be configured to be operated in a two-conductor mode and, in addition, they can also be configured or have been configured to be operated in a three-conductor mode.

[0030] Figure 1 The two-conductor mode is shown by way of example, in which the field device electronics 16 are connected via the two-conductor line 15 to an external voltage source 19 and an external load resistor 18 in series with the external voltage source 19. In the two-conductor mode, the field device electronics 16 are connected via the first connection pin 1 and the second connection pin 2 to the external voltage source 19 located outside the field device in order to feed a current. In the two-conductor mode, a 4-20 mA current signal for transmitting measurement or control values is communicated via the feeding current and makes possible an internal energy supply for the field device electronics.

[0031] In order to feed the current I fed via the first connection pin 1 to the electronics supply unit 6, the field device electronics have a first data and / or energy supply path 6a (indicated by the thick line in Figure 1 ), which connects the first connection pin 1 via the EMC filter 5 to the electronics supply unit 6. The electronics supply unit 6 is configured to provide an internal energy supply by the feeding current I and to supply energy for other internal electronic components, such as a display and / or input unit 11, a sensor or actuator element 8 and / or a microprocessor 7. In addition, the feeding current I or the part of said current which is not routed via the electronics supply unit to the internal shunt resistor 9 is directed along an additional connection path via a current regulation unit 10 and / or the microprocessor 7.

[0032] The current regulation unit 10 is configured for setting the current in accordance with the 4-20 mA standard. For example, in the case of a field device designed as a sensor, i.e. comprising a sensor element 8, the current via the 4-20 mA current regulation unit 10 together with the shunt resistor 9 can be set in accordance with a process variable captured by the sensor element in order to be transmitted to a higher-level unit (not shown in Figure 1 In order to enable the two-conductor mode, a switching unit 14 is provided, which is configured to direct the current I from the shunt resistor 9 via the 4-20 mA output path 9 to the second connection pin 2.

[0033] Figure 2A three-conductor mode is shown by way of example, in which the field device electronics 16 is connected to the negative pole of the external voltage source 19 via an additional single-wire line 15c. Here, the additional single-wire line 15c is connected via a third connection pin 3 of the field device electronics 16. Via the additional single-wire line 15c, energy can additionally be fed to the field device electronics 16 via the first and third connection pins 1, 3.

[0034] According to the application, the field device electronics 16 is designed to provide additional energy available between the first and third connection pins 1, 3, depending on the requirements of the other internal electronic components of the field device electronics, if the energy that can be generated by the feed current is not sufficient for the internal energy supply.

[0035] Since the negative pole of the voltage source is additionally connected to the third connection pin by a single-wire line, additional current can be provided to the field device electronics to generate energy. The field device electronics is designed such that the additional current is rectified via a second energy path 6b (indicated by a thick line in Figure 2

[0036] However, when the additional single-wire line 15c is connected between the third connection pin 3 and the negative pole of the external voltage source 19, since the third connection pin is at a lower voltage or potential than the second terminal pin connected to ground, the field device electronics will also include a current isolator 13 integrated in the second energy path, so that the output voltage downstream of the current isolator is not grounded or potential-free and can be fed to the electronics supply unit 6 connected to the ground of the field device electronics 16 for internal energy supply. The voltage or potential difference between the second and third connection pins can also fluctuate as a function of the external load resistor 18 and / or the current set by the 4-20 mA current regulation unit 10.

[0037] In addition, the field device electronics comprises a chopper 23 for converting a direct voltage applied on the input side into a rectangular alternating voltage applied on the output side, so that the output side alternating voltage can subsequently be converted via the current isolator 13,

[0038] The chopper 23, the rectifier 20 and the current isolator 13 can either be implemented as separate electronic components or in a single electronic component.

[0039] ​Optionally, the field device electronics system 16 can also have a voltage regulator 12, which is connected upstream of the chopper 23 and is designed to stabilize the voltage applied via the first and third connection pins 1, 3, such that the voltage can be fed to the electronics supply unit 6 for the energy supply.

[0040] In order to be able to use additional energy as required, i.e. only when the energy obtained from the current fed via the two-wire line or the stabilized voltage U is not sufficient to supply the internal components with sufficient energy, the field device electronics Fig. 16 comprises a diode arrangement. The diode arrangement consists of a first diode 21a, which is integrated in the first data and / or energy supply path 6a, such that the cathode of the first diode 21a is directed to the electronics supply unit 6, and a second diode 21b, which is integrated in the second energy supply path 6b, such that the cathode of the second diode 21b is also directed to the electronics supply unit 6, such that in the event of a drop in the stabilized voltage U applied to the cathode of the first diode below a certain voltage value Usp, the second diode 21b will switch to the conducting state. In this case, the certain voltage value Usp depends on the design or size of the field device electronics 16 and is essentially defined by the voltage U stabilized by the voltage regulator 12, wherein the certain voltage value Usp is selected to be greater than the stabilized voltage U, i.e. Usp > U. Typically, the certain voltage value Usp is greater than the stabilized voltage U by the forward voltage of the second diode. For example, the field device electronics can be dimensioned such that the stabilized voltage U provided as operating voltage for the voltage stabilizer of the electronics supply unit 6 is approximately 15 V and the certain voltage value is approximately 15.7 V, wherein the second diode has a forward voltage of approximately 0.7 V. The advantage of this demand-dependent activation supply is that the heat development of the field device electronics can be reduced during operation using an active current output.

[0041] Furthermore, the field device electronics can have a fourth connection pin 4, in particular for communication purposes. For example, the field device electronics can be designed such that digital communication, in particular IO-Link communication, is available via the fourth connection pin 4.

[0042] List of reference signs

[0043] 1 first connection pin

[0044] 2 second connection pin

[0045] 3 third connection pin

[0046] 4 fourth connection pin

[0047] 5 EMC filter

[0048] 6 electronics supply unit

[0049] 6a first data and / or energy supply path

[0050] 6b second energy supply path

[0051] 7 microprocessor

[0052] 8 sensor or actuator element

[0053] 9 internal shunt resistor

[0054] 9a 4-20 mA output path

[0055] 10 4-20 mA current regulation unit

[0056] 11 display and / or output unit

[0057] 12 voltage regulator

[0058] 13 current isolator

[0059] 14 switching unit

[0060] 15 two-wire line

[0061] 15a first conductor of the two-wire line

[0062] 15b second conductor of the two-wire line

[0063] 15c additional single-wire line

[0064] 16 field device electronics

[0065] 17 automated field device

[0066] 18 external load resistor

[0067] 19 external voltage source

[0068] 20 rectifier

[0069] 21a first diode

[0070] 21b second diode 21a

[0071] 22 connection path

[0072] 23 chopper

[0073] U stable voltage

[0074] Usp specific voltage value

Claims

1. An automated field device (17), comprising at least: - At least a first, second and third connection pins, said at least a first, second and third connection pins are used to connect internal field device electronics to an external voltage source (19). - The field device electronics (16) are designed to operate in either a two-conductor or three-conductor mode, wherein in the two-conductor mode, current is fed to the field device electronics via a two-wire line (15) to be connected to the first and second connection pins (1, 2), and the field device electronics (16) has a first data and / or power supply path (6a) that internally guides the current from the first connection pin to the second connection pin, wherein the field device electronics has an electronics supply unit (6) designed to provide internal power solely through the fed current in the two-conductor mode. In the three-conductor mode, the field device electronics (16) will be fed an additional auxiliary current via an additional single-wire line (15c) to be connected to the third connection pin, and the field device electronics (16) has a second power supply path (6b) that internally guides the additional auxiliary current from the first connection pin to the third connection pin. The electronic device supply unit (6) is also designed to provide the internal power supply via the fed current and the fed additional auxiliary current. The field device electronics (16) is also designed to use the additional auxiliary current for the internal power supply only when the current fed via the two-wire line is insufficient for the internal power supply.

2. The automated field device according to claim 1, wherein, The field device electronics further includes first and second diodes (21a, 21b), wherein the first diode is integrated in the first data and / or power supply path (6a) such that the cathode of the first diode is directed to the electronic device supply unit (6), and wherein the second diode is integrated in the second power supply path (6b) such that the cathode of the second diode (21b) is also directed to the electronic device supply unit (6), such that when the voltage applied to the cathode of the first diode (21a) drops below a certain voltage value, the second diode (21b) will switch to a conducting state.

3. The automated field device according to claim 1, wherein, The field device electronics further includes a current isolator (13) integrated in the second power supply path (6b) and designed to provide a potential-free output voltage downstream of the current isolator (13), wherein the field device electronics (16) is further designed to feed the potential-free output voltage to the electronics supply unit (6).

4. The automated field device according to claim 3, wherein, The field device electronics (16) further includes a chopper (23) integrated in the second power supply path (6b) and used to convert a DC voltage applied to the input side into a rectangular AC voltage applied to the output side, and the field device electronics (16) is further designed to feed the output AC voltage to the current isolator (13).

5. The automated field device according to claim 4, wherein, The field device electronics (16) further includes a voltage regulator (12) connected upstream of the chopper (23) and designed to regulate the voltage applied via the first and third connection pins (1, 3).

6. The automated field device according to any one of claims 1-5, wherein, The field device electronics (16) further includes a 4-20mA current regulation unit (10) and is designed such that at least some of the currents are guided via the 4-20mA current regulation unit (10), wherein the 4-20mA current regulation unit (10) is configured to set the current according to a 4-20mA standard in both two-wire and three-wire modes.

7. An automated system, comprising at least: - The automated field device according to any one of claims 1-6; - An external voltage source (19) located outside the field device; - A two-wire line (15) connects the positive terminal of the external voltage source to the first connection pin (1) via a first wire (15a) and connects the negative terminal of the external voltage source (19) to the second connection pin (2) via a second wire (15b).

8. The automation system according to claim 7, wherein, An external load resistor (18) is integrated into the connection between the negative terminal of the external voltage source (19) and the second connection pin (2).

9. The automation system according to claim 7 or 8, further comprising an additional single-wire line (15c) connecting the negative terminal of the external voltage source (19) to the third connection pin (3).

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