DEVICE AND METHOD FOR CONNECTING A FIELD DEVICE TO A COMMUNICATION SYSTEM

Description

[0001] The invention relates to a device and a method for connecting a field device to a communication system.

[0002] Currently, analog field devices, for example in process engineering, are often operated with a HART interface. Communication via the HART interface serves to configure the field devices, as well as for diagnostics and the transmission of additional information. Establishing and terminating communication with the field devices and exchanging data can be accomplished via a point-to-point connection using a HART modem and a PC. Furthermore, communication can be achieved via distributed I / O devices that provide analog modules with HART controllers and act as HART multiplexers.

[0003] Communication via the HART protocol is slow compared to more modern Ethernet-based solutions and is rather unsuitable for the permanent exchange of large amounts of data.

[0004] A bus physics protocol was developed that offers the advantages of HART while simultaneously meeting the requirements for fast data transmission of large data volumes. Similar to the HART protocol, the so-called Advanced Physical Layer (APL) uses a 2-wire interface for communication with the field device and for power supply. Data transmission in APL is carried out using Ethernet-based protocols.

[0005] A large proportion of currently available field devices, especially sensors and / or actuators, use the HART protocol for configuration and parameterization, as well as for transmitting additional device information. For example, so-called dynamic variables are transmitted, such as device temperature or medium temperature in a flow measurement. Dynamic variables are transmitted approximately twice per second. The main measured value of a sensor or the setpoint of an actuator is represented by the standardized 4-20 mA current signal as an analog signal on a 2-wire interface, achieving a refresh time of approximately 20 ms.

[0006] The HART protocol provides, in particular, an FSK procedure. (Frequency Shift Keying).A signal is modulated onto the 2-wire measurement signal of 4–20 mA. A transmitter power isolator can provide the necessary energy to power the field devices (so-called active input). The measurement signal then consists of the current draw of the field device in the range of 4–20 mA. If the power requirement cannot be supplied by an active input, such field devices are powered by a separate auxiliary power supply. The 4–20 mA measurement signal is generated directly by the field device, which is connected to a so-called passive input for further processing.

[0007] Communication via APL is primarily carried out using Ethernet-based protocols and differs significantly from the HART protocol, which is based on a completely differently designed physical layer.

[0008] In practice, the challenge is that the renewal of existing systems and the conversion to Ethernet-based communication will take a long time, and that in the meantime, different technologies will have to be used side by side.

[0009] WO 2021 / 152010 A1 discloses an SPE-based device adapter for connecting a non-Ethernet-enabled field device to an Ethernet-based process control system. US 10,432,412 B2 describes a configurable interface for a process control device. US 10,296,483 B2 discloses a fieldbus network. DE 10 2017 07 535 A1 describes a Power over Ethernet -based field device. A device for providing an adaptive fieldbus connection is known from US 2005 / 228509 A1.

[0010] The object of the invention is therefore to provide a device and a method for connecting a field device to a communication system that allows maximum compatibility with different components.

[0011] This problem is solved by a device and a method of the type mentioned above, comprising the features of the independent claims. Advantageous embodiments and further developments of the invention are specified in the dependent claims.

[0012] The device for connecting a field device to a communication system comprises a field device interface for connecting the field device, a communication interface for connecting to the communication system, at least one protocol conversion unit, and a switching unit. The switching unit is configured to detect the protocol used by the field device upon connection and, depending on the detected protocol, to establish a connection between the connected field device and the communication interface via the protocol conversion unit.

[0013] Furthermore, depending on the detected protocol, the connection between the connected field device and the communication interface can also be established directly, bypassing the protocol conversion unit.

[0014] The connected field device can be designed in a known manner and may, for example, include a sensor and / or an actuator. A sensor detects a measured value and makes it available via a data interface, while an actuator is configured to receive a control signal and adjust accordingly.

[0015] The protocol conversion unit can be coupled to the communication interface. For example, the protocol conversion unit is located between the switching unit and the communication interface of the device.

[0016] The protocol conversion unit is designed to handle communication with the field device via a protocol used by the field device and to connect this communication with the communication system via a different protocol. This means that communication is enabled between the communication system and the field device, even though they use different protocols.

[0017] The switching unit detects which protocol the connected field device uses and establishes a data connection between the field device and the switching unit accordingly. Specifically, if the field device uses a protocol compatible with the communication system, a data connection is established without requiring any protocol conversion.

[0018] This means that the switching unit is specifically designed to switch between different indirect and / or direct data connections between the field device and the communication system.

[0019] The device is designed to be connected to the communication system via the communication interface and to conduct communication via the communication system. In particular, the field device can therefore be connected to the communication system regardless of the direct compatibility of the protocols used, and it can be integrated into a larger system, such as a system of field devices and control systems.

[0020] The communication system includes a bus system, namely an Ethernet-based bus system.

[0021] This advantageously allows the field device to be connected to a bus system. Common bus systems enable good data transmission with high speed and large data volumes.

[0022] Various, inherently familiar bus systems can be used. In particular, the bus system uses an Ethernet-based standard for communication. For example, the communication system can be designed as a fieldbus.

[0023] Furthermore, according to the invention, the switching unit is configured to establish a connection between the connected field device and the protocol conversion unit if the protocol used by the connected field device is a HART protocol. The protocol conversion unit also includes a HART master device.

[0024] This advantageously allows a HART-compatible field device to be connected to a communication system, regardless of the protocol used by the latter. In particular, a connection to an Ethernet-compatible bus system is possible. The communication system can therefore be used with an Ethernet-compatible protocol, even if not all field devices are adapted to this communication protocol.

[0025] During further training, if the protocol used by the connected field device is a HART protocol, a current loop to supply the field device with 4 - 20 mA can be activated.

[0026] This advantageously enables the field device to operate even if the communication system uses other protocols incompatible with the HART protocol. The necessary power supply can be provided by the device in this case, even if other comparable facilities are unavailable. In particular, this can be provided by a HART master device integrated into the device.

[0027] Furthermore, according to the invention, the switching unit is configured to establish a direct connection between the connected field device and the communication interface if the transmission physics used by the connected field device complies with the APL standard and uses an Ethernet-based protocol.

[0028] This advantageously allows APL-compatible field devices to be used directly with the device and connected to the communication system. The device can then be operated like a conventional switch. In particular, no conversion is required between an Ethernet-compatible communication system and the APL-compatible field device, as the latter is also Ethernet-compatible.

[0029] Further training includes setting up the field device interface for connecting multiple field devices. These field devices can use different protocols.

[0030] This allows the device to be advantageously used to combine the communication links to various field devices and connect them to the communication system.

[0031] In particular, it may be provided that several connections of the device are combined in a peripheral module, which is connected to a communication module. In this case, the device comprises the two modules, to which one or more field devices can be connected on the peripheral module side and to which the communication system can be connected on the communication module side. Specifically, a communication module is provided for each connection of the peripheral module; if there are a large number of connections for field devices, then an equally large number of communication modules can be provided, each assigned to a connection and combined in a higher-level module.

[0032] In particular, a remote I / O system can be implemented. In this system, one or more devices can be connected to an internal module bus via communication modules, with the module bus being coupled to the communication system via a downstream gateway. This advantageously allows several devices configured as remote I / O modules to be interconnected so that they are connected to the communication system via a common interface.

[0033] During further training, the switching unit is configured to first perform a connection detection according to the Ethernet standard when the protocol used by the field device is detected, and if no Ethernet-based protocol is detected, then to attempt a connection using the HART protocol.

[0034] This advantageously ensures that the possibility of a lower-voltage data connection via an Ethernet protocol is checked first, before the higher voltage values ​​of a connection according to the HART protocol are tested. In this way, damage to communication components due to overload and impermissible maximum values ​​can be avoided.

[0035] The process for connecting a field device to a communication system involves detecting the protocol used by the field device upon connection. Depending on the detected protocol, a connection is then established between the connected field device and the communication system, enabling protocol translation.

[0036] The method is specifically designed to operate the device. It therefore has the same advantages as the device according to the invention.

[0037] The invention is explained in more detail below with reference to the accompanying drawings. These show: Figure 1A an exemplary embodiment of the device; Figure 1B another embodiment of the device as a module in a remote I / O system; Figure 1C another embodiment of the device as a standalone solution; Figure 1D a detailed view of a peripheral module of the device; and Figure 2 an embodiment of the method.

[0038] With reference to Figure 1A An exemplary embodiment of the device is explained.

[0039] In this embodiment, the device 10 comprises a plurality of communication modules. 11 as well as a peripheral module 12.

[0040] In further embodiments, at least one communication module 11 is provided.

[0041] The communication modules are included. 11 essentially the same structure.

[0042] The peripheral module 12 and the communication modules 11 are linked together.

[0043] In the embodiment, the peripheral module 12 has field device interfaces 12a, 12b, 12c, 12d, which are designed in particular as ports or connections for field devices 20a, 20b, 20c.

[0044] In this embodiment, ports 12a, 12b, 12c, 12d are essentially identical in design.

[0045] Ports 12a, 12b, 12c, 12d are each coupled to one of the communication modules 11.

[0046] In particular, a coupling via three lines is provided between each communication module 11 and a port 12a, 12b, 12c, 12d, as shown in the present Figures 1A to 1D however, they are only shown schematically.

[0047] The peripheral module 12 limits the applied voltage to the value required for the field device and modulates the corresponding communication signal.

[0048] Further details of Peripheral Module 12 are below with reference to Figure 1D explained.

[0049] In the case shown here, the field device interfaces 12a, 12b, 12c, 12d are configured to be connected to the field devices 20a, 20b, 20c via a wired connection. In particular, an electrical connection is established that can be used to transmit data.

[0050] If necessary, the connection between the field device interfaces 12a, 12b, 12c, 12d can also be used to transmit electrical energy, in particular to provide an operating voltage for a field device 20a, 20b, 20c and / or a measuring device of the field device 20a, 20b, 20c.

[0051] In another embodiment, at least one field device interface 12a, 12b, 12c, 12d is configured to establish a wireless connection to a field device 20a, 20b, 20c, in particular via radio.

[0052] In this example, each of the communication modules 11 includes a switching unit 14. This is coupled to a HART master device 16, which in turn is coupled to a protocol conversion unit 18.

[0053] Furthermore, in the embodiment, the protocol conversion unit 18 is coupled with a communication interface 19, which here is designed as an Ethernet switch 19.

[0054] In addition, in this embodiment the switching unit 14 is also directly coupled to the communication interface 19.

[0055] In the case shown, several field device interfaces 12a, 12b, 12c, 12d are provided. Here, the protocol conversion units 18 and switching units 14 are coupled to the communication interface 19.

[0056] In another embodiment, the communication module 11 can be designed as an independent unit that already has a communication interface 19. An example of such a configuration is given below with reference to Figure 1C explained in more detail.

[0057] The device 19 is coupled to the communication system 30 via the communication interface 19, which in this example is designed as an Ethernet-compatible bus system 30.

[0058] With reference to Figure 1BAnother embodiment of the device as a module in a remote I / O system is explained. This explanation is based on the embodiment of the device described above. Functionally or structurally identical or comparable elements are designated with the same reference numerals.

[0059] The system shown here as an example has several devices 10 that are essentially analogous in design. They may differ, for example, in the number of communication modules 11 and / or ports 12a, 12b, 12c, 12d provided.

[0060] The devices 10 are designed as remote I / O modules.

[0061] The devices 10 are coupled to a remote I / O gateway 22 via their communication interface 19.

[0062] In particular, it may be provided that the communication interfaces 19 of the devices 10 or of the remote I / O modules are connected to an internal module bus, to which the remote I / O gateway 22 is connected.

[0063] Communication with the bus system 30 takes place via the remote I / O gateway 22.

[0064] The remote I / O system allows for the provision of a large number of field device interfaces 12a, 12b, 12c, 12d and their flexible distribution across the field. This enables, for example, centralized control and monitoring of field devices 20a, 20b, 20c, even if they are widely dispersed.

[0065] In another embodiment, it can be provided that instead of a plurality, only one device 10 is coupled to the bus system 30 as a single remote I / O module via the remote I / O gateway 22.

[0066] With reference to Figure 1CAnother embodiment of the device is explained as a separate solution. This embodiment is also based on the embodiment of the device described above. Functionally or structurally identical or comparable elements are identified by the same reference numerals.

[0067] In this embodiment, the device 10 has only one communication module 11 and only one peripheral module 12. Accordingly, a port 12a is provided to which a field device 20a can be connected.

[0068] The communication module 11 is structured as described above. It comprises a switching unit 14, a HART master device 16, a protocol conversion unit 18, and a communication interface 19.

[0069] The device 10 is coupled to the bus system 30 via the communication interface 19.

[0070] With reference to Figure 1DA detailed view of a peripheral module of the device is explained. The exemplary embodiments of the device and the peripheral modules 12 described above are used as a basis. Functionally or structurally identical or comparable elements are identified by the same reference numerals.

[0071] In this example, the peripheral module 12 includes a voltage limiter 24 and a modulation unit 26.

[0072] The peripheral module 12 is shown here with only one port to a field device 20a, 20b, 20c (not shown in the figure).

[0073] In this example, the peripheral module 12 is coupled to the communication module 11 (not shown in the figure) via three lines 28a, 28b, 28c, which are shown schematically.

[0074] One of the lines 28a is connected to a voltage limiter 24. The voltage limiter 24 is designed to reduce the voltage applied via line 28a to a value required for the connected field device 20a, 20b, 20c, or to prevent excessively high voltage values.

[0075] The voltage limiter is in turn coupled to the modulation unit 26.

[0076] The modulation unit 26 is coupled to the communication module 11 via two lines 28b, 28c.

[0077] The modulation unit 26 is designed to receive a communication signal and modulate it onto a supplied voltage.

[0078] In further embodiments, the peripheral module 12 is provided to be connectable to field devices 20a, 20b, 20c via several ports 12a, 12b, 12c, 12d. In this case, a separate voltage limiter 24 and a separate modulation unit 26 are provided for each port 12a, 12b, 12c, 12d.

[0079] With reference to Figure 2 An exemplary embodiment of the method is explained. This is based on the exemplary embodiment of the device described above, which is further specified below.

[0080] In a first step 42, a field device 20a, 20b, 20c is connected to one of the field device interfaces 12a, 12b, 12c, 12d of the device 10. The connection is detected by the current consumption of the field device and a process is started to detect the protocol used by the connected field device 20a, 20b, 20c.

[0081] Furthermore, this step 42 can also be performed when a field device 20a, 20b, 20c connected to a field device interface 12a, 12b, 12c, 12d is restarted or initiated.

[0082] In the exemplary embodiment, the protocol detection is performed in a further step 44. In this example, the device 10 is suitable for connecting field devices 20a, 20b, 20c that communicate according to the HART protocol or via an Ethernet-compatible protocol.

[0083] First, it is checked whether the connected field device 20a, 20b, 20c communicates via the Ethernet protocol. For this purpose, the voltage limiter 24 is set to the voltage limit typical for APL and a standard signal is modulated onto it.

[0084] If Ethernet-compliant communication behavior of the connected field device 20a, 20b, 20c is obtained, then in step 46 a direct connection is established from the switching unit 14 to the communication interface 19. That is, in this case, the port 12a, 12b, 12c, 12d, to which the field device 20a, 20b, 20c is connected, is configured with parameters relevant for APL devices regarding power supply and data exchange, and a connection is established between the respective port 12a, 12b, 12c, 12d and the communication system 30.

[0085] If no Ethernet-compatible connection is detected, the system then checks whether the connected field device 20a, 20b, 20c can be addressed via communication compatible with the HART protocol. For this purpose, the HART master device 16 is used, which attempts to address the connected field device 20a, 20b, 20c as a HART slave device via the modulation unit 26. Port 12a, 12b, 12c, 12d is configured with the current loop parameters required for HART field devices, and a connection is established between port 12a, 12b, 12c, 12d and the HART master device 16. The HART master device 16 then attempts to establish communication with the field device according to HART communication conventions.

[0086] If HART communication is possible, the protocol conversion unit 18 activates the connection to the communication system 30 in step 48. The connected HART field device 20a, 20b, 20c can then communicate via HART-IP.

[0087] The protocol implementation unit 18 takes on the task of providing an APL or Ethernet-compliant communication interface to the communication system 30 and implementing it in such a way that HART-compliant communication between the HART master device 16 and the field device 20a, 20b, 20c takes place.

[0088] A key idea of ​​the invention is to provide an interface that supports various protocols, in particular HART and APL. Depending on which protocol a connected field device 20a, 20b, 20c uses, the interface supplies the field device 20a, 20b, 20c via a NAMUR-compliant 4-20 mA current loop and performs communication according to the HART protocol, or it is operated with a voltage defined for APL spurs and allows Ethernet-based communication.

[0089] This interface can be implemented, for example, as part of a switch or as a module of a remote I / O system. If, for instance, an APL field device is detected, it communicates via the Ethernet protocols associated with field device 20a, 20b, 20c in the network. When a HART field device is connected, however, the 4-20 mA current loop required to power field device 20a, 20b, 20c is activated, and a HART master device takes over communication with field device 20a, 20b, 20c.

[0090] The invention can then be implemented, for example, in a managed switch.

[0091] In another example, the device may be operated as a module of a remote I / O system.

[0092] In existing Ethernet networks, field devices 20a, 20b, 20c can transmit additional variables, diagnostic data and other data via HART-IP communication.

[0093] In one embodiment, a unit 10 is provided, consisting of a communication part 11 and a peripheral part 12. This unit 10 connects the connected field devices 20a, 20b, 20c to a higher-level communication system 30. Each APL and HART field device 20a, 20b, 20c has access to a common port 12a, 12b, 12c, 12d, meaning that field devices 20a, 20b, 20c for different protocols can be connected to the same port 12a, 12b, 12c, 12d. The port 12a, 12b, 12c, 12d is connected to a port identifier of the unit 10, which establishes the connection to a HART master device 16 or to the Ethernet switch 19, depending on the type of field device communication.

[0094] The connection detection initially controls the voltage limiter 24 with the voltage values ​​typical for APL devices. These are generally below those of 4-20 mA HART field devices. The communication behavior of the field device 20a, 20b, 20c is then checked: If this is consistent with the behavior of Ethernet-based communication, the port 12a, 12b, 12c, 12d is configured with the parameters relevant for APL devices regarding power supply and data exchange. After successful connection detection, a connection stage establishes a connection between the port 12a, 12b, 12c, 12d and the higher-level communication unit 30.

[0095] If no Ethernet-based communication is detected, ports 12a, 12b, 12c, and 12d are configured with the current loop parameters required for HART field devices. The port detection unit establishes a connection between ports 12a, 12b, 12c, and 12d and the HART master device 16 via the modulation unit 26. The HART master device 16 then attempts to establish communication with the field device 20a, 20b, and 20c according to the conventions of the HART protocol. If HART-compliant communication is possible, the protocol conversion unit activates the connection to the higher-level communication system 30, thereby transforming the connected HART field device 20a, 20b, and 20c into a HART IP device.

[0096] The field device 20a, 20b, 20c can now establish communication with the higher-level communication system 30 and receive and send data. The power supply of the field device 20a, 20b, 20c is also adjusted depending on the HART, APL, or Ethernet protocol used.

[0097] This also offers economic advantages: Existing systems undergoing modernization typically contain a large number of 4-20 mA HART devices. Due to their proven reliability, these devices are generally not replaced during modernization unless there is an immediate need. However, if digitalization is the primary focus, devices with a particular emphasis on information provision can be converted to APL by replacing their electronics. A multiport device that supports both HART and APL allows for the parallel operation of both communication methods, even without installing the APL infrastructure required for APL field devices to connect to all field devices. Reference symbol list

[0098] 10 Device 11 Communication module 12 Peripheral module 12a, 12b, 12c, 12d Field device interface; port; connection 14 Switching unit 16 HART master device 18 Protocol conversion unit 19 Communication interface; Ethernet switch 20a, 20b, 20c Field device 22 Remote I / O gateway 24 Voltage limiter 26 Modulation unit 28a 28b, 28c Line 30 Communication system; bus system 42, 44, 46, 48 Step

Claims

1. Apparatus (10) for connecting a field device (20a, 20b, 20c) to a communication system (30), comprising a field-device interface (12a, 12b, 12c, 12d) for connecting the field device (20a, 20b, 20c); a communication interface (19) for connecting to the communication system (30); a protocol conversion unit (18); and a switching unit (14); wherein the switching unit (14) is set up to, when the field device (20a, 20b, 20c) is connected, detect a protocol used by the field device (20a, 20b, 20c) and, depending on the detected protocol, establish a connection between the connected field device (20a, 20b, 20c) and the communication interface (19) via the protocol conversion unit (18); characterized in that the communication system (30) comprises an Ethernet-based bus system; and the switching unit (14) is set up to, if the protocol used by the connected field device (20a, 20b, 20c) is a HART protocol, establish a connection between the connected field device (20a, 20b, 20c) and the protocol conversion unit (18); wherein the protocol conversion unit (18) further comprises a HART master device (16), wherein the switching unit (14) is further set up to, if the connected field device (20a, 20b, 20c) uses transmission physics corresponding to the APL standard, establish a direct connection between the connected field device (20a, 20b, 20c) and the communication interface (19).

2. Apparatus (10) according to Claim 1, characterized in that, if the protocol used by the connected field device (20a, 20b, 20c) is a HART protocol, a NAMUR-compliant current loop for supplying the field device (20a, 20b, 20c) with 4-20 mA is able to be activated.

3. Apparatus (10) according to either of the preceding claims, characterized in that the field-device interface (12a, 12b, 12c, 12c) is set up to connect a plurality of field devices (20a, 20b, 20c, 20d); wherein the field devices (20a, 20b, 20c, 20d) can use different protocols.

4. Apparatus (10) according to one of the preceding claims, characterized in that the switching unit (14) is set up to, when detecting the protocol used by the field device (20a, 20b, 20c, 20d), first of all perform a connection detection according to the Ethernet standard and, if no Ethernet-based protocol has been detected, subsequently perform a connection attempt by means of HART protocol.

5. Method for connecting a field device (20a, 20b, 20c, 20d) to a communication system (30), wherein, when the field device (20a, 20b, 20c, 20d) is connected, detection of a protocol used by the field device (20a, 20b, 20c, 20d) is performed; wherein, depending on the detected protocol, a connection between the connected field device (20a, 20b, 20c, 20d) and the communication system (30) is established such that a protocol conversion is performed; characterized in that the communication system (30) comprises an Ethernet-based bus system; and, if the protocol used by the connected field device (20a, 20b, 20c) is a HART protocol, a connection is established between the connected field device (20a, 20b, 20c) and a protocol conversion unit (18) for performing the protocol conversion; wherein the protocol conversion unit (19) further comprises a HART master device (16), wherein, in the method, if the connected field device (20a, 20b, 20c) uses transmission physics corresponding to the APL standard, a direct connection is established between the connected field device (20a, 20b, 20c) and a communication interface (19) which is configured for connecting to the communication system (30).