DE102020134408A1 - Operating unit for field devices with an energy store and an associated field device - Google Patents

Abstract

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

Description

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

Field devices are an important part of process automation in industry, where they are used on the one hand as optical, inductive or capacitive proximity switches, and on the other hand in process measurement technology to measure pressure, temperature, level or flow. Naturally, these measuring points in a plant are often distributed at locations in the field that are difficult to access, with the plant control communicating with the field devices via fieldbuses and recently also via the industrial communication connections described in more detail below.

Industrial communication is an automated communication system in which both sensors and actuators can be integrated.

An industrial communication system works according to a communication standardized by the standard (IEC 61131-9) and is referred to there as SDCI (single drop digital communication interface). It consists of a control unit, the industrial communication master, and a field device known as the industrial communication device. In contrast to field buses, this is a point-to-point interface for connecting any sensors or actuators to a control system (PLC) via parallel wiring. Recently, industrial communication systems have also been used for diagnosis and maintenance planning. Communication is based on the usual 3-wire connection method. Additional cable material is therefore not required.

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. Existing connecting cables can also be used for industrial communication sensors (devices).

• - Binär, wie herkömmliche Sensoren,
• - Digitale Übermittlung von Messwerten und
• - Übertragung von Geräteparametern und Diagnosedaten.

Industrial communication sensors master three types of communication:

• - Binary, like conventional sensors,
• - Digital transmission of measured values and
• - Transmission of device parameters and diagnostic data.

the DE 10 2016 221 662 B4 The applicant discloses an adapter for controlling a field device via an IO-Link system, the IO-Link system representing an embodiment of the considered industrial communication systems working according to IEC 61131-9.

the DE 10 2016 217 706 B4 the applicant describes an intermediate unit for the IO-Link system for bidirectional data transmission over long 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.

the EP 2 256 566 B1 describes a field device with a control device and a method for controlling it. The control unit is designed to selectively assume a working mode and a sleep mode, with the control unit sending a deactivation signal to the monitoring unit before entering the sleep mode, and the monitoring unit being designed to bring the control unit back into the working mode after receiving an activation signal.

the EP 3 598 078 A1 teaches how to operate a field device in an energy-saving manner, ie switch off consumers that are not required. A controlled power storage unit is available for this purpose.

the EP 3 598 079 A1 discloses a battery-operated field device with an energy store connected to a control unit. The field device has loads that are connected to the energy store via a controllable switch, so that they can all be switched off. In one embodiment, only certain components are powered and others are kept in a sleep mode. Furthermore, a console is proposed, which can be plugged into the field device for maintenance and used to update software. The console can also be set up for a connection to the energy store and contain a power supply that is suitable for charging a rechargeable energy store of the field device.

The disadvantage of the prior art is, on the one hand, that in the event of a fault in the power supply, the current process value cannot easily be read out. On the other hand, there is no efficient way to manually operate field devices in hard-to-reach positions in the event of a power failure. A tool that can be used flexibly in the event of a power failure is being sought to support service personnel.

The object of the invention is seen in further improving the state of the art. The service staff should be able to react more flexibly and efficiently to disruptions in the power supply. In particular, a possibility should be created to manually operate field devices in positions that are difficult to reach, for example to read out the current or last process value.

This object is solved according to claims 1 and 6. The dependent claims relate to advantageous configurations of the arrangements according to the invention.

The main idea of the invention is to create an operating unit to be arranged between a field device and its supply unit, hereinafter referred to as a power box, which is suitable for detecting undervoltage on the field device and, in the event of a power failure or even just undervoltage, switches the field device to a power-saving mode to move and wake up again, the field device being supplied with power from the power box in power-saving mode, and the current (last) process value being able to be displayed or read out.

As has been found, the above-mentioned industrial communication connection offers a hitherto unfeasible possibility of creating a power box with a battery pack and a simple, flexible communication interface to a field device (sensor).

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.

In a second advantageous embodiment, the power box can be designed to query a suitable control button of the field device and thus cause the field device to display a desired process value.

In a third advantageous embodiment, the power box has a display for showing the process value mentioned above.

It goes without saying that the use of the power box according to the invention just described requires a field device capable of industrial communication (industrial communication device), which is to be programmed in the desired manner. In particular, the field device must be designed to switch to an industrial communication command in a power-saving mode (sleep mode), the field device being put into a state in which only assemblies required to display the last process value are supplied with power. The power box can of course also wake up using a power down command from the field device/device. Then the sensor simply restarts.

The power box according to the invention consists essentially of a battery pack with an interface to the sensor that is capable of industrial communication. The power box supplies the connected sensor in the event of a power failure or undervoltage and commands it into a power-saving mode. The sensor wakes up from this power-saving mode when the supply voltage is available again. In this case, it returns to its normal state.

After the power supply returns from the higher-level (programmable logic controller) (PLC), a sub-assembly such as an industrial communication master gateway or a power supply unit, the time of the failure and the state of charge of the batteries are reported to the controller. This can either be used to initiate maintenance or to predict future availability.

In power saving mode, the display remains dark until a key is pressed. Then it only displays the process value for a few seconds. (Comparable to a display off function.)
This makes maintenance on the machine or industrial plant possible, since the process value can still be reliably displayed even in the event of a power failure.
It is also possible to wake up the sensor via a button or a communication command via the power box. This makes it possible to activate a sensor that is difficult or, in extreme cases, not accessible at all (e.g. on a tank).
This increases the operational readiness and reduces the necessary capacity of the batteries, which allows the use of maintenance-free ultra capacitors (Super Caps, Gold Caps, etc.).

• 1 zeigt die elektronische Schaltung der Power-Box in einer vereinfachten Darstellung,
• 2 zeigt die zwischen einem Feldgerät und der Stromversorgung angeordnete Power-Box.

The invention is explained in more detail with reference to the drawing.

• 1 shows the electronic circuit of the power box in a simplified representation,
• 2 shows the power box arranged between a field device and the power supply.

the 1 describes a simplified electronic circuit of the power box. It has an energy store 1, a first connection 2, a second connection 3 and a control unit 4, the first connection 2 for connection to a field device 5 and for its power supply, and the second connection 3 is used for connection to a supply unit 6 . Furthermore, an industrial communication interface 7 designated as communication module is present.

If the supply drops below a threshold value (e.g. to 18 V, see specification of industrial communication), a regulator (e.g. a step-up converter) from a connected energy store, battery or capacitor 1 provides electrical energy for the field device 5. In this case, the power supply of a field device 5 (not shown explicitly here) is ensured during the power failure.

A unit designated supply (circuit) ensures the power supply of the control unit 4 (control unit). This takes over the control of a controller labeled Charge control & converter and the communication interface 7 (communication module).
In addition, the input voltage is permanently monitored.
The state of charge of the energy store 1 (C1) is also recorded with the control unit and, if there is an available industrial communication master gateway, a PLC, or another higher-level control unit, it is transmitted to it. This means that maintenance can be carried out if necessary, or a possible bridging time can be calculated.
In order to charge the energy store 1, the charge control contains a suitable charging circuit, which fills up the energy store 1 when the power supply is available.

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. If the supply voltage is present, it is transparent and simply forwards the commands to and from the field device 5 . The AUX connection can be used to pass through analog signals from (and to) the connected field device (device) 5 .

In the event of undervoltage, the power box commands the field device 5 into a sleep mode, with the field device 5 reducing its power requirement to a minimum. Nevertheless, instead of the usual cycle time of 0.4 to 132 milliseconds for the IO-Link system considered here as an example, it should be at longer intervals, e.g. B. every 3...30s, switch on its specially equipped IO-Link receiver and determine the process value if necessary. This significantly increases the time during which a power failure can be bridged. However, this requires an IO-Link receiver that understands IO-Link communication but allows longer cycle times because a standard-compliant IO-Link master would report a communication error at more than 132 milliseconds.

This requires a software adaptation of the field device, because IO-Link devices are designed in such a way that if communication breaks down because the master does not keep to the cycle, it remains in communication mode, but error messages can occur. A special version is therefore required that does not follow the IO-Link standard and thus allows a longer cycle time. If none of this is desired, a standard field device can also be connected here. Then the power box only serves as a UPS (uninterruptible power supply).

the 2 shows the power box arranged between the field device 5 and the power supply 6 . An IO-Link connection is shown, which acts here as an industrial communication connection. A higher-level control unit (SPS), which is not absolutely necessary for the explanation, can be connected to the line marked SPS. It would function here as the master gateway for industrial communication, in this case as the IO-Link master.

As already shown in more detail above, the power box has a first connection 2 , a second connection 3 and a control unit 4 in addition to the energy store 1 . The first connection 2 is used for connection to a field device 5 and for its power supply. The second connection 3 is used to connect to a (current) supply unit 6, which as a rule belongs to a higher-level control unit (PLC). There is also an industrial communication interface 7 designed as an IO-Link for bidirectional communication.

In addition, a control button 8 for the manual input of control commands for the control unit and thus also for the field device 5 is shown. For example, the button 8 can be designed to trigger a measurement cycle on demand.

In a further embodiment, this can be automatically timed, e.g. B. every 2 minutes, whereby the process value (measured value) is always displayed for 30 s, whereby the times can of course be adapted to the application using parameters.

A display 9 can serve both to inform the service personnel and, according to the invention, to display at least one process value.

Reference List

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)

8th

control button

9

screen

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• DE 102016221662 B4 [0007]
• DE 102016217706 B4 [0008]
• EP 2256566 B1 [0009]
• EP 3598078 A1 [0010]
• EP 3598079 A1 [0011]

Claims (6)

Operating unit for a field device, with an energy store (1), a first connection (2), a second connection (3) and a control unit (4), the first connection (2) for connection to a field device (5) and to its power supply 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 connect a field device (5) capable of industrial communication in the event of a power failure or in the event of undervoltage, to put it into a power-saving mode and to wake it up again, the field device (5) being supplied in the power-saving mode from the energy store (1), and the field device (5) in the power-saving mode being able to be put into a state by a command in which a process value is displayed. Operating unit according to claim 1 , with an operating button (8) for triggering an industrial communication command for the field device (5). Operating unit according to claim 1 , characterized in that a process value is always displayed for a second time at first time intervals, it being possible for these times to be adjusted by parameters. Operating unit according to claim 1 , designed to interrogate an operating button of the field device (5), from which a trigger command for industrial communication is transmitted to the field device (5). Operating unit according to claim 1 or 2 , with a display (9) for displaying a process value of the field device (5). Field device (5) capable of industrial communication, designed to switch to an industrial communication command in a power-saving mode, the field device (5) being put into a state in which the assemblies required to display a process value are supplied with power.

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