DE102020134409B3 - Intermediate unit for a field device with an energy store and method - Google Patents

Abstract

Intermediate unit for a field device with a first connection 2, a second connection 3 and a control unit 4, wherein the first connection 2 is designed for connection to a field device 5 and for its power supply, and the second connection 3 is designed for connection to a master unit 6, as well as has an industrial communication interface 7, characterized in that the intermediate unit has an energy store 1 and is designed in such a way that a field device 5 with industrial communication capability can be switched to a power-saving mode in the event of a power failure or low voltage and be woken up again, with the field device 5 is supplied from the energy store 1, and the field device 5 in the power-saving mode can be put into a state by a command in which a process value is displayed. Furthermore, a method for operating an industrial communication interface 7 is claimed.

Description

The invention relates to an intermediate unit, also referred to below as a repeater, for a field device from process automation or process measurement technology with an energy store according to claim 1 and a method according to claim 5.

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 fieldbuses, 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 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. In addition, an expansion module is proposed, which can be designed for storing and displaying data, but also as a configuration tool.

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.

As a further state of the art DE 102007045884 A1 as well as the DE 102013114195 A1 to call.

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 is not can be read out easily. On the other hand, there is no efficient way of reading field devices in hard-to-reach positions, even 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 read field devices at positions that are difficult to reach with a display that is not visible or only difficult to see, in order to obtain the current or last process value even if the higher-level controller fails.

This object is achieved according to claim 1. Claim 5 relates to the use of the arrangements according to the invention.

The essential idea of the invention is to specify an intermediate unit (repeater) to be arranged between the field device and its supply unit, which is suitable for detecting undervoltage on the field device and, in the event of a power failure or even just undervoltage, to put the field device into a power-saving mode and wake it up again , wherein the field device is supplied with power from the intermediate unit in power-saving mode, and wherein the current (last) process value can be displayed or read out.

As has been found, the above-mentioned industrial communication connection offers a previously unfeasible possibility of creating such an intermediate unit with its own power supply and a simple yet flexible communication interface to the field device (sensor) and specifying a method for its operation.

The communication interface according to the invention of the intermediate unit always behaves like a “normal” interface with respect to the higher-level (memory-programmable) controller (PLC). In the event of undervoltage, and only then, is the cycle time extended to the field device by no longer forwarding every master telegram to the field device.

In the simplest case, this can be done by temporarily switching off a "normal" field device or by using a special field device with a longer cycle time.

In an advantageous embodiment, a process value is shown permanently on a display. In the event of a power failure, the field device is first switched off and only switched on again when a control command is given by pressing a button or after a time regime to be defined, and then a (last or current) process value is displayed. As an alternative to this, it is also conceivable for the process value to be displayed on the display of the field device 5 if this has its own display.

In a further advantageous refinement, there are a number of ports for a number of field devices (devices), the field devices being supplied with power and their process values being displayed via a power management system. In this case, the field devices (devices) can be supplied with power periodically all at the same time or sequentially individually.

In addition to the display, the intermediate unit can be designed for the acoustic output of the process value to be displayed.

It goes without saying that the use of the intermediate unit according to the invention 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 intermediate unit can of course also force the wake-up via a power-down command for the field device/device. Then the sensor simply restarts.

The intermediate unit according to the invention consists essentially of a power storage device, an interface capable of industrial communication to the field device (sensor), a display, and at least one control element, preferably a button.

According to a method also belonging to the invention, the intermediate unit supplies the connected field device (sensor) with power in the event of undervoltage, but commands it into a power-saving mode with a cycle time that is at least one power of ten higher, from which it is woken up when the supply voltage is available again. The field device is then returned to its normal state.

After power returns from the higher-level (programmable logic) controller (PLC) or a sub-assembly such as An industrial communication master gateway or a power supply unit can report the time and duration of the failure as well as the status of the power storage to the controller. In this way, maintenance can be initiated and/or future availability can be predicted.

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 a machine or production system possible even in the event of a power failure, because the process value can also be reliably displayed in such a case.

It is thus possible to wake up the sensor via a button or a communication command via the intermediate unit. In this way, a field device (sensor) that is difficult to reach or, in extreme cases, cannot be reached at all, for example that is arranged on a tank, can be activated. On the one hand, this increases operational readiness and, on the other hand, reduces the necessary capacity of the power storage in the intermediate unit, which allows the use of maintenance-free ultra capacitors (Super Caps, Gold Caps, etc.).

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

1 shows the intermediate unit arranged between the field device and the master unit.

the 1 shows an intermediate unit according to the invention in a greatly simplified representation. It has an energy store 1, a first connection 2, a second connection 3 and a control unit 4, with the first connection 2 for connecting to a field device 5 and for its power supply and the second connection 3 for connecting to a master and supply unit 6 serves. Furthermore, there is an industrial communication interface 7, here a (special) IO-Link interface, which according to the invention can have different cycle times to the field device 5 and to the master and supply unit 6.

If the supply drops below a threshold value (e.g. to 18 V, see specification of industrial communication), the field device 5 is fed from the energy store 1, a battery or capacitor, so that the (emergency) power supply of the field device 5 during the power failure is ensured.

In the event of undervoltage, the intermediate unit commands the field device 5 according to the above-mentioned The sleep mode specified in the method belonging to the invention, 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. switch on its specially equipped IO-Link receiver every 3...30s and determine the process value if necessary. This significantly increases the time during which a power failure can be bridged. This requires a generic 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.

In addition, a software adaptation of the field device 5 is required, because IO-Link devices are designed in such a way that if the 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.

The IO-Link connection shown here acts as an industrial communication connection. The master and supply unit 6, shown extremely schematically, is part of a higher-level controller SPS. It acts as the master gateway for industrial communication, in this case as the IO-Link master.

The industrial communication interface designed as IO-Link is used for bidirectional communication. The display 8 shown by way of example as part of the control unit 4 can advantageously not only display at least one process value, but can also display the duration of the downtime or the remaining operating time to the service personnel. However, the intermediate unit does not necessarily have to have a display 8 itself. Likewise, it is also conceivable that the display of the process value is shown on the display of the field device 5 if this has its own display.

In addition, a control button 9 for manually entering control commands is shown. The button can, for example, trigger a measurement cycle on demand and thus also represents a control element for the field device 5.

In an advantageous 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.

The intermediate unit equipped with a preferably chargeable energy store 1 can also be designed to permanently display the process value and first switch off the field device only in the event of a power failure and then supply the field device 5 either automatically in a specifiable time regime or on demand (via button 9) and display a new process value. The intermediate unit according to the invention can optionally serve as an autonomous display for a field device with industrial communication.

In addition, an industrial communication connection can be provided for feeding in or reading out data. It can also be connected to an additional external display unit. As a monitoring tool (sniffer), this picks up the data of the communication from and to the field device 5 and displays it on a display 8 .

The intermediate unit according to the invention can also have an (IO-Link) master display in order to display the process values of field devices connected to a number of ports. In the event of a power failure, they are supplied with electricity in a manner according to the invention. Only one end device is switched on at a time via power management and its process value is displayed, for example, as with a multiport manometer. The intermediate unit switches its ports or the connected field devices on and off again and again in order to query their process values in a power-saving manner. The ports can be switched on and off simultaneously or sequentially.

Reference List

1

energy storage

2

First connection

3

Second connection

4

control unit

5

field device

6

master and supply unit

7

Industrial communication interface (e.g. IO-Link interface)

8th

screen

9

control button

Claims (6)

Intermediate unit for a field device, with 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 designed for connection to a master unit (6) and has an industrial communication interface (7), characterized in that the intermediate unit has an energy store (1) and is designed in such a way that a field device (5) capable of industrial communication is used with a To put power failure or undervoltage into a power-saving mode and to wake it up again, wherein in power-saving mode the field device (5) is supplied from the energy store (1) and the field device (5) in power-saving mode can be put into a state by a command in which a process value is displayed. Intermediate entity according to claim 1 , characterized in that a process value is shown permanently on a display (8) and in the event of a power failure the field device (5) is switched off and is temporarily supplied with power either in a specific time regime or by control command via a button (9), wherein a process value is displayed. Intermediate entity according to claim 2 , characterized in that there are several ports for field devices (5), the field devices (5) being supplied with power via a power management system and their process values being displayed. Intermediate entity according to claim 3 , characterized in that the field devices (5) are periodically all simultaneously or sequentially individually supplied with power. Method for operating an industrial communication interface (7), wherein - the power supply of a field device (5) is monitored for undervoltage, - the field device (5) is put into a power-saving mode in the event of undervoltage, the field device (5) consisting of an intermediate unit according to claim 1 until 4 is supplied, - the power-saving mode is a sleep mode in which the cycle time of the industrial communication system under consideration is increased by at least one power of ten, - with process values being determined and displayed with the increased cycle time. procedure according to claim 5 , with a cycle time of 3...30 seconds.

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