Control unit for field devices with an energy storage device and an associated field device

Abstract

Operating unit for a field device, with an energy storage device (1), a first connection (2), a second connection (3) and a control unit (4), wherein the first connection (2) is suitable for connection to a field device (5) and for supplying power to the latter and the second connection (3) is suitable for connection to a supply unit (6), characterized in that it has an industrial communication interface (7) which is designed to put an industrial communication-capable field device (5) into a power-saving mode in the event of a power failure or undervoltage and to wake it up again therefrom, wherein the field device (5) is supplied from the energy storage device (1) in power-saving mode, and the field device (5) in power-saving mode can be put into a state in which a process value is displayed by a command.

Description

[0001] The invention relates to an operating unit with an energy storage device for a field device from process measurement technology according to claim 1 and an associated field device according to claim 6.

[0002] Field devices are an important component of process automation in industry, where they are used both as optical, inductive, or capacitive proximity switches and in process measurement technology for measuring pressure, temperature, level, or flow rate. Naturally, these measuring points are often distributed in hard-to-reach locations within a plant, with the plant control system communicating with the field devices via fieldbuses and, more recently, via the industrial communication connections described in more detail below.

[0003] Industrial communication is an automated communication system that can integrate both sensors and actuators.

[0004] An industrial communication system operates according to a communication protocol standardized by IEC 61131-9, where it is referred to as SDCI (Single Drop Digital Communication Interface). It consists of a control unit, the industrial communication master, and a field device, known as an industrial communication device. Unlike fieldbuses, this is a point-to-point interface for connecting any sensors or actuators to a control system (PLC) via parallel wiring. Industrial communication systems are now also being used for diagnostics and maintenance planning. Communication is based on the standard 3-wire connection method, so no additional cabling is required.

[0005] Industrial communication is suitable for both binary and analog sensors and actuators. The difference between industrial communication sensors and standard sensors lies in the combination of the standard output channel with an additional data channel. This allows existing connection cables to be used for industrial communication sensors (devices) as well.

[0006] Industrial communication sensors support three types of communication: - Binary, like conventional sensors, - Digital transmission of measured values ​​and - Transmission of device parameters and diagnostic data.

[0007] The applicant's DE 10 2016 221 662 B4 discloses an adapter for controlling a field device via an IO-Link system, wherein the IO-Link system represents an embodiment of the industrial communication systems under consideration that operates according to IEC 61131-9.

[0008] The applicant's patent DE 10 2016 217 706 B4 describes an intermediate unit for the IO-Link system for bidirectional data transmission over longer distances. It consists of a secondary master and a generic (IO-Link) device, whereby the generic device only responds to requests when information from the (sensor) device is available.

[0009] EP 2 256 566 B1 describes a field device with a control unit and a method for controlling it. The control unit is designed to selectively enter a working mode and a sleep mode, wherein the control unit sends a deactivation signal to the monitoring unit before entering sleep mode, and the monitoring unit is designed to return the control unit to working mode after receiving an activation signal.

[0010] EP 3 598 078 A1 teaches how to operate a field device in an energy-saving manner, i.e., to switch off unnecessary consumers. A controlled energy storage system is provided for this purpose.

[0011] EP 3 598 079 A1 discloses a battery-powered field device with an energy storage device connected to a control unit. The field device has loads that are connected to the energy storage device via a controllable switch, so that they can all be de-energized. In one embodiment, only certain components are powered, while others are kept in a sleep mode. Furthermore, a console is proposed that can be connected to the field device for maintenance and software updates. The console can also be configured for connection to the energy storage device and include a power supply suitable for charging a rechargeable energy storage device of the field device.

[0012] DE 10 2018 131 435 A1 discloses a sensor connection element that is associated with a sensor and is designed to transmit energy to the respective sensor and to transmit and receive data to and from the respective sensor. The sensor connection element is further connected to a higher-level control unit via a communication link belonging to the respective sensor connection element and can forward data from the respective sensor to the higher-level control unit, as well as control and regulation data from the higher-level control unit to the respective sensor. The sensor connection element can be designed to be energy self-sufficient with an energy storage device.

[0013] US 2019 / 0235565A1 describes an electronic device and a method for controlling it. The electronic device includes, among other things, a sensor unit, a power source, and a power source management unit designed to send a power-saving mode control command to the sensor unit to put it into a sleep mode.

[0014] Another example of state of the art is DE 10 2018 120 769 A1, which discloses a field device for process automation that is safe and easy to operate.

[0015] One disadvantage of the current state of the art is that, in the event of a power supply failure, the current process value cannot be easily read. Another disadvantage is the lack of an efficient way to manually operate field devices in hard-to-reach locations during a power outage.

[0016] We are looking for a tool that can be used flexibly to support service personnel in the event of a power outage.

[0017] The object of the invention is seen as further improving the state of the art. This should enable service personnel to react more flexibly and efficiently to power supply disruptions. In particular, it should provide a way to manually operate field devices in hard-to-reach locations, for example, to read out the current or last process value.

[0018] This problem is solved according to claims 1 and 6. The dependent claims relate to advantageous embodiments of the arrangements according to the invention.

[0019] The essential inventive concept is to create an operating unit, hereinafter referred to as a power box, which is to be arranged between a field device and its power supply unit, and which is suitable for detecting an undervoltage at the field device and, in the event of a power failure or even just an undervoltage, for putting the field device into a power saving mode and waking it up again, wherein the field device in power saving mode is supplied with power from the power box, and wherein the current (last) process value can be displayed or read out.

[0020] As it turns out, the aforementioned industrial communication connection offers a previously unrealizable possibility of creating a power box with a battery pack and a simple, flexible communication interface to a field device (sensor).

[0021] In a first advantageous embodiment, the power box has an operating button that triggers an industrial communication command for the field device and causes the field device to display a process value, preferably the last or the current one.

[0022] In a second advantageous embodiment, the power box can be configured to query a suitable operating button of the field device and thereby cause the field device to display a desired process value.

[0023] In a third advantageous embodiment, the power box has a display for showing the aforementioned process value.

[0024] It is understood that the use of the power box described above according to the invention requires an industrial communication-capable field device, which must be programmed as desired. In particular, the field device must be configured to enter a power-saving mode (sleep mode) upon receiving an industrial communication command, whereby the field device is placed in a state in which only the components required to display the last process value are supplied with power. The power box can, of course, also be woken up via a power-down command from the field device. In this case, the sensor simply restarts.

[0025] The power box according to the invention essentially consists of a battery pack with an industrial communication-capable interface to the sensor. The power box supplies the connected sensor with power during a power failure or undervoltage and puts it into a power-saving mode. The sensor wakes up from this power-saving mode when the supply voltage is restored. In this case, it returns to its normal state.

[0026] Once power is restored from the higher-level (programmable logic controller, or PLC), a sub-component such as an industrial communication master gateway, or a power supply unit, the time of the outage and the battery charge level are reported to the controller. This allows either maintenance to be initiated or future availability to be predicted.

[0027] In power-saving mode, the display remains dark until a button is pressed. Then it shows the process value for only a few seconds. (Similar to a display off function.)

[0028] This makes maintenance on the machine or industrial plant possible, as the process value can still be reliably displayed even in the event of a power failure.

[0029] Furthermore, the sensor can be activated via a button or a communication command through the power box. This makes it possible to activate a sensor that is difficult or, in extreme cases, completely inaccessible (for example, on a tank).

[0030] This increases operational readiness and reduces the required battery capacity, allowing the use of maintenance-free ultracapacitors (supercapacitors, goldcaps, etc.).

[0031] The invention is explained in more detail with reference to the drawing. Fig. Figure 1 shows a simplified representation of the electronic circuit of the power box. Fig. Figure 2 shows the power box located between a field device and the power supply.

[0032] The Fig. Figure 1 describes a simplified representation of the electronic circuit of the power box.

[0033] It comprises an energy storage device 1, a first connection 2, a second connection 3, and a control unit 4, wherein the first connection 2 serves for connection to a field device 5 and for its power supply, and the second connection 3 serves for connection to a power supply unit 6. Furthermore, an industrial communication interface 7, designated as a communication module, is provided.

[0034] If the supply voltage drops below a threshold (e.g., to 18 V, see industrial communication specification), a regulator (e.g., a boost converter) supplies electrical energy to the field device 5 from a connected energy storage device, battery, or capacitor 1. This ensures the power supply of the field device 5 (not explicitly shown here) during a power outage.

[0035] A unit designated as supply (circuit) ensures the power supply to the control unit 4 (control unit). This unit controls a regulator designated as charge control & converter and the communication interface 7 (communication module).

[0036] In addition, the input voltage is constantly monitored.

[0037] The state of charge of energy storage unit 1 (C1) is also recorded by the control unit and transmitted to an available industrial communication master gateway, PLC, or other higher-level control unit. This allows maintenance to be carried out if necessary, or a possible bridging time to be calculated.

[0038] To charge the energy storage device 1, the charge control contains a suitable charging circuit which replenishes the energy storage device 1 when a power supply is available.

[0039] The industrial communication interface 7 (communication module) establishes a bidirectional connection between the field device 5 and a higher-level controller, such as a PLC. With power supplied, this interface is transparent and simply forwards commands to and from the field device 5. The AUX port can be used to transmit analog signals to and from the connected field device 5.

[0040] In the event of an undervoltage, the power box commands field device 5 to enter sleep mode, thereby reducing its power consumption to a minimum. Nevertheless, instead of operating at the typical cycle time of 0.4 to 132 milliseconds for the IO-Link system considered here, it should activate its specially equipped IO-Link receiver at longer intervals, such as every 3 to 30 seconds, and determine the process value as needed. This significantly increases the time during which a power outage can be bridged. However, this requires an IO-Link receiver that understands IO-Link communication but allows for longer cycle times, because a standard-compliant IO-Link master would report a communication error if the cycle time exceeds 132 milliseconds.

[0041] This requires a software modification of the field device, because IO-Link devices are designed so that if communication breaks down because the master does not adhere to the cycle time, the device remains in communication mode, but error messages may occur. Therefore, a special version is required that does not follow the IO-Link standard and thus allows for a longer cycle time.

[0042] If none of this is desired, a standard field device can also be connected here. In that case, the power box simply serves as a UPS (uninterruptible power supply).

[0043] The Fig. Figure 2 shows the power box located between field device 5 and power supply 6.

[0044] The diagram shows an IO-Link connection, which here acts as an industrial communication link. A higher-level control unit (PLC), not strictly necessary for this explanation, can be connected to the line labeled PLC. It would then function as the master gateway for industrial communication, in this case as the IO-Link master.

[0045] As shown in more detail above, the power box has, in addition to the energy storage unit 1, a first connection 2, a second connection 3, and a control unit 4. The first connection 2 is used to connect to a field device 5 and to supply it with power. The second connection 3 is used to connect to a power supply unit 6, which typically belongs to a higher-level control unit (PLC). Furthermore, an industrial communication interface 7, implemented as IO-Link, is provided for bidirectional communication.

[0046] Furthermore, a control button 8 for manual input of control commands is shown for the control unit and thus also for the field device 5. For example, button 8 can be configured to trigger a measurement cycle on demand.

[0047] In a further embodiment, this can be done automatically according to a time control, e.g. every 2 minutes, whereby the process value (measured value) is always displayed for 30 s, whereby the times can of course be adjusted to the application by parameters.

[0048] A display 9 can serve both to inform service personnel and, according to the invention, to display at least one process value. Reference sign 1 Energy storage 2 First connection 3 Second connection 4 Control unit 5 Field device 6 supply unit 7. Industrial communication interface (e.g. IO-Link interface) 8 operating button 9 Display

Claims

[1] Operating unit for a field device, comprising an energy storage device (1), a first connection (2), a second connection (3) and a control unit (4), wherein the first connection (2) is suitable for connecting to a field device (5) and for supplying it with power, and the second connection (3) is suitable for connecting to a power supply unit (6), characterized by , that it has an industrial communication interface (7) which is configured to put an industrial communication-capable field device (5) into a power-saving mode and wake it up again from it in the event of a power failure or undervoltage, wherein the field device (5) in power-saving mode is supplied from the energy storage device (1), and the field device (5) in power-saving mode can be brought into a state in which a process value is displayed by a command. [2] Control unit according to claim 1, comprising an operating button (8) for triggering an industrial communication command for the field device (5). [3] Control unit according to claim 1, characterized by , that at initial time intervals a process value is always displayed for a second time, whereby these times can be adjusted by parameters. [4] Control unit according to claim 1, configured to query an operating button of the field device (5) and to transmit a trigger command for industrial communication to the field device (5). [5] Control unit according to claim 1 or 2, with a display (9) for displaying a process value of the field device (5). [6] Industrial communication-capable field device (5) configured to enter a power-saving mode upon an industrial communication command generated by an operating unit according to claim 1, wherein the field device (5) is placed in a state in which assemblies required for displaying a process value are supplied with power.

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