WO2020025208A1

WO2020025208A1 - Method for determining calibration cycles for a field device in a process automation system

Info

Publication number: WO2020025208A1
Application number: PCT/EP2019/065456
Authority: WO
Inventors: Reinhard Buchner; Markus Kilian; Ralf Schmidt; Eric Birgel
Original assignee: Endress+Hauser Wetzer Gmbh+Co. Kg
Priority date: 2018-07-31
Filing date: 2019-06-13
Publication date: 2020-02-06
Also published as: DE102018118533A1

Abstract

The invention relates to a method for determining calibration cycles for a field device (FG1, FG2, FG3, FG4, FG5) in a process automation system (A), comprising: transferring the process values and the further data of the field devices (FG1, …, FG5) to a service platform (SP), in particular a cloud-based service platform, by means of the superordinate unit (GW, SPS); creating history data on the basis of the transferred process values and the further data for each of the field devices (FG1, …, FG5); establishing a comparison system (VS) on the basis of the history data, the service platform (SP) or an application running on the service platform (SP) determining, in the course of the establishing of the comparison system (VS), which first process variable (P1) of a first sensor unit (SE1, …, SE5') can act as a comparison variable for a second process variable (P2) of a second sensor unit (SE1, …, SE5'); capturing the first process variable (P1) and the second process variable (P2), continuously or at fixed time points; comparing the first process variable (P1) with the second process variable (P2) and determining a deviation of the second process variable (P2) from the first process variable (P1); and creating a maintenance notification (WN) if the second process variable (P2) deviates from the first process variable (P1) by a predefined maximum value (ΔT).

Description

Method for determining calibration cycles for a field device in a process automation system

The invention relates to a method for determining calibration cycles for a field device in a process automation system, a plurality of field devices being provided in the system, each of the field devices having at least one sensor unit which is designed to record at least one process variable, the Field devices are integrated in a first communication network and communicate with a higher-level unit, the field devices transmitting the collected process values and further data, in particular diagnostic data, parameter data and status information, to the higher-level unit via the communication network, the higher-level unit transmitting the collected process values and the further ones Data transmitted to a control center of the plant.

Field devices that are used in industrial plants have already become known from the prior art. Field devices are widely used in automation technology as well as in production automation. In principle, field devices are all devices that are used close to the process and that supply or process process-relevant information. Field devices are used to record and / or influence process variables. Sensor units are used to record process variables. These are used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, pFI measurement, level measurement, etc. and record the corresponding process variables pressure, temperature, conductivity, pFI value, level, flow etc. Actuator systems are used to influence process variables. These are, for example, pumps or valves that can influence the flow of a liquid in a pipe or the level in a container. In addition to the aforementioned

Measuring devices and actuators are understood as field devices also remote I / Os, radio adapters or generally devices that are arranged on the field level.

In modern industrial plants, field devices are usually over

Communication networks such as field buses (Profibus®, Foundation® Fieldbus, HART®, etc.) connected to higher-level units. The higher-level units are control units, such as a PLC (programmable logic controller) or a PLC (programmable logic controller). The higher-level units are used, among other things, for process control and for commissioning the field devices. The measured values recorded by the field devices, in particular by the sensor units, are transmitted via the respective bus system to one (or possibly several) higher-level unit (s), which process the measured values if necessary and forward them to the control center of the system. The control center is used for process visualization, process monitoring and process control via the higher-level units. Next to it is also one

Data transmission from the higher-level unit via the bus system to the

Field devices required, in particular for the configuration and parameterization of field devices and for controlling actuators.

To ensure that the measured values from the sensor units of the field devices correspond to the actual value, the field devices or their sensor units are calibrated during commissioning. The sensor unit is set in such a way that its measured values correspond to the measured values of a calibrated reference device.

During the operation of a field device, calibration cycles take place in a defined time sequence (so-called calibration cycles), regardless of the state of the sensor unit. On the one hand, this means that a calibration is carried out even if it is not necessary. The opposite can also be the case: a calibration is actually required but not yet planned / planned. On the other hand, the process may have to be stopped for calibration purposes, which can result in high costs.

On the basis of this problem, the object of the invention is to present a method which allows calibration cycles of a field device to be dynamically adapted. The task is accomplished through a method of determining calibration cycles for a

Field device in a process automation system, wherein a plurality of field devices are provided in the system, each of the field devices having at least one sensor unit that is designed to record at least one process variable, the field devices being integrated in a first communication network and with a higher-level unit communicate, the field devices, the collected process values and other data, in particular

Diagnostic data, parameter data and status information about the

Transmit communication network to the higher-level unit, the higher-level unit transmitting the collected process values and the further data to a control center of the system, comprising:

- Transmission of the process values and the further data of the field devices to a, in particular cloud-based, service platform by means of the higher-level unit;

- Creation of flistorien data on the basis of the transmitted process values and the further data for each of the field devices;

- Establish a comparison system based on the history data, the

Service platform, or an application running on the service platform, determines which first in the course of establishing the comparison system

Process variable of a first sensor unit for a second process variable of a second sensor unit can act as a comparison variable;

- Detection of the first process variable and the second process variable, continuously or at specified times;

- Compare the first process variable with the second process variable and

Determining a deviation of the second process variable from the first

Process variable; and

- Creation of a maintenance notification in the event that the second process variable deviates from the first process variable by a predetermined maximum value.

The advantage of the method according to the invention is that no rigid, predetermined calibration times have to be used for the calibration of a field device or a sensor unit of the field device. The field device, or its

The sensor unit is calibrated when calibration is actually necessary. To determine the necessity, the sensor unit becomes a further sensor unit assigned, which ideally collects the same process variable or a comparable process variable. In order to select the suitable comparison variable, the collected values of the process variables are compared with one another. If these agree with the predetermined process variable with a predetermined accuracy, then a process variable can potentially be used as a comparison variable. It is provided that the process variable that has the highest accuracy in relation to the first process variable is selected.

In the event that the values of the two sensor units differ from one another over time by a predetermined value, in particular a difference value, a calibration order or a maintenance notification is created.

In the event that the first and the second process variable soften a constant systematic offset, this can be corrected directly so that the

Maintenance notification is only detected due to a detected time-varying deviation of the two process variables.

Examples of field devices and their sensor units, which are mentioned in connection with the method according to the invention, have already been described as examples in the introductory part of the description.

According to an advantageous development of the method according to the invention, it is provided that more are established in the course of establishing the comparison system

Properties of a field device or a sensor system of the field device are transmitted to the higher-level unit and compared. The accuracy of the suitability of the comparison variable is increased because not only the pure process measurement values of the actual process variable are compared with potential comparison variables, but further metadata are also included. These additional data are included in the calculation of the accuracy of a potential comparison variable.

In a preferred embodiment of the method according to the invention

provided that the other properties provide information regarding the

include the geographic location of the field device. In an advantageous embodiment of the method according to the invention, it is provided that further properties contain information relating to the measuring point in which the field device is installed and / or the function of the field device in the measuring point.

In a preferred embodiment of the method according to the invention

provided that the further properties are transmitted from the field devices or from the service platform to the higher-level unit. For example, this information can be collected by the field devices themselves,

for example the information regarding the location of the field devices. An operator can enter the additional information on the service platform, for example, or have his own databases included on the service platform. To record their information regarding the location, field devices have, for example, GPS sensors or GSM modules, by means of which the information is collected.

In an advantageous embodiment of the method according to the invention it is provided that in the course of establishing the comparison system flistoria data,

Location information and / or information relating to a measuring point can be used by field devices which are located in other systems that are different from the system. In this way, the knowledge of other measuring points can be accessed and the quality of the comparison variable can be further increased. This additional information is also located on the service platform or on other platforms that have interfaces for data exchange with the service platform.

According to an advantageous development of the method according to the invention, it is provided that the service platform, or the application running on the service platform, checks the type of the first and the second physical measurement variable and the physical measurement principle of the first and the second sensor unit.

In an advantageous embodiment of the method according to the invention, it is provided that the first process variable is only used as a comparison variable for the second process variable if the first and the second physical measured variable are of the same Type and if the first and second sensor units have a different physical measurement principle.

In a preferred embodiment of the method according to the invention

provided that the service platform, or the application running on the service platform, uses a KI algorithm, in particular based on neural networks.

In an advantageous embodiment of the method according to the invention, it is provided that the service platform, or the application running on the service platform, determines the predetermined maximum value of the deviation of the second process variable from the first process variable in the course of establishing the comparison system on the basis of the history data. For example, short-term deviations of the two process variables from one another can be seen in the history data. The maximum value should therefore be chosen such that such short-term deviations do not lead to the creation of a maintenance notification.

In an advantageous embodiment of the method according to the invention, it is provided that a wire-based, in particular an Ethernet-based, communication network is used as the communication network. This can also be a fieldbus of automation technology, for example based on one of the protocols HART, Profibus PA / DP, Foundation Fieldbus, etc. It can also be provided that the first communication network consists of several

Sub-segments exist, which may be based on different protocols.

In a preferred embodiment of the method according to the invention it is provided that a wireless communication network is used as the communication network. In particular, this is based on the WLAN or WiFi standard. Alternatively, any other common wireless standard can be used.

The invention is explained in more detail with reference to the following figures. Show it 1: a schematic overview of a process automation system in which the method according to the invention can be carried out; and

2: an application example of the method according to the invention.

1 shows parts of a plant A of automation technology. Specifically, there are two measuring points MS1, MS2. These each consist of a tank and a pipe leading away from the tank. To measure the fill level of the tank as a process variable, a field device FG1, FG4, for example a fill level measuring device, is attached to the tank by means of a radar as sensor unit SE1, SE4. To measure the flow rate in the pipeline, a field device FG3, FG5 is attached, the sensor unit SE3, SE5 of which

Flow rate of a medium flowing through the pipeline is determined as the primary process variable according to the Coriolis principle. Each of the field devices F3, F5 also has a temperature sensor SE3 ', SE5' as further

Sensor unit that detects the temperature of the medium flowing through the pipeline as a secondary process variable. Furthermore, a further field device FG2 is installed in the measuring point MS1, which determines the temperature of the measuring medium flowing through the pipeline by means of a high-precision temperature sensor SE2 as a sensor unit.

The field devices FG1, ..., FG5 are interconnected by means of a first

Communication network KN1 connected and are in each other

Communication link. The first communication network KN1 is in particular an Ethernet network. Alternatively, the first communication network KN1 is a fieldbus according to one of the known

Fieldbus standards, e.g. Profibus, Foundation Fieldbus or FIART.

The first communication network KN1 contains a higher-level unit PLC, for example a programmable logic controller, which transmits commands to the field devices FG1, ..., FG5, whereupon the field devices FG1, ..., FG5

Process values, diagnostic data and status information to the higher-level unit Submit PLC. These process values, diagnostic data and status information are forwarded by the higher-level unit PLC to a workstation PC in the control center LS of system A. This serves, among other things, for process visualization,

Process monitoring and for engineering such as for operating and monitoring the field devices FG1, ..., FG5.

Furthermore, the first communication network KN1 contains a gateway GW, which overhears the process values, diagnostic data and status information transmitted from the field devices FG1, ..., FG5 to the higher-level unit PLC and makes it available via the Internet to a service platform SP stored on a cloud. The service platform SP is designed to run applications.

For example, such an application is a plant asset management system which is used to manage the assets, that is to say the inventory, of system A.

An application of the method according to the invention is described below:

In order to detect the need for recalibration of one of the field devices FG1,..., FG5 as quickly as possible, a so-called comparison system VS is established. The comparison system VS serves the purpose of defining which

Process variable of a field device FG1, ..., FG5, or a sensor unit SE1, ..., SE5 ', similar to a process variable of a further field device FG1, ..., FG5, or a further sensor unit SE1, ... , SE5 ', behaves and thus as a comparison or

Reference size can act.

For this purpose, the information of the field devices FG1, ..., FG5 transmitted to the service platform SP is analyzed. Based on the process values of the individual field devices FG1, ..., FG5, or their sensor units SE1, ..., SE5 '

Flistoriendaten for each of the field devices FG1, ..., FG5, or each of the sensor units SE1, ..., SE5 'created. The history data depict the time course of the process values.

Then the history data of the individual field devices FG1, ..., FG5, or their sensor units SE1, ..., SE5 'are compared with one another and matches searched. If history data match the first process variable with a predetermined accuracy, then a process variable is potentially a possible comparison variable. In addition, it can be checked and taken into account for the evaluation whether the field devices FG1, ..., FG5 which provide the comparative process variables are geographically close to one another, whether the application of the

Process variables are similar, as well as whether the physical measuring principles differ from each other. For the creation of the comparison system VS, an application application that uses Kl algorithms runs on the service platform SP.

2 shows an application example of the method according to the invention. in the

Comparison system VS defines that the process variable P2 of the temperature sensor SE3 'of the field device FG3 is used as a comparison variable of the process variable P1 of the

Temperature sensor SE2 of the field device FG2 can function. When analyzing the history values of both process variables P1, P2, it emerged that the historical course of both process variables is largely the same. In addition, both sensor units SE2, SE3 'are arranged close to one another and both measure the temperature of the measuring medium flowing through the pipeline. It is also advantageous that the two sensor units SE2, SE3 'use a different physical measuring principle. Sensor unit SE2 uses a PTC thermistor (PTC resistor), while sensor unit SE3 uses a thermistor (NTC resistor). A slow drift over time, which could be caused by the measuring principle, could be detected, which would not be possible if both sensor units SE2, SE3 'would use the same physical measuring principle.

2 shows the time course of the process variables P1 and P2 from the establishment of the comparison system VS. The abscissa shows the elapsed time t; the ordinate shows the value of process variables P1 and P1 as temperature T,

for example in Kelvin. Up to the point in time ti, both process variables P1 and P2 behave very similarly and only have a small systematic offset. From the time ti, the distance between the two process variables P1, P2 increases continuously, for example due to a long-term drift of the sensor unit SE3 '. As soon as the distance between the process variables P1, P2 reaches or exceeds a predetermined distance DT, a maintenance notification WN is created and on the control center LS of plant A transmitted. In this way, a check of both sensor units SE2, SE3 'and a possible recalibration of at least one of the two sensor units SE2, SE3' is initiated. The comparison of process variables P1, P2 can be carried out by different components of system A. For example, this function can be performed by the

higher-level unit PLC, from the gateway GW, from the service platform SP or directly in the control center LS. The corresponding components require knowledge of the comparison system VS, which the service platform SP can provide.

It can also be provided that the comparison system VS is created by the gateway GW. In this case, the gateway GW needs the corresponding one

Functionalities that enable the comparison system VS to be created.

In addition, the gateway GW must be able to access the flistory data of all field devices FG1, ..., FG5 on the service platform SP.

LIST OF REFERENCE NUMBERS

A plant of automation technology

FG1, FG2, FG3, FG4, FG5 field device

GW parent unit, gateway

KN communication network

LS control center of the plant

MS1, MS2 measuring point

P1 first process variable

P2 second process variable

SE1, SE2, SE3, SE3 ', SE4, SE5, SE5' sensor unit

SP service platform

PLC higher-level unit, control

DT predetermined maximum value of

deviation

VS comparison system

WN maintenance notification

Claims

claims

1. A method for determining calibration cycles for a field device (FG1, FG2, FG3, FG4, FG5) in a plant (A) of process automation, with a plurality of field devices (FG1, FG5) being provided in the plant (A), wherein each of the field devices (FG1, ..., FG5) has at least one sensor unit (SE1, SE2, SE3, SE3 ', SE4, SE5, SE5'), which is designed to collect at least one process variable (P1), the field devices (FG1, ..., FG5) in one

Communication network (KN) are integrated and communicate with a higher-level unit (GW, PLC), the field devices (FG1, ..., FG5) the collected process values and other data, in particular diagnostic data,

Transmit parameter data and status information via the communication network (KN) to the higher-level unit (GW, PLC), whereby the higher-level unit (GW, PLC) or a further higher-level unit (GW, PLC) transmit the collected process values and the further data to a control center ( LS) of the system (A), comprising:

- Transmission of process values and other data from the field devices

(FG1, ..., FG5) to a, in particular cloud-based, service platform (SP) by means of the higher-level unit (GW, SPS);

- Creation of flistorien data on the basis of the transmitted process values and the further data for each of the field devices (FG1, ..., FG5);

- Establishing a comparison system (VS) on the basis of the historical data, the service platform (SP) or an application running on the service platform (SP) determining which first process variable (P1) of a first one in the course of establishing the comparison system (VS) Sensor unit (SE1, ..., SE5 ') for a second process variable (P2) of a second sensor unit (SE1, ...,

SE5 ') can act as a comparative variable;

- Detecting the first process variable (P1) and the second process variable (P2), continuously or at fixed times;

- Comparing the first process variable (P1) with the second process variable (P2) and determining a deviation of the second process variable (P2) from the first process variable (P1); and - Create a maintenance notification (WN) in the event that the second

Process variable (P2) deviates from the first process variable (P1) by a predetermined maximum value (DT).

2. The method according to claim 1, wherein in the course of establishing the comparison system

(VS) further properties of a field device (FG1, FG5), or one

Sensor unit (SE1, SE5 ') of the field device (FG1, FG5) to which

Service platform (SP) are transmitted and compared.

3. The method of claim 2, wherein the further properties information

regarding the geographic location of the field device (FG1, ..., FG5).

4. The method according to claim 2 or 3, wherein the further properties information relating to the measuring point in which the field device (FG1, ..., FG5) is installed, and / or the function of the field device (FG1, ..., FG5) included in the measuring point.

5. The method according to at least one of claims 2 to 4, wherein the further

Properties of the field devices (FG1, ..., FG5) are transmitted to the service platform (SP) by means of the higher-level unit and / or the further properties are transmitted from a database to the service platform (SP).

6. The method according to at least one of claims 2 to 5, wherein in the course of

Establishment of the comparison system (VS), flistory data, position information and / or information relating to a measuring point of field devices (FG1, ..., FG5), which are located in other plants (A) that are different from plant (A).

7. The method according to at least one of claims 2 to 6, wherein the service platform (SP), or the application running on the service platform (SP), the type of the first and the second physical measurement variable (P1, P2) and the physical measurement principle of the first and the second sensor unit (SE1, ..., SE5 ') checked.

8. The method according to claim 7, wherein the first process variable (P1) only as

Comparison variable for the second process variable (P2) is used when the first and the second physical measured variable are of the same type and if the first and second sensor units (SE1, SE5 ') are different physical ones

Show measurement principle.

9. The method according to at least one of the preceding claims, wherein the

Service platform (SP), or the one running on the service platform (SP)

Application, a Kl algorithm, in particular based on neural

Networks.

10. The method according to at least one of the preceding claims, wherein the

Service platform (SP), or the one running on the service platform (SP)

Application, in the course of establishing the comparison system (VS) based on the history data, the predetermined maximum value (DT) of the deviation of the second process variable (P2) from the first process variable (P1).

1 1 .Method according to at least one of the preceding claims, wherein as

Communication network (KN) a wired, in particular an Ethernet-based, communication network is used.

12. The method according to at least one of claims 1 to 10, wherein as

Communication network (KN) a wireless communication network is used.