Method for compensating a malfunction of a field device in an automation system

Abstract

Method for compensating a malfunction of a field device (FG1, FG2, FG3, FG4, FG5) in an automation system (A), where the system (A) contains a large number of field devices (FG1, ..., FG5), 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 measure at least one process variable, wherein the field devices (FG1, ..., FG5) are integrated in a first communication network (KN1) and communicate with a higher-level unit (PLC), wherein the field devices (FG1, ..., FG5) each transmit the at least one collected process variable to the higher-level unit (PLC) via the first communication network (KN1), and whereby the higher-level unit (PLC) transmits the measured process variables to a control center (LS) of the plant (A), comprehensive: - Transmission of the process variables of the field devices (FG1, ..., FG5) to a service platform (SP) via a gateway (GW); - Creation of historical data based on the transmitted process variables for each of the field devices (FG1, ..., FG5); - Establishing a replacement system (ES) based on the historical data, wherein the service platform (SP) or an application running on the service platform (SP) or the gateway (GW) determines, in the course of establishing the replacement system (ES), which process variable of a sensor unit (SE1, ..., SE5') can replace a process variable of another sensor unit (SE1, ..., SE5') with a predetermined accuracy as a replacement variable; - Transmitting the device status of the field devices (FG1, ..., FG5) and / or the sensor units (SE1, ..., SE5') to the gateway (GW); and - Transmission of the substitute value to the control center (LS) by means of the higher-level unit (PLC) in the event of the occurrence of at least one predetermined device status of a field device (FG1, ..., FG5) or a sensor unit (SE1, ..., SE5'), wherein, in the course of establishing the replacement system (ES), further properties of a field device (FG1, ..., FG5) or a sensor unit (SE1, ..., SE5') of the field device (FG1, ..., FG5) are compared, characterized by that in the course of establishing the replacement system (ES), historical data, location information and / or information regarding a measuring point (MS1, MS2) of field devices (FG1, ..., FG5) are used, which are located in other systems (A) different from the system (A).

Description

The invention relates to a method for compensating a malfunction of a field device in an automation technology installation. A method of the generic type can be found in DE 101 35 586 A1.Field devices have already become known from the prior art, which are used in industrial installations of automation technology. In process automation and in manufacturing automation, field devices are frequently used. Field devices are in principle all devices that are used close to the process and supply or process process relevant information. Field devices are thus used for detecting and / or influencing process variables. Sensor units are used to record process variables. These are used, for example, for pressure and temperature measurement, conductivity measurement, flow measurement, pH measurement, fill level measurement, etc., and record the corresponding process variables pressure, temperature, conductivity, pH value, fill level, flow rate, etc. Actuator systems are used to influence process variables. These are, for example, pumps or valves which can influence the flow of a liquid in a pipe or the fill level in a container. In addition to the aforementioned measuring devices and actuators, field devices are also understood to mean remote I / Os, radio adapters or generally devices which are arranged at the field level.In modern industrial plants, field devices are generally connected to superordinate units via communication networks such as fieldbuses (Profibus® Foundation® fieldbus, HART® etc.). The superordinate units are control units, such as an PLC (programmable logic controller). The superordinate units serve, inter alia, for process control and for starting up 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 a (or optionally a plurality of) superordinate unit(s), which optionally process the measured values further and forward them to the control station of the installation. The control station is used for process visualization, process monitoring and process control via the superordinate units. In addition, data transmission from the superordinate unit via the bus system to the field devices is also required, in particular for the configuration and parameterization of field devices and for the actuation of actuators. DE 10 2016 124 350 A1 discloses a system for monitoring an automation system in which a plurality of communication networks are present. GB 2 470 995 A discloses a method for monitoring a process on the basis of different measured process variables.The failure of a field device sometimes requires a great amount of cost and time. In particular in critical processes, the relevant installation part must be shut down until the field device has been repaired or exchanged. As an alternative to this, redundancies are often installed in the relevant plant part in advance. These are generally field devices identical to the field devices used, which replace a relevant field device in the event of a fault.DE 101 35 586 A1 discloses a reconfiguration method for compensating failures in a sensor system. Failure states are determined for the sensor system from deviations which result from a comparison of a number of states measured by at least one sensor of the system with a state estimated by a system model.Proceeding from this problem, the object of the invention is to provide a method which makes it possible to facilitate the maintenance of a plant of automation technology.According to a first teaching, the object is achieved by a method having the features of the first claim.The great advantage of the method according to the invention is that failures of a field device or its sensor units can be easily compensated. Instead of providing a redundant spare device, a spare variable is automatically determined by a gateway connected to the first communication network or by an application on a cloud, or also combined by both entities. The substitute variable is transmitted to the superordinate unit until a user ends the transmission. The failed field device can be repaired or replaced in the meantime without the affected plant part having to be shut down and the process having to be interrupted, whereby the availability of the process is increased.The substitute variable can also be formed from a combination of a plurality of process variables of one or more sensor units. For example, instead of a failed radar-based fill level measurement device, the process variables of a plurality of limit switches or pressure measurement devices can be combined in order to obtain a substitute variable for the fill level in a tank.The desired accuracy of the replacement size compared to the failed process size may be pre-determined by the user. As a result, field devices or sensor systems whose detected process variables deviate too much from the failed field device are not taken into account.In this way, for example, a temperature sensor can replace a failed temperature sensor. The field devices have knowledge of the type of the captured process variables of all field devices or their sensor units, and their typical variables.Examples of device states which trigger the transmission of the replacement variable are, for example, "maintenance required" and / or "device offline".Examples of field devices and their sensor units, which are mentioned in connection with the method according to the invention, have already been described by way of example in the introductory part of the description.According to the first teaching, it is provided according to the invention that, during the establishing of the replacement system, further properties of a field device or of a sensor unit of the field device are compared. The accuracy of the replacement variable is increased because not only are the pure process variables compared with potential process variables, but further metadata are included. This further data is included in the calculation of the accuracy of a potential replacement variable.In an advantageous embodiment of the method according to the invention, it is provided that the further properties contain information regarding the geographical position of the field device.In a preferred embodiment of the method according to the invention, it is provided that the further properties contain information regarding the measuring point, in which the field device is installed, and / or the function of the field device in the measuring point.In an advantageous embodiment of the method according to the invention, it is provided that the further properties are transmitted from the field devices to the service platform or to the gateway, wherein the further properties are stored on the service platform. For example, this information can be collected by the field devices themselves, for example the information regarding the position of the field devices. An operator can, for example, input the further information on the service platform or have his own databases read in on the service platform.Within the scope of the first teaching, it is provided according to the invention that, during the establishing of the replacement system, history data, position information and / or information relating to a measurement point of field devices are used, which are located in further installations different from the installation. This allows access to the knowledge of further measurement points and allows the quality of the replacement variable to be further increased. This further information is likewise located on the service platform or on further platforms which have interfaces for data exchange with the service platform.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 or the gateway uses an AI algorithm, in particular based on neural networks.According to a second teaching, the invention achieves the object by a method having the features of the fourth claim. A deviation of the replacement variable from the history data results, for example, from the fact that the sensor unit which detects the potential replacement variable has a different measurement principle than the sensor unit which detects the process variable to be replaced. Another installation location or another calibration of the sensor unit, which detects the potential substitute variable, can also lead to a deviation. The deviation may be constant, but a non-constant deviation, which is increased or decreased over time, for example, may also be detected.In an advantageous embodiment of the aforementioned method according to the second teaching, it is provided that the superordinate unit corrects the replacement variable in real time by the determined deviation. In the case of a constant deviation, the substitute variable is increased or decreased by this constant deviation as required. In the event that a non-constant deviation is present, the deviation to be corrected is calculated beforehand and continuously adjusted.In a third teaching, the invention achieves the object by a method having the features of the sixth claim. The evaluation of the substitute size is calculated from the accuracy of the substitute size and the deviation of the substitute size. The less constant the deviation of the replacement size is, and accordingly a reliable prediction of the replacement size is difficult, the more negative the evaluation of the replacement size fails.In a preferred embodiment of the aforementioned method according to the third teaching, it is provided that the set of the history data of the field device or of the sensor unit, which has the predetermined device status, is included in the calculation of the evaluation. The more history data of a field device or of a sensor unit are present, the more information about the behavior of this field device or of this sensor unit is present in the measuring point during operation, which increases the significance of the calculation.In an advantageous embodiment of the method according to the invention, it is provided that a wired, in particular an Ethernet-based, communication network is used as the first communication network. This may also be a field bus in automation technology, for example based on one of the protocols HART, Profibus PA / DP, Foundation Fieldbus, etc. It may also be provided that the first communication network consists of a plurality of subsegments 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 first communication network. In particular, this is based on the WLAN or WiFi standard. Alternatively, any other common wireless standard may be used.The invention is explained in more detail with reference to the following figure. It shows FIG. 1 : a first exemplary embodiment of the method according to the invention;FIG. 1 shows parts of a plant A of automation technology. Specifically, these are two measurement points MS 1, MS 2. These consist in each case of a tank and a pipeline leading from the tank. To measure the fill level of the tank as a process variable, a field device FG 1, FG 4, for example a fill level measuring device, is attached to the tank by means of a radar as a sensor unit SE 1, SE 4. For measuring the flow rate in the pipeline, a field device FG3, FG5 is attached in each case, the sensor unit SE3, SE5 of which determines the flow rate of a medium flowing through the pipeline as a primary process variable according to the Coriolis principle. Each of the field devices FG 3, FG 5 furthermore has a temperature sensor SE 3', SE 5' as a further sensor unit, which detects the temperature of the medium flowing through the pipeline as a secondary process variable. Furthermore, a further field device FG 2 is mounted in the measuring point MS 1, which field device determines the temperature of the measurement medium flowing through the pipeline by means of a high-precision temperature sensor SE 2 as sensor unit.The field devices FG 1,..., FG 5 are connected to one another by means of a first communication network KN 1 and are in communication connection with one another. The first communication network KN 1 is in particular an Ethernet network. Alternatively, the first communication network KN1 is a field bus according to one of the known field bus standards, for example Profibus, Foundation Field bus or HART.The first communication network KN 1 contains a superordinate unit SPS, for example a programmable logic controller, which transmits commands to the field devices FG 1,..., FG 5, whereupon the field devices FG 1,..., FG 5 transmit process variables to the superordinate unit SPS. These process variables are forwarded from the superordinate unit SPS to a workstation PC in the control center LS of the installation A. This serves, among other things, for process visualization, process monitoring and for engineering, such as for serving and monitoring the field devices FG 1,..., FG 5.Furthermore, the first communication network KN 1 contains a gateway GW, which listens to the process variables transmitted from the field devices FG 1,..., FG 5 to the superordinate unit SPS and makes them available via the Internet to a service platform SP stored on a cloud. The service platform is configured to run applications. For example, such an application is a plant asset management system, which is used for managing the assets, i.e. the inventory, of the installation A.The following describes an application of the method according to the invention:In order to be able to react to a failure of a field device FG 1,..., FG 5, or of a sensor unit SE 1,..., SE 5', of one of the field devices FG 1,..., FG 5, without the process of the installation A, or of the measurement points MS 1, MS 2, having to be interrupted, an application running on the service platform SP creates a replacement system ES. This includes all sensor units SE 1,..., SE 5' of the field devices FG 1,..., FG 5, their elevated process variables and, for each of the sensor units SE 1,..., SE 5', in each case a list of those sensor units SE 1,..., SE 5' which can replace one of the sensor units SE,..., SE 5' in the event of a failure as a replacement variable. Furthermore, for each of the replacement variables, an accuracy is calculated with which a replacement variable corresponds to the process variable to be replaced.To create the replacement system ES, the gateway acquires information of the field devices FG 1,..., FG 5 by monitoring the data traffic transmitted via the first communication network KN 1 or by directly querying the field devices FG 1,..., FG 5. The information recorded by the field devices FG 1,..., FG 5 is information regarding the type of process variables which can be detected by their sensor units SE 1,..., SE 5', information regarding the geographical position of the field devices FG 1,..., FG 5, information regarding the measurement points MS 1, MS 2 into which the field devices FG 1,..., FG 5 are installed, information regarding the function of the field devices FG 1,..., FG 5 in the measurement points MS 1, MS 2, information regarding process variables recorded by the sensor units SE 1,..., SE 5', and information regarding the history data of the process variables recorded by the sensor units SE 1,..., SE 5'. Furthermore, the device status of the field devices FG 1,..., FG 5, or the device status of their sensor units SE 1,..., SE 5', is elevated. The information collected by the gateway GW is then transmitted to the service platform. It can also be provided that at least a portion of this information and / or further information is already stored on the service platform SP, or that this information is read in, for example, from databases of the plant operator.By means of the large number of items of information about the field devices FG 1,..., FG 5, or their sensor units SE 1,..., SE 5', the application is taught onto the installation A using AI algorithms and the replacement system is created. In this case, recourse can be had to the experience of already existing replacement systems which were created for further installations, and this experience can be incorporated into the creation of the replacement system.In the example shown in FIG. 1, the temperature sensor SE 2 of the field device FG 2 fails some time after the replacement system ES has been created. The field device changes to the device status "maintenance required" and no longer detects new temperature values. The new device status is registered by the gateway and a replacement size is requested by the service platform. The service platform then applies the replacement system ES, determines replacement sizes for the failed process size, and compares the accuracy of each of the potential replacement sizes with one another.In the present example, two potential spare variables are determined: the elevated temperature value of the temperature sensor SE3' of the field device FG3, and the elevated temperature value of the temperature sensor SE5' of the field device FG5. The accuracy of the two potential spare variables are then compared with one another. The potential replacement size of the field device FG 5 provides a low, inadequate accuracy here. The field device FG 5 is located in a measurement point MS 2 different from the measurement point MS 1, so that the history data of the field devices FG 2 and FG 5 also deviate very greatly from one another.The potential replacement size of the field device FG 3 shows a high accuracy. The field device FG 3 is located in the same measurement site MS 1 in which the field device FG 2 is located. Except for a slight offset, the history data of the field devices FG 2 and FG 3 resemble one another, so that the replacement variable specifies the temperature of the measurement medium in the pipeline sufficiently well.The amount of offset is determined on the basis of the comparison of the history data of the process variable to be replaced with the history data of the replacement variable and is stored as a deviation.Subsequently, an evaluation of the replacement size can be calculated. This is calculated from the determined quality of the replacement size and the history data of the replacement size. In this case, a high evaluation is achieved because, besides the high quality of the replacement size, the history data shows little variation.The substitute variable is subsequently communicated together with the value of the deviation of the superordinate unit SPS. This continuously corrects the values of the replacement variable and continuously forwards the current values of the replacement variable to the control center LS of the installation under the entry "replacement variable SE2", where these can be used and evaluated until the field device FG2 is serviced. Alternatively, the superordinate unit SPS forwards the value of the deviation to the control center LS and does not correct the current values of the replacement variable.The great advantage of the method according to the invention is that the process does not have to be shut down and can be continued without problems. Depending on the criticality of the process, however, the required accuracy of the replacement variable must be set correspondingly high in order to be able to ensure safe further operation of the process.Alternatively, it can be provided that the gateway GW itself carries out the creation of the replacement system ES, the determination of the replacement variable, the calculation of the evaluation and / or the forwarding of the replacement variable and / or the value of the deviation to the superordinate unit SPS. It is likewise possible for these tasks to be divided between the application of the service platform and the gateway GW.The substitute variable can also be formed from a combination of a plurality of process variables of one or more of the sensor units SE 1,..., SE 5'. For example, instead of a failed radar-based fill level measurement device FG 1, FG 4, the process variables of a plurality of limit switches or pressure measurement devices (not shown in FIG. 1 ) can be combined in order to obtain a substitute variable for the fill level in a tank from one of the measurement points MS 1, MS 2.List of reference charactersA plant of automation technology ES replacement system FG1, FG2, FG3, FG4, FG5 field device GW superordinate unit, gateway KN1 first communication network LS control station of the plant MS1, MS2 measuring station SE1, SE2, SE3, SE3', SE4, SE5, SE5' sensor unit SP service platform SPS superordinate unit, controller

Claims

Method for compensating a malfunction of a field device (FG1, FG2, FG3, FG4, FG5) in a plant (A) in automation technology, wherein a multiplicity of field devices (FG1,..., FG5) are present 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 gather at least one process variable, wherein the field devices (FG1,..., FG5) are incorporated in a first communication network (KN1) and communicate with a superordinate unit (SPS), wherein the field devices (FG1,..., fg5) each transmit the at least one elevated process variable to the superordinate unit (SPS) via the first communication network (KN1), and wherein the superordinate unit (SPS) transmits the elevated process variables to a control center (LS) of the installation (A), comprising: - transmitting the process variables of the field devices (FG1,..., FG5) to a service platform (SP) by means of a gateway (GW); - generating history data on the basis of the transmitted process variables for each of the field devices (FG1,..., FG5); establishing a replacement system (ES) on the basis of the history data, wherein the service platform (SP) or an application running on the service platform (SP) or the gateway (GW) determines, during the establishing of the replacement system (ES), which process variable of a sensor unit (SE 1,..., SE 5') can replace a process variable of a further sensor unit (SE 1,..., SE 5') with a predetermined accuracy as a replacement variable; transmitting the device status of the field devices (FG 1,..., FG 5) and / or of the sensor units (SE 1,..., SE 5') to the gateway (GW); and - transmitting the replacement variable to the control center (LS) by means of the superordinate unit (SPS) in the event of at least one predetermined device status of a field device (FG1,..., FG5) or of a sensor unit (SE1,..., SE5'), wherein, during the establishing of the replacement system (ES), further properties of a field device (FG1,..., FG5) or of a sensor unit (SE1,..., SE5') of the field device (FG1,..., FG5) are compared, characterized in that, during the establishing of the replacement system (ES), history data, position information and / or information relating to a measurement center (MS1, ms2) of field devices (FG1,..., FG5) which are located in further installations (A) different from the installation (A).Method according to Claim 1, wherein the further properties contain information relating to a geographical position of the field device (FG1,..., FG5) and / or relating to a measurement point (MS1, MS2) in which the field device (FG1,..., FG5) is installed, and / or relating to a function of the field device (FG1,..., FG5) in a measurement point (MS1, MS2) in which the field device (FG1,..., FG5) is installed.Method according to Claim 1 or 2, wherein the further properties are transmitted from the field devices (FG1,..., FG5) to the service platform (SP) or to the gateway (GW) and / or wherein the further properties are stored on the service platform (SP).Method for compensating a malfunction of a field device (FG1, FG2, FG3, FG4, FG5) in a plant (A) in automation technology, wherein a multiplicity of field devices (FG1,..., FG5) are present 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 gather at least one process variable, wherein the field devices (FG1,..., FG5) are incorporated in a first communication network (KN1) and communicate with a superordinate unit (SPS), wherein the field devices (FG1,..., fg5) each transmit the at least one elevated process variable to the superordinate unit (SPS) via the first communication network (KN1), and wherein the superordinate unit (SPS) transmits the elevated process variables to a control center (LS) of the installation (A), comprising: - transmitting the process variables of the field devices (FG1,..., FG5) to a service platform (SP) by means of a gateway (GW); - generating history data on the basis of the transmitted process variables for each of the field devices (FG1,..., FG5); establishing a replacement system (ES) on the basis of the history data, wherein the service platform (SP) or an application running on the service platform (SP) or the gateway (GW) determines, during the establishing of the replacement system (ES), which process variable of a sensor unit (SE 1,..., SE 5') can replace a process variable of a further sensor unit (SE 1,..., SE 5') with a predetermined accuracy as a replacement variable; transmitting the device status of the field devices (FG 1,..., FG 5) and / or of the sensor units (SE 1,..., SE 5') to the gateway (GW); and - transmitting the replacement variable to the control center (LS) by means of the superordinate unit (SPS) in the event of at least one predetermined device status of a field device (FG1,..., FG5) or of a sensor unit (SE1,..., SE5'), characterized in that the service platform (SP) or the application running on the service platform (SP) or the gateway (GW) compares the history of the replacement variable with the history data of the field device (FG1,..., FG5) or of its sensor unit (SE1,..., SE5') which has the predetermined device status and determines a deviation of the replacement variable from the history data.Method according to Claim 4, wherein the superordinate unit (SPS) corrects the replacement variable in real time by the determined deviation.Method for compensating a malfunction of a field device (FG1, FG2, FG3, FG4, FG5) in a plant (A) in automation technology, wherein a multiplicity of field devices (FG1,..., FG5) are present 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 gather at least one process variable, wherein the field devices (FG1,..., FG5) are incorporated in a first communication network (KN1) and communicate with a superordinate unit (SPS), wherein the field devices (FG1,..., fg5) each transmit the at least one elevated process variable to the superordinate unit (SPS) via the first communication network (KN1), and wherein the superordinate unit (SPS) transmits the elevated process variables to a control center (LS) of the installation (A), comprising: - transmitting the process variables of the field devices (FG1,..., FG5) to a service platform (SP) by means of a gateway (GW); - generating history data on the basis of the transmitted process variables for each of the field devices (FG1,..., FG5); establishing a replacement system (ES) on the basis of the history data, wherein the service platform (SP) or an application running on the service platform (SP) or the gateway (GW) determines, during the establishing of the replacement system (ES), which process variable of a sensor unit (SE 1,..., SE 5') can replace a process variable of a further sensor unit (SE 1,..., SE 5') with a predetermined accuracy as a replacement variable; transmitting the device status of the field devices (FG 1,..., FG 5) and / or of the sensor units (SE 1,..., SE 5') to the gateway (GW); Transmission of the replacement variable to the control centre (LS) by means of the superordinate unit (SPS) in the event of at least one predetermined device status of a field device (FG1,..., FG5) or of a sensor unit (SE1,..., SE5'), wherein the service platform (SP) or the application running on the service platform (SP) or the gateway (GW) calculates an evaluation of the determined replacement variable, characterized in that the evaluation of the replacement variable is made known to an operator before the transmission of the replacement variable and in that the replacement variable is transmitted only if the operator confirms it.Method according to Claim 6, wherein the set of the history data of the field device (FG1,..., FG5) or its sensor unit (SE1,..., SE5') which has the predetermined device status is included in the calculation of the evaluation.

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