METHOD FOR CHECKING LOAD CIRCUITS IN A TECHNICAL PLANT

Description

Technical Gebiet

[0001] The present invention relates generally to the field of electrical engineering, in particular to the field of power electronics and power electronic circuits. Specifically, the present invention relates to a method for testing load circuits of a control system in a technical plant. This control system comprises at least two load circuits, at least one control unit, and a switched-mode power supply. The switched-mode power supply provides a supply voltage and / or a supply current to the at least two load circuits, each of which has at least one load unit (e.g., sensor, actuator, relay, contactor, solenoid valve, servo motor, etc.). For this purpose, the at least two load circuits are connected to at least two output channels, which are formed either by at least two direct outputs of the power supply or by two externally connected, separately switchable output branches.The control unit provides control signals for controlling at least two output channels. Stand der Technik

[0002] Nowadays, complex machines and / or systems are used in many areas, such as industrial production and manufacturing, energy generation and distribution, automation technology, building management, etc. A system is understood as a planned assembly of spatially related components (e.g., machines, devices, and / or apparatus) that are functionally, control-technically, and / or safety-technically linked. Such technical systems, such as production plants, manufacturing plants, energy generation and distribution systems, etc., and their components are becoming increasingly complex.For the efficient operation of technical systems and complex machines, control systems are typically used. These systems use sensor or measuring units to measure operating or process parameter values ​​of the system or machine. Based on these measured values, actuators or load units (e.g., contactors, solenoid valves, optical or acoustic warning signals, motor units, display units, etc.) are then controlled to modify operating or process parameters. The control system aims to enable the machine or system to operate as autonomously as possible, independent of human intervention.

[0003] The control system typically includes a control unit for evaluating the measured values ​​from the sensor or measuring units and for controlling the actuator units (e.g., servo motor, warning signal, display unit, etc.). The control unit can also be used to switch various load units, such as contactors, solenoid valves (actuated by an electromagnet), etc., on or off according to process requirements. A programmable logic controller (PLC), a microcontroller, or an industrial PC can be used as the control unit.

[0004] Furthermore, such a control system includes at least one switched-mode power supply (such as a switching power supply) that converts an unregulated input voltage—usually an AC voltage—into a constant output voltage—usually a DC voltage (e.g., 24 volts)—to supply the control system's load components. Such a power supply—such as the Siemens SITOP PSU8600—can, for example, have at least two or more outputs for directly connecting load circuits. These outputs are used as output channels and can be controlled by control signals from the control unit. Alternatively, a switched-mode power supply can be used, to which, for example, a module (e.g., a switchable fuse, etc.) can be connected via one of the power supply's outputs. This module would then provide, for example, at least two separately switchable output branches as output channels.Each output channel can be connected to a load circuit with at least one load or load unit, or with a group of load units. The load or load circuit is then supplied via the respective output channel with a supply voltage (e.g., 24 volts) and / or a supply current provided by the power supply. To control the output channels—that is, to switch the voltage and / or current of a load circuit on or off—the control unit can provide control signals, e.g., to the power supply, or it can control the output channels and influence the supply voltage or current in the output channels (i.e., the supply voltage or current for the respective connected load circuit).

[0005] With a power supply featuring at least two output channels, voltage and current can be individually set and monitored for each channel. For example, the supply or load current, or alternatively the voltage, for each connected load circuit can be measured and monitored. This allows, for instance, the determination of current consumption or voltage in the respective load circuit. Control and switching operations by the control system's control unit can alter the current consumption or voltage in each load circuit. This means that switching load units (such as contactors or solenoid valves, etc.) on and off according to process requirements in the plant or machine can change the current consumption in each load circuit.

[0006] After the installation, expansion, etc., or commissioning of a complex machine or system, checking for errors is an essential aspect to ensure smooth and safe operation. In particular, it is important to identify so-called wiring errors in the system or in the system's control system. dh To detect errors when connecting one or more load units to a load circuit or an output channel of the power supply in a timely manner, in order to enable proper operation in the system or machine and to protect load units, especially sensor and / or actuator units, from damage or destruction.

[0007] A common method for checking wiring is, for example, the so-called "continuity test" or "testing for continuity" using a continuity tester before commissioning a system or during a test phase. A continuity tester is an electrical testing device that indicates, via a visual or audible signal, whether an electrical connection exists between two points. With a continuity tester, for example, the individual connections between a power supply output channel and a load unit in a load circuit of the machine's or system's control system can be checked – usually manually – for correct wiring. However, this method is not very time-consuming and is also prone to errors, especially with complex machines and / or systems with multiple control system load circuits.

[0008] Another way to check whether the wiring of the control system of a plant or machine has been carried out correctly is offered by zB Automated connection testers, which are connected, for example, via test combs to terminal blocks in a control cabinet of the plant or control system, then perform connection checks according to the plant's circuit diagram. However, such a connection tester is rather expensive to purchase and requires zB a dedicated test program, which must be tailored to the system or machine. In particular, the specific test program for the continuity tester may be required. zB When expanding, modifying, etc., the connection tester can hardly be reused or requires extensive adaptation. Furthermore, while a connection tester checks the connections within the system, it does not check the functionality of the connected system components.

[0009] However, it is also possible, for example, to detect wiring errors only during or after the commissioning of a system or machine. During the commissioning of a system or machine, zB One load circuit of the control system after another is activated, and the function of the load units connected to each load circuit is checked. However, this check is performed even with a normal operating voltage in the respective load circuit, and the load circuit is usually only protected by normal operating voltage. Therefore, if there is a wiring error in connected load units, such as... zB Sensor or actuator units, which may be damaged or destroyed. Furthermore, it is very difficult in this way to verify the accuracy of load units used in the system or the system's control system. zBto detect false signals or system malfunctions. That is, if zB an incorrect type of proximity switch was installed or zB a sensor has been assigned to the wrong load circuit.

[0010] Furthermore, zBThe REX system from ETA Elektrotechnische Apparate GmbH is a modular power distribution and protection system for the centralized monitoring of decentralized systems. This system comprises at least one feed-in module for connection to a switched-mode power supply and at least one protection module with one or two channels for connecting and protecting a load circuit. The feed-in module can, for example, determine dynamic system information and measured values ​​(e.g., current voltage and current values ​​in load circuits connected via one or more protection modules, the reason for a protection module tripping, etc.) and read this information from a higher-level control unit via a data connection. Furthermore, a nominal current and a limit value for a specific current value in the load circuit can be set for the protection modules.While this power distribution and protection system can detect extreme defects such as short circuits in the wiring of a load circuit, short circuits, or overcurrents in a load circuit—especially during operation—it is very difficult, if not impossible, to detect wiring errors that may only lead to minor overcurrents or current dips compared to a target state, as well as the use of an incorrect load unit in a load circuit (e.g., incorrect proximity switch type, incorrectly assigned sensor or actuator on the supply and / or signal side, etc.) without targeted, time-consuming manual troubleshooting or data analysis by a user. Furthermore, the at least one fuse module limits the supply voltage range in the load circuit to the typical operating voltage range of the respective components, since the fuse module, for example,Due to an operating voltage monitoring system, it can only be switched on from an operating voltage of approximately 16 volts. Furthermore, the modular design of the system can lead to increased effort and costs, for example, in system planning and maintenance.

[0011] From European patent EP 2 313 952 B1, an electrical installation and a method for operating this installation are known. The installation comprises a supply circuit with at least one permanently wired load, which is protected by a protective device. A control unit determines and stores maximum current values ​​for observation intervals in order to derive limit values ​​for adjusting a trip parameter. While the electrical installation and the associated method known from EP 2 313 952 B1 ensure that an undetected excessive tripping value of the protective device is adjusted accordingly during initial commissioning and / or during operation, thereby increasing the reliability of the installation, it does not detect whether the at least one load or its associated load circuit is correctly wired.

[0012] Furthermore, German patent application DE 10 2018 114 094 B3 discloses an output module for an industrial control system and a method for implementing such a system. In this system, a sensor unit acquires current and voltage values ​​from a connected load, which are then processed in a computing unit using applications to determine physical states related to the load (e.g., load temperature, short-circuit, cable break, and / or winding short-circuit detection, wear detection). The applications are selected from a set of available applications and loaded via a program memory. The resulting evaluation is then transmitted to a control unit, a higher-level control system, and / or an external data storage device.In the industrial control system and a method for implementing industrial control systems disclosed in document DE 10 2018 114 094 B3, defects such as... can occur during the operation of a plant. zBShort circuits, cable breaks, overheating, etc., as well as signs of wear on a load, especially a valve coil, a piezo actuator, a valve, etc., can be detected, provided the corresponding application for evaluating currently recorded current and voltage values ​​is available. Wiring errors, which may only lead to minor overcurrents or current dips compared to a target state, as well as the use of an incorrect load unit in a load circuit (e.g., incorrect proximity switch type, incorrectly assigned sensor or actuator, on the supply and / or signal side, etc.), can be detected without targeted, time-consuming manual troubleshooting or data analysis by a user or by implementing a corresponding application for a self-test phase of the system. zB Before commissioning, it is very difficult or almost impossible to detect.

[0013] Furthermore, an overload protection method is known from EP 1 837 971 B1, in which an overload condition is generated for an output module that controls a load. The load current and voltage are monitored at sampling intervals and compared with a predetermined load current threshold. Ramp-shaped load voltage values ​​are generated for reference purposes, depending on the initial load voltage and a predetermined load voltage step size, as long as an overload timer is running and the load current exceeds the load current threshold. Even with this method, wiring errors in a system are very difficult or even impossible to detect. Darstellung der Erfindung

[0014] The invention is therefore based on the objective of providing a method for checking load circuits of a plant or a control system of a plant, by which wiring errors and / or the use of an incorrect load unit in a load circuit of the plant or an incorrectly assigned signal unit can be detected in a simple way and without the use of additional test equipment or time-consuming manual search.

[0015] This problem is solved by a method of the type mentioned at the outset, having the features according to the independent claim. Advantageous embodiments of the present invention are described in the dependent claims.

[0016] According to the invention, the problem is solved by a method for checking load circuits of a control system of a plant of the type mentioned above, wherein the control system comprises, in addition to at least two load circuits, each of which has at least one load unit or consumer (e.g., contactor, solenoid valve, sensor unit, actuator unit, etc.), at least one control unit and a switched-mode power supply. The switched-mode power supply provides the at least two load circuits, each with at least one load unit, with a supply voltage and / or a supply current via at least two output channels, wherein the at least two output channels can be formed by at least two direct outputs of the power supply or by at least two output branches of a module connected to the power supply. Furthermore, the output channels are controlled by means of control signals from the control unit.The method according to the invention comprises at least the following steps: . Determining reference current values ​​at predefined supply voltage values ​​or reference voltage values ​​at predefined supply current values ​​for predefined system states, wherein at least one output channel is switched on for a given system state and the respective load circuit of the control system is supplied by the supply voltage with the predefined voltage values ​​or by the supply current with the predefined current values; storing the reference current values ​​determined for the predefined system states or the reference voltage values ​​determined for the predefined system states; measuring current values ​​at the respective predefined supply voltage values ​​or current values ​​at the respective predefined supply current values ​​at the at least one switched-on output channel for the respective currently predefined system state during a self-test phase;Check whether, under one of the specified system states, a specified tolerance range is exceeded when comparing the currently measured current values ​​with the corresponding stored reference current values ​​at at least one of the specified supply voltage values, or when comparing the currently measured voltage values ​​with the corresponding stored reference voltage values ​​at at least one of the specified supply current values; and display the associated load circuit if, under one of the specified system states, an exceedance of the specified tolerance range is detected at at least one of the specified supply voltage values ​​or at at least one of the specified supply current values.

[0017] The main aspect of the solution proposed according to the invention is that it makes it possible to perform very precise detailed measurements in load circuits of a plant or complex machine, or of the control system belonging to the plant or machine, in a simple manner and without the use of a test device (e.g., continuity tester, connection tester, etc.), and to evaluate the wiring and the correctness of the load units connected to the respective load circuit. The method according to the invention facilitates and simplifies the detection of so-called hidden wiring faults in a simple manner and without manual searching or detailed data analysis by, for example, a user.

[0018] An error in the wiring of the control system of the plant or machine can lead to a change in the magnitude of the current consumption and thus the load current in the corresponding load circuit, or, in the case of a specified or impressed current, to voltage changes. Similarly, effects can occur in the load circuit to which a load unit has been incorrectly connected. For example, if a load unit (e.g., sensor, actuator, etc.) is incorrectly wired, the current consumption in the load circuit to which it is assigned according to the circuit diagram may be lower than the determined reference current values, while the current consumption in the load circuit to which the load unit was incorrectly connected may be higher than the determined reference current values.

[0019] In the method according to the invention, predefined system states are generated during a self-test phase or during test operation of the system or machine. Reference current or voltage values ​​were determined for these system states and stored as comparison values. A system state describes an operating state of the system or machine and can be generated, for example, via the control unit by appropriately controlling—i.e., switching on and off—the output channels. This means that in a predefined system state, at least one load circuit is activated. The at least one associated load unit of the load circuit is supplied with a supply voltage or current via the respective output channel, whereby the supply voltage assumes predefined voltage values ​​or the supply current can be impressed.Then, at least one output channel that is switched on in the currently specified system state, a current value of the load current in the respective load circuit is measured for each of the specified supply voltage values. By comparing the currently measured current values ​​of the respective system state with the corresponding reference current values, conclusions can be drawn about the correct wiring of the load circuit or the at least one load unit and, if applicable, about the proper or intended functioning of the at least one load unit. Alternatively, a current voltage value can be determined at at least one output channel that is switched on in the currently specified system state for each of the specified or impressed current values ​​of the supply current in the corresponding load circuit.The currently measured voltage values ​​of the respective system state are then compared with the corresponding reference voltage values ​​at the respective, specified, impressed current values ​​of the supply current, and conclusions are drawn from this comparison regarding the wiring of the respective load circuit. For example, faulty wiring of the load circuit and / or an incorrectly installed or mounted load unit can thus be detected very easily, quickly, and, if necessary, automatically. zB Predefined system states are run through in the form of a test program - and are detected.

[0020] As a further expedient development of the method according to the invention, it is provided that, for the respective predefined system states, reference voltage values ​​are determined and stored for those output channels and thus for those load circuits which are switched off or disconnected in the respective predefined system state. Furthermore, during the self-test phase, current voltage values ​​for the output channels or load circuits that are switched off or disconnected in the respective system state are measured and then compared with the reference voltage values ​​corresponding to the respective system state. If a predefined tolerance range is exceeded when comparing measured voltage values ​​and corresponding reference voltage values ​​for the respective system state, the corresponding load circuit is displayed. By measuring a voltage at a switched-off or disconnected load circuit, the system determines the appropriate load circuit.With the load circuit switched off, the correctness of the wiring of the system or machine, or the associated control system, can also be easily assessed and verified. For example, voltage values ​​measured at switched-off output channels or output branches in a given system state can indicate faulty wiring in the corresponding load circuit.

[0021] Additionally, it can be useful to determine and store reference current values ​​for at least those output channels that are switched off in each predefined system state. During the self-test phase, current values ​​are then measured for these switched-off output channels and compared with the corresponding reference values. The respective load circuit is then displayed if a predefined tolerance range is exceeded when comparing the measured current values ​​with the corresponding stored reference current values. Current flow in a load circuit that is switched off in the respective system state can also be used to detect wiring errors or to assess the proper functioning of the respective load circuit or the control system of the system or machine.

[0022] The reference current and voltage values ​​for the respective system states can ideally be determined during the planning and development phase of the system or machine using a reference system, for example, at the manufacturer's site. This then provides reference current and, if necessary, reference voltage values ​​at the respective installation site during the commissioning of systems or machines of the same type (e.g., series production). These values ​​can be used to verify that the load circuits have been wired correctly and that the correct load units have been installed at the planned locations or in the planned load circuits.

[0023] Alternatively or additionally, the reference current and voltage values ​​for the respective system states can be determined during a commissioning phase of the system under test (e.g., during test commissioning at the manufacturer's site, etc.) or derived from current and voltage values ​​that are continuously measured at the respective output channels for different system states during operation of the system or machine. Ideally, the reference values ​​are derived from previous measurements taken under various system states (e.g., during operation, commissioning at the manufacturer's site, or at the user's site). This is particularly useful if a system or machine is partially disassembled, transported, and reassembled. Upon recommissioning or restarting, the correct wiring of the system's load circuits can then be verified.The proper functioning of the machine control system and the load circuits can be checked very easily.

[0024] A further advantageous development of the method according to the invention provides that, for each predefined system state, reference values ​​of parameters and / or signals at the inputs of the control unit are acquired and stored. During the self-test phase, current values ​​of the parameters and / or signals at the inputs of the control unit are queried for each predefined system state and compared with the corresponding reference values. If the comparison between the current values ​​of the parameters and / or signals and the respective stored reference values ​​of the parameters and / or signals shows that a predefined tolerance range is exceeded, the respective load circuit can be displayed. Such parameter and / or signal values ​​can zBThese values ​​could include a temperature sensor reading, a proximity switch idle signal, a speed sensor reading, a steam pressure reading, a function signal, etc. This also makes it very easy to identify wiring errors in the system or machine.

[0025] It is advantageous if the specified tolerance range for comparing currently measured current and / or voltage values ​​with the corresponding reference current and / or voltage values ​​can be adjusted. Ideally, the adjustable tolerance range allows for the compensation of fluctuations in current and / or voltage measurements, as well as slight drifts. zB to prevent unnecessary alarms. By regularly performing the method according to the invention, typical fluctuations in the load circuits of the system or machine can, for example, be detected and the tolerance range adjusted accordingly. um zBTo avoid pseudo-errors caused by a tolerance range that is too narrow or overlooking errors caused by a tolerance range that is too wide.

[0026] The specified tolerance range can be expressed, for example, as a percentage or as an absolute value. A combination of both is also possible. Furthermore, a single tolerance range can be specified for all load circuits to be checked, or specific tolerance ranges can be defined for individual load circuits.

[0027] Ideally, the respective system states and thus the output channels that are switched on and off are monitored. dhThe control unit specifies the on / off outputs of the power supply, the externally connected output branches (both switched on and off), and the voltage values ​​for the supply voltage of the respective output channel or the current values ​​for the supply current of the respective output channel. This is determined by the control unit, which zB Since it can be implemented as a programmable logic controller (PLC), a microcontroller or an industrial PC, at least a majority of the load units can be controlled. dh They can be selectively activated and deactivated. Therefore, the control unit can also create very simply defined, predefined system states, in which zBIndividual load units or load circuits are active, while the remaining load units of the control system are deactivated. Furthermore, the control unit can have a data connection to the power supply. This allows the control unit to forward control signals to the switched-mode power supply for setting predefined system states. The switched-mode power supply then... zB The corresponding output channels or output branches, and thus the connected load circuits and load units, are switched on or off according to the specified system state. Additionally, the control unit can also specify the voltage values ​​for the supply voltage or current values ​​for the supply current for the respective system state, or these values ​​can be set at the externally connected output branch.

[0028] It is advantageous to include a predefined waiting period between changing the specified supply voltage or supply current value for the respective specified system state and determining the reference current or reference voltage value, as well as the current measurement for that specified supply voltage or supply current value. This simple method allows, for example, the influence of fluctuations in current consumption or voltage, caused by switching on the supply voltage to the respective load circuit (i.e., switching on the corresponding output channel), by changing the supply voltage, or by changing the supply current value due to the respective load units in the load circuit, to be mitigated.The current measured values ​​(current or voltage) should be eliminated as far as possible. The predefined waiting time can, for example, be chosen so that a stable current value is reached for measuring the current values ​​in the respective load circuit, which... zB exhibits a relatively small fluctuation (e.g., 3% deviation in one second). A preset value for the configurable waiting time for the respective load circuits or corresponding load units can be defined. zB These values ​​are determined during the process of establishing reference values ​​for current or voltage and then used in the self-test phase. This allows for... zB Reduce waiting times for load units or load circuits with negligible settling time to a minimum. For load units with relatively long settling times, a safety margin can be added to the predefined waiting time to ensure stable measured values.

[0029] Furthermore, it is also conceivable to calculate a reference current value and / or current measurement value as an average of several current measurements taken over a predefined integration time (e.g., 0.1 seconds, 10 seconds, etc.), or to employ another type of mathematical filtering to reduce the influence of current consumption fluctuations—especially when the supply voltage changes—in the load circuit or noise during the determination of the current measurements. Additionally, when the reference current values ​​are initially recorded, a transient response to changes in the supply voltage (i.e., switching on the supply voltage in the respective load circuit or changing the voltage value of the supply voltage) can be also determined. The temporal change or...The transient process can be characterized, for example, by a temporal sequence of reference current values ​​or by recording the trend, thus enabling the mapping of a temporal reference current profile of the transient process. A similar approach – e.g., mathematical filtering – is also conceivable for determining the reference voltage values, such as the current voltage measurements, in order to reduce or eliminate transient processes, for example, when switching on or changing the supply current.

[0030] It is also advantageous if the specified voltage values ​​for the supply voltage are increased in predefined voltage steps from an output supply voltage (e.g., 0 volts) up to a predefined nominal voltage (e.g., 28 volts) or an operating limit of at least one load circuit unit connected to the respective load circuit. By increasing the supply voltage in predefined voltage steps (e.g., in 2-volt increments), load circuit-specific and / or current values ​​typical for the respective load unit can be measured, providing additional support in locating wiring errors and potential malfunctions. For example, small sensors can incorporate a linear regulator with internal electronics that activates the sensor only above a certain supply voltage (e.g., 5 volts or 12 volts) and maintains it up to a certain voltage (e.g., 28 volts).a constant current draw. Higher-power consumers, such as control units, etc., have, for example, a buck converter, etc., to generate an internal auxiliary voltage and reduce the current as the supply voltage increases. A contactor as a load unit, for example, exhibits a linearly increasing current draw with increasing supply voltage. A DC motor, for example, can have very low resistance at low voltage and draw a high current, which, for example, increases in a flat curve as rotation begins or can even decrease.

[0031] As an alternative to a stepwise or incremental increase of the supply voltage at the at least one switched-on output channel of the power supply, it can also be advantageous to increase the specified supply voltage values ​​as a linear voltage ramp with a predefined slope from an output supply voltage (e.g., 0 volts) to a specified nominal voltage (e.g., 28 volts) or an operating limit of the at least one load circuit unit connected to the respective load circuit. Additionally, a rate of increase of the supply voltage can also be specified. The current values ​​in the at least one active load circuit of the respective system state are then measured synchronously with the increase of the supply voltage. To accelerate, for example, the throughput time of the process can be adjusted depending on the respective load unit or...Different rise rates can be selected for the respective load units in the load circuit for different supply voltage ranges. For example, if it is known that a consumer or load unit in a load circuit is only switched on within a supply voltage range of 14 to 16 volts, the voltage range up to 14 volts can be traversed more quickly (i.e., with a higher rise rate). For the voltage range above 14 volts, a lower rise rate is then selected, for example, to determine the actual switch-on voltage of the load unit, to ascertain the corresponding current measurements, and to detect any wiring errors, etc.

[0032] The determined reference current values ​​and, if applicable, the determined reference voltage values ​​can be stored in the control unit of the plant or machine control system.

[0033] This allows the control unit to execute the inventive method – for example, in the form of a test program. In addition to specifying the system states to be traversed, the control unit can zB also check if zB in Sensor units attached to load circuits return measured values ​​when the respective load circuit is activated. These measured values ​​or sensor signals can be stored in addition to the reference current and / or voltage values ​​and offer an additional verification option during the self-test phase of the system or machine, ensuring correct wiring and proper functioning, especially of sensor units in the control system.

[0034] Alternatively or additionally, the determined reference current values ​​and, if applicable, the determined reference voltage values ​​can be transmitted to and stored in an evaluation and / or data processing unit – usually designed as a central or higher-level unit. This allows the reference values ​​to be used very easily for checking several identical systems or machines.

[0035] Furthermore, it is advantageous if the predefined system states can be selected via the evaluation and / or data processing unit. This allows zB A simple test program can be created for the self-test phase of the system or machine, which zBThis process is carried out during commissioning at the user's site of the system or machine. During the selection process, system states can be removed from the test program or excluded if they have proven unsuitable for verification based on repeated test program runs. This can accelerate the verification process, as only relevant system states can be selected. Additionally, zB For the selection, a list of plant states (such as zB (Activation of a pump or valves) can be specified, which, for example, does not have counterproductive, dangerous or undesirable system conditions, or ideally, these system conditions can be excluded during the selection process.

[0036] The currently measured current values ​​and, if applicable, the measured voltage values ​​for the respective system state can then also be forwarded to the evaluation and / or data processing unit and stored there. Storing the current measured values ​​very easily enables expanded analysis and evaluation options. Furthermore, measurement results can be easily displayed graphically, or developments over time within the system or machine can be assessed. In this way, for example, impending malfunctions in load circuits or changes that could lead to malfunctions in the system or machine can be detected in a timely manner. Kurzbeschreibung der Zeichnung

[0037] The invention is explained below by way of example with reference to the accompanying figures. These show: Figure 1a schematic and exemplary structure of a control system of a plant for carrying out the inventive method for checking load circuits Figure 2 an exemplary sequence of the inventive method for checking load circuits of a control system in a plant. Ausführung der Erfindung

[0038] Figure 1This schematically illustrates an example of a control system for a technical plant or complex machine. The exemplary control system includes at least one control unit (SE), which can be implemented, for example, as a programmable logic controller (PLC). Alternatively, a microcontroller or an industrial PC can also be used as the control unit SE. The control unit SE has digital outputs O1, ..., O4 for controlling load units—for example, for switching switching units S1, ..., S4. Alternatively, the switching units S1, ..., S4 can also be part of an output module of the control unit SE, in particular a digital output module with a programmable logic controller (PLC). Alternatively or additionally, the control unit SE can also have analog outputs to which, for example, actuator units or switching units can be connected. Figure 1For the sake of simplicity, the analog outputs of the SE control unit are not explicitly shown. The digital outputs O1, ..., O4, as well as the analog outputs, allow the SE control unit to control the system or machine, especially during operation, and thus regulate or establish operating states. Furthermore, the SE control unit features, for example, digital inputs I1 and I2, which can receive signals from load units—particularly sensor units DS and AS. The signals received at inputs I1 and I2 provide the SE control unit with information about current events in the system or machine, and can trigger specific control processes. The SE control unit may also have analog inputs for connecting and querying sensor units.

[0039] The example control system further includes, for example, a switched-mode power supply (SV), which is connected via an input (IN) to a voltage supply (U AC, e.g., a three-phase AC voltage). The power supply SV has, for example, eight outputs and thus eight output channels (A1, ..., A8), to which the load circuits of the control system are directly connected. These load circuits of the control system for the plant or machine are supplied with a supply voltage (e.g., 24 V DC) and a supply current from the power supply SV. The power supply SV can, for example, offer the capability, such as the SITOP PSU8600, of individually setting and monitoring the voltage and current supplied to the load circuit for each output channel (A1, ..., A8).

[0040] Alternatively, the control system can also have a power supply (SV) to which an external module (e.g., an externally switchable fuse unit, etc.) with at least two output branches is connected. These output branches then form the at least two output channels A1, ..., A8 for the power supply SV. These output branches or output channels A1, ..., A8 can be switched independently, and the voltage and current supplied to the load circuit can be individually set and monitored. The respective load circuits or the load units associated with the load circuits are then supplied with current or voltage via output channels A1, ..., A8.

[0041] At the in Figure 1In the exemplary control system shown, a supply voltage is specified for the respective output channel A1, ..., A8 in the respective load circuit. The current drawn by at least one load unit in the respective load circuit thus forms a measurable quantity for the reference values ​​and for the current measured values ​​for a given system state. Alternatively, the power supply SV, or at least one output channel A1, ..., A8 of the power supply SV, can be operated as a current source. In this case, a supply or load current is specified or applied as a setpoint to the respective output channel A1, ..., A8. A voltage is then determined for the reference values ​​or measured as the current measured value for the respective system state. This voltage adjusts itself depending on the impedance of the respective load unit in the load circuit and can potentially be measured with higher accuracy.is easier to measure with loads that have a capacitive component or with capacitors.

[0042] Furthermore, the power supply (SV) and the control unit (SE) of the control system can have interface modules (DV) via which, for example, a bidirectional data connection can be established for transmitting control signals and data information. For the data connection, Profinet (Process Field Network) – an open industrial Ethernet standard of the PROFIBUS user organization – can be used, for example.

[0043] For a power supply to the control unit SE, - as exemplified in Figure 1 depicted - a separate power supply, which is in the Figure 1Not shown, but provided for. Alternatively, the control unit SE can also be supplied with the corresponding supply voltage from the switched-mode power supply SV of the control system. For this purpose, the control unit SE could, for example, be connected to a first output channel A1 of the power supply SV.

[0044] The load circuits of the plant or machine's control system are connected to output channels A1, ..., A8, each of which can have at least one load unit – e.g., at least one actuator, switching unit, or sensor unit. In the case of the Figure 1In the exemplary control system shown, switching units S1, S2, S3, S4 and their associated load resistors R1, R2, R3, R4 are connected to the first output channel A1 and a second output channel A2. These units can be switched on or off via the respective switching units S1, S2, S3, S4 and by means of control via the respective digital outputs O1, O2, O3, O4 of the control unit SE. Further actuator or switching units S5, S6 (e.g., contactors, solenoid valves, etc.) are also connected as load units to a third and fourth output channel A3, A4. These actuator or switching units S5, S6 can be controlled, for example, by the control unit SE of the control system or by another control unit.

[0045] For example, a light signal LS and a motor M are connected to a fifth output channel A5 of the power supply SV. zB It is connected to operate a fan unit. A sixth output channel, A6, of the power supply SV is connected. zB An additional load resistor R5 is connected. For example, the motor M or the fan unit is incorrectly not connected to ground via the fifth output channel A5 – as shown by the dashed line – but is instead connected to the sixth output channel A6 due to a wiring error VF1 (e.g., during the assembly of the system or machine). The wiring error VF1 is shown as a dash-dotted line.

[0046] A second exemplary wiring error, VF2, is shown in the wiring of the seventh and eighth output channels A7 and A8 of the power supply SV. The seventh and eighth output channels A7 and A8 are... zBEach load unit has a sensor unit DS, AS connected, from which, for example, an input signal is supplied to the corresponding digital input I1, I2 of the control unit SE. With correct wiring – again shown by a dashed line – the seventh output channel A7 would be connected. zBA pressure sensor DS is connected, which, upon reaching a threshold, sends an input signal to the digital input I2 of the control unit SE. An acoustic signaling unit AS is connected to the eighth output channel A8, which outputs a function signal to the digital input I1 of the control unit SE during operation. Due to the second wiring error VF2 – as shown by the dashed-dotted line – the connections of the two sensor units DS and AS were reversed. As a result, the acoustic signaling unit AS now receives its supply voltage via the seventh output channel A7, and the pressure sensor DS via the eighth output channel A8. However, the respective signal outputs of the pressure sensor DS and the acoustic signaling unit AS are connected to the correct digital inputs I1 and I2 of the control unit SE.

[0047] The Figure 2This shows an exemplary sequence of the inventive method for checking load circuits in a plant or a control system of a plant, as exemplified in Figure 1 depicted.

[0048] In carrying out the method according to the invention, system states are specified, particularly in a reference value determination step 101 for determining reference current and, if applicable, reference voltage values ​​in the respective output channels A1, ..., A8 of the power supply SV, and in a measurement step 103, in which current current values ​​and, if applicable, current voltage values ​​in the respective output channels A1, ..., A8 of the power supply SV are determined. These system states are triggered, for example, by control commands from the control unit SE, by which output channels A1, ..., A8 of the power supply SV are switched on or off, for example, by the power supply SV itself, and, if applicable, outputs O1, ..., O4 of the control unit SE are activated or deactivated. Additionally, for specified system states, inputs I1, I2 of the control unit SE can also be queried, for example, for pending parameter values ​​or signal values ​​from sensor units DS, AS.

[0049] A predefined system state is defined as an operating condition of the system or machine, which is determined by a switch position of the control unit SE and activated load circuits (i.e., those supplied with voltage). This means that for a system state, at least one of the output channels A1, ..., A8 of the power supply SV is activated or switched on, and the corresponding load circuit is supplied with voltage by the power supply SV. Additionally, if the activated load circuit is controlled by a load unit S1, ..., controlled by the control unit SE, S4The corresponding output O1, ..., O4 of the control unit SE is activated, or if the actively switched load circuit has a sensor unit DS, AS, the corresponding input I1, I2 of the control unit is queried. Such inputs (e.g., temperature values, speed values, steam pressure values, function signals, etc.) can also be used, for example, to check the load circuit—in particular, the correct wiring of a sensor unit DS, AS. This means that specific switch positions and parameters are available for the respective system state, especially in the control unit SE. Ideally, system states are defined for determining reference values ​​as well as current and voltage measurements in a load circuit, in which, for example, only one output channel A1, ..., A8 and, for example, only one output O1, ..., O4 of the control unit SE are activated simultaneously, provided that the corresponding load circuit has a load element S1, ..., S4 controlled by the control unit SE.

[0050] For the in Figure 1 An exemplary control system of a technical plant or machine, which is to be tested using the method of the invention, can thus, for example, define at least twelve functional plant states and, if necessary, zB These can be specified in the form of a test program. For these twelve functional system states, zBControl commands, sent from the control unit SE to the power supply SV via the data connection DV, activate one of the eight output channels A1, ..., A8 at a time. Additionally, one of the digital outputs O1, ..., O4 of the control unit SE is activated to switch on the corresponding switching unit S1, ..., S4 when the corresponding first or second output channel A1, A2 of the power supply SV is switched on. Thus, for an example of the first system state, the first output channel A1 is activated, while the remaining output channels A2 to A8 remain switched off. Then, for an example of the second system state, after the first output channel A1 is activated, the first digital output O1 of the control unit SE can also be activated to switch the first switching unit S1 in the load circuit connected to the first output channel A1 and to connect the corresponding load resistor R1.For an exemplary third plant state, the following remain. zB The first output channel A1 is switched on and the remaining output channels A2, ..., A8 of the power supply SV are switched off. Now, however, the first digital output O1 of the control unit SE is deactivated (i.e., the associated load resistor R1 is switched off) and the second digital output O2 of the control unit SE is activated to switch the second switching unit S2 in the load circuit connected to the first output channel A1 and to switch on the associated load resistor R2. Corresponding system states can also be implemented, for example, for the second output channel A2 of the power supply in the example shown in Figure 1 The system shown is predefined. In the remaining system states, for example, one of the output channels A3 to A8 of the power supply is switched on or activated in order to supply the corresponding load circuit with a supply voltage.

[0051] To reduce the test time, for example, several output channels A1, ..., A8 of the power supply SV and / or several outputs O1, ..., O4 of the control unit SE can be activated simultaneously. For the in Figure 1 The control system of a plant or machine depicted above could, for example, combine the second and third system states described above by simultaneously activating the first and second outputs O1, O2 of the control unit in addition to the first output channel A1 of the power supply SV, switching the associated switching elements S1, S2 in the load circuit connected to the first output channel A1 of the power supply SV, and simultaneously switching on the associated load resistors R1, R2. Similarly, the system states for the second output channel A2 of the power supply SV can also be combined.

[0052] In real-world systems, significantly more system states can be defined and used for the inventive method. However, counterproductive, dangerous, or impractical system states (e.g., a system state that unintentionally activates a pump or valve) can be excluded. Furthermore, the predefined or deemed useful system states can be compiled into a test program, which can be adapted, for example, for a self-test phase of a system or machine being commissioned by a user – i.e., the system states can be selected and predefined according to system and / or user requirements.

[0053] For the verification of the load circuits in a system according to the inventive method, reference current values ​​are determined in reference value determination step 101 for a predefined system state – i.e., with at least one output channel A1, ..., A8 of the power supply SV switched on – at predefined supply voltage values. This means, for example, that a predefined system state (e.g., the first system state with the first output channel A1 of the power supply SV switched on; the second system state with the first output channel A1 and the first digital output O1 of the control unit SE activated; etc.) is generated using the control unit SE. Then, for example, the predefined supply voltage values ​​of the associated load circuit are set at the at least one switched-on (e.g., the first) output channel A1 of the power supply SV, and the corresponding current values ​​are determined.Alternatively, in reference value determination step 101, instead of the reference current values ​​for a given system state – i.e., with at least one output channel A1, ..., A8 of the power supply SV switched on – reference voltage values ​​can be determined for given current values ​​of the supply current. This means, for example, that a given system state (e.g., the first system state with the first output channel A1 of the power supply SV switched on; the second system state with the first output channel A1 and the first digital output 01 of the control unit SE activated; etc.) is triggered using the control unit SE. Then, for example, the given current values ​​for the supply current of the associated load circuit are determined at at least one switched-on (e.g., the first) output channel A1 of the power supply SV. zB The voltage values ​​were imprinted by the power supply SV and determined.

[0054] In addition, voltage values ​​can also be determined as further reference voltage values ​​and / or current values ​​as further reference current values ​​at the remaining output channels A2, ..., A8, which are switched off in the specified system state, and the parameter and / or signal values ​​of the sensor units DS, AS can be queried as reference values, which are present at the inputs I1, I2 of the control unit SE.

[0055] The reference current values ​​can be determined, for example, using a reference system or machine. zB from a manufacturer in a development test phase (dh after successful development zB a series production system or machine). Alternatively or additionally, zBFor user-specific systems or machines, the reference current values ​​are determined during initial commissioning of the system or machine or derived from current values ​​measured during operation at the respective output channels A1, ..., A8 for the specified system states. Similarly, reference voltage values ​​for specified system states can also be determined on a reference system or machine, or during initial commissioning, or derived from voltage values ​​continuously measured during operation.

[0056] In storage step 102, the reference current values ​​determined for the specified system states and specified voltage values ​​of the supply voltage of the respective load circuit are stored. The reference current values ​​can then zBThe reference current values ​​are stored in the control unit SE of the plant's control system or transferred to the control unit SE of an identical plant or machine. Alternatively or additionally, the reference current values ​​can also be sent to a ne zB The values ​​can be transferred to and stored in a centrally available evaluation and / or data processing unit. If, for the specified system states, alternative reference voltage values ​​are determined for specified current values ​​of the supply current in the respective load circuit, or if additional reference voltage values ​​are determined at switched-off output channels A1, ..., A8, these can also be stored in the control unit SE. Alternatively or additionally, the reference voltage values ​​can also be transferred to the evaluation and / or data processing unit and stored there together with the corresponding reference current values. themStorage step 102 stores at least one reference current value for each specified system state, for each specified voltage value of the supply voltage in the respective load circuit, or a reference voltage value for each specified current value of the supply current in the respective load circuit.

[0057] Measurement step 103 starts a self-test phase on the system or machine being checked, which is carried out during commissioning. zB This process can be carried out after transport and reinstallation or a new installation of the respective system or machine, or even during a restart while the system or machine is running. In measurement step 103, the control unit SE then performs the following operations. zBThe predefined system states are triggered by commands sent via the data connection DV to the power supply SV and, if necessary, by signals at the outputs of the control unit SE to the load units S1, ..., S4 connected to it. The predefined system states can be selected, for example, from a list of possible or relevant system states for the system or machine. This list can zB created before or during reference value determination step 101 and zB be stored in the control unit SE or in the evaluation and / or data processing unit.

[0058] Furthermore, in measurement step 103, the specified voltage values ​​of the supply voltage at at least one switched-on output channel A1 are measured for each specified system state. ...,The current value is specified at output channel A8 of the power supply – for example, by the power supply SV via a command from the control unit SE. For each specified voltage value of the supply voltage, a current value is measured and stored at at least one activated output channel A1, ..., A8 of the power supply SV. This means that for each specified system state and each specified voltage value of the supply voltage, a current value is obtained, which can then be evaluated in relation to the corresponding reference current value.

[0059] To cycle through the specified supply voltage values ​​for the currently defined system state in measurement step 103, the supply voltage can, for example, be increased from an initial supply voltage (e.g., 0 volts) in predefined voltage steps (e.g., 2 volts) up to a predefined nominal voltage (e.g., 24 or 28 volts). Alternatively, the supply voltage can also be increased as a linear voltage ramp with a predefined slope or rate of increase from an initial supply voltage (e.g., 0 volts) up to a predefined nominal voltage (e.g., 24 or 28 volts), thus cycling through the specified supply voltage value. If the specified supply voltage value is reached at at least one switched-on output channel A1, ...If the voltage of output channel A8 of the power supply SV is changed either incrementally or by means of a ramp-like increase to the next predefined voltage value, a predefined waiting period can be provided between changing the voltage value of the supply voltage and measuring the current value in at least one switched-on output channel A1, ..., A8 of the power supply SV. In this way, current fluctuations caused by transient processes due to the voltage change, etc., are not measured, but rather a current value that is as static or constant as possible. Furthermore, it is possible to calculate an average of measured values ​​over a predefined integration time (e.g., 0.1 or 10 seconds) or to use other mathematical filtering to reduce current fluctuations and / or noise when determining the current values.The filtering can also be performed on several current measurements taken in a predetermined sequence in order to determine filtered measured values ​​over a predefined period (e.g. 1 minute) at predefined intervals (e.g. every 10 seconds) and thus be able to describe a transient process of a load unit or consumer.

[0060] For determining the reference values ​​of current or voltage in reference value determination step 101, the methods described above for changing the specified voltage values ​​of the supply voltage at at least one active output channel A1, ..., A8 can also be applied for the respective specified system state. A waiting period can also be provided between changing the voltage value of the supply voltage and determining the reference current value, or between changing the current value of the supply current and determining the reference voltage value. Alternatively, a filter method can be applied to reduce fluctuations and / or noise, e.g., from transient processes. It should be noted that in measurement step 103, the same methods for changing the voltage value of the supply voltage and for reducing current fluctuations (e.g., ...) can be used.Waiting time, mathematical filtering, multiple measurements in a predetermined sequence over a predetermined period at predetermined intervals, etc.) are used.

[0061] Additionally, in measurement step 103, current voltage values ​​can also be measured at the output channels A1, ..., A8 of the power supply SV, which are switched off in the respective specified system state. It is also possible to measure current values ​​at those output channels A1, ..., A8 of the power supply SV that are switched off in the respective specified system state. These currently measured voltage and current values ​​are also saved and can be used for evaluation and verification of the load circuits of the system or machine.

[0062] Alternatively, in measurement step 103, instead of the current value, the current voltage value can be measured at at least one switched-on output channel A1, ..., A8 for the respective predefined system state. For this purpose, the predefined current values ​​of the supply current are input at at least one switched-on output channel A1, ..., A8 for the respective predefined system state – e.g., by the power supply SV via a command from the control unit SE. For each predefined current value of the supply current, a current voltage value is then measured and stored at at least one switched-on output channel A1, ..., A8 of the power supply SV. This means that for each predefined system state, a current voltage value is obtained for each predefined current value of the supply current, which can then be evaluated in relation to the corresponding reference voltage value.To determine the current voltage readings, the methods described above for changing the predefined current values ​​of the supply current at the at least one active output channel A1, ..., A8 can also be applied under the respective predefined system state. Appropriate filtering methods or a waiting period can be applied to allow for transient responses and reduce noise. Storing the current or voltage values ​​currently measured at the at least one active output channel A1, ..., A8 of the power supply SV, as well as any voltage values ​​measured at the inactive output channels A1, ..., A8 of the power supply SV, can also be done, for example, in the control unit SE, which then performs an evaluation. Alternatively, the measured current and voltage values ​​can be forwarded to the evaluation and / or data processing unit and stored there.The evaluation is then also carried out, for example, by the evaluation and / or data processing unit.

[0063] In test step 104, the currently measured current values ​​for each predefined system state, determined at the respective predefined supply voltage values ​​at at least one switched-on output channel A1, ..., A8 of the power supply SV for the respective predefined system state, are compared with the corresponding reference values. The reference current values ​​determined in reference step 101 for the same system state and for the corresponding supply voltage values ​​are used for this comparison. When comparing the currently measured current values ​​with the corresponding reference values, it is checked whether a predefined tolerance range is exceeded at any of the predefined supply voltage values ​​at at least one active output channel A1, ..., A8 or in at least one active load circuit of the currently tested system state.If current voltage values ​​were measured in measurement step 103 instead of current values, these are compared in test step 104 with the corresponding reference voltage values ​​determined in reference step 101 and compliance with the specified tolerance range is checked.

[0064] The specified tolerance range can be expressed, for example, as a percentage or as an absolute value. A single tolerance range can be defined for all load circuits of the system or machine to be tested. However, it is also possible to define individual tolerance ranges for specific load circuits or to define tolerance ranges for load circuits that are identical or similarly configured. Furthermore, the tolerance range can be adjusted if, for example, during the course of the inventive method or after repeated application, it becomes apparent that the specified tolerance range has been chosen to be too narrow or too wide. A tolerance range that is too narrow can, for example, produce false errors due to fluctuations in load circuits and / or the aging of load units. This means that an error is displayed in a load circuit despite the system functioning correctly.If the tolerance range is set too broadly, actual wiring errors and / or functional faults of load units may be overlooked. The specified tolerance range can be adjusted, for example, based on current measurements recorded at various times in the load circuits.

[0065] If, during test step 104, it is determined that, under the currently tested, predefined system state, the tolerance range is not met at least for a predefined supply voltage value at the at least one switched-on output channel A1, ..., A8 of the power supply SV, when comparing the currently measured current value with the corresponding reference current value, then in display step 105 the load circuit connected to the at least one switched-on output channel is displayed. The display of the respective load circuit can be performed, for example, via the control unit SE. For this purpose, a display unit assigned to the control unit SE (e.g., a display, mobile display unit, etc.) can be used. The same applies if, instead of a current, a voltage is measured for the respective system state in the currently switched load circuit.

[0066] When test step 104 is performed on an evaluation and / or data processing unit, the display of the respective load circuit in which a wiring fault is suspected based on the measured current values ​​can, for example, be carried out via an output unit of the evaluation and / or data processing unit in display step 105. zB The measured current or voltage values ​​and / or the comparison with the reference current or voltage values ​​are graphically processed – for example, in the form of tables, curves, etc. During evaluation by an evaluation and / or data processing unit, previously stored current or voltage measurements of the load circuits can also be used. zB The current or voltage values ​​of the load circuits are graphically processed and displayed on an output unit in comparison to the currently measured current or voltage values.

[0067] If, in test step 104, no deviation (i.e., exceeding or falling below the specified tolerance range in terms of absolute or percentage) is detected for the currently tested, predefined system state by comparing the currently measured values ​​with the corresponding reference values, then the next predefined system state is checked. This next state is specified for the system or machine being tested and for which currently measured values ​​and reference values ​​are available. If, in one of the subsequent predefined system states, a deviation from the specified tolerance range, or the load-circuit-specific tolerance ranges, is detected by comparing the currently measured values ​​with the corresponding reference values, then the respective load circuits can also be displayed in display step 105.If, even under the other specified system conditions, no exceedances of the tolerance range or the load-circuit-specific tolerance ranges occur through the corresponding comparisons of currently measured values ​​with the corresponding reference values, the method according to the invention is terminated with a final step 106. In final step 106, it can be output, for example, that no anomalies could be detected in the tested load circuits of the system or machine.

[0068] Additionally, if these were measured in measurement step 103, the voltage values ​​currently measured at the output channels A1, ..., A8 of the power supply SV, which are switched off in the respective system state, can also be compared with corresponding reference voltage values ​​in test step 104. For example, if in test step 104 an output channel A1, ..., which is switched off for the specified system state to be tested, A8If a voltage value is detected that exceeds the reference voltage value (e.g., 0 volts) by more than the specified tolerance range, this may also indicate a fault in the wiring of the system or machine, or the associated control system. The corresponding load circuit can then be displayed again in display step 105.

[0069] Furthermore, current values ​​currently measured at the output channels A1, ..., A8 of the power supply SV, which are switched off in the respective system state, can also be considered in test step 104 in order to find wiring and / or functional errors in the system or the load circuits.

[0070] At the in Figure 1In the exemplary system or machine depicted, during a self-test phase, which includes at least measurement step 103, test step 104, display step 105, and completion step 106, the two exemplary wiring errors VF1 and VF2 would be detected under the corresponding predefined system states. For example, in test step 104, under a predefined system state in which at least the fifth output channel A5 of the power supply SV is switched on, it would be determined that a comparison of the currently measured current values ​​and, if applicable, the currently measured voltage values ​​with the corresponding reference values ​​lies outside the predefined tolerance range. The comparison leaves or exceeds the tolerance range, for example, in absolute value or as a percentage, because, for example, the motor M or...The fan unit is incorrectly not connected directly to ground via the fifth output channel A5, but due to the first wiring error VF1 (e.g., during the system or machine setup), it is connected to the sixth output channel A6. When the fifth output channel A5 of the power supply SV is activated, current is also fed into the load circuit connected to the sixth output channel A6. This means that in measurement step 103, for example, current values ​​at the fifth output channel A5 of the power supply that deviate from the corresponding reference current values ​​(e.g., are lower) are measured, which can cause the specified tolerance range for comparison with the corresponding reference values ​​to be exceeded, either in absolute value or as a percentage. Furthermore, voltage or current values ​​are measured at the sixth output channel A6 (which is switched off) in measurement step 103, values ​​which would not be measured with correct wiring at the sixth output channel A6.In test step 104, a fall outside the tolerance range(s) for this system condition can then be detected. (dh at least the fifth output channel A5 of the power supply SV is activated and the load circuit connected to the fifth output channel A5 of the power supply SV is displayed as faulty in display step 105.

[0071] Similarly, under appropriate system conditions - zB a system state in which, for example, only the seventh output channel A7 of the power supply SV is activated, and a system state in which zBIf only the eighth output channel A8 of the power supply SV is activated, the system or machine's self-test phase will detect a further, second wiring error VF2, in which the connection of the two sensor units DS and AS has been reversed. This wiring error, or the corresponding load circuits, can then also be displayed in display step 105.

[0072] Should the measured current values ​​in the system state with the seventh or eighth activated output channel A7 or A8 show such a small difference from the corresponding reference current values ​​that the comparison lies within the respective specified tolerance range(s), then the incorrect wiring of the second wiring fault VF2 will activate the wrong load unit or sensor unit DS or AS. This means that the function signal emitted by the acoustic sensor unit AS will be visible to the control unit SE as an input signal at the same time that the pressure sensor DS should actually be activated, and vice versa. Therefore, the second wiring fault VF2 can still be detected in test step 104 by means of an additional evaluation of the temporal assignment of input signals to the respective system states.It is therefore advantageous to select sensor units DS and AS that send a quiescent signal to the corresponding inputs I1 and I2 of the control unit SE as soon as a supply voltage is applied to the respective load circuit (e.g., 4 to 20 mA current loops, active high signal in quiescent state, etc.). This makes it very easy to determine, for example, whether the correct sensor unit, actuator unit, etc., is being supplied with power, or to detect any cable breaks in a load circuit.

[0073] Furthermore, it is noted that the inventive method can be used not only with switched-mode power supplies (SV), which convert an input AC voltage into a constant output DC voltage. The inventive method can also be applied, for example, to regulated voltage supplies for AC load units and thus to a wide range of consumers to verify the correct wiring and / or functionality of these load units.

Claims

1. Method for checking load circuits of a control system of an installation, wherein the control system, in addition to at least two load circuits, comprises at least one control unit (SE) and a clocked power supply (SV), by which the at least two load circuits, having in each case at least one load unit, are supplied with a supply voltage and / or a supply current via at least two output channels (A1 to A8), and wherein control signals are made available by the control unit (SE) to actuate the at least two output channels (A1 to A8), characterized in that the following steps are performed: - ascertaining reference current values at predefined voltage values of the supply voltage or reference voltage values at predefined current values of the supply current for respectively predefined installation states, wherein, in a predefined installation state, at least one output channel (A1 to A8) is activated and the respectively associated load circuit is supplied with the predefined voltage values by the supply voltage or with the predefined current values by the supply current (101); - storing the reference current values ascertained for the predefined installation states or the reference voltage values ascertained for the predefined installation states (102); - measuring present current values at the respectively predefined voltage values of the supply voltage or present voltage values at the respectively predefined current values of the supply current on the at least one activated output channel (A1 to A8) for the respectively predefined installation states during a self-testing phase (103); - checking (104) whether, in one of the predefined installation states, there is a departure from a predefined tolerance range, when comparing the respectively presently measured current values with the respectively corresponding stored reference current values, by at least one of the predefined voltage values of the supply voltage or whether, in one of the predefined installation states, there is a departure from a predefined tolerance range, when comparing the respectively presently measured voltage values with the respectively corresponding stored reference voltage values, by at least one of the predefined current values of the supply current; - and displaying the corresponding load circuit (105) when, in one of the predefined installation states, a departure from the predefined tolerance range by at least one of the predefined voltage values of the supply voltage or by at least one of the predefined current values of the supply current is identified.

2. Method according to Claim 1, characterized in that, for respectively predefined installation states, reference voltage values are furthermore ascertained and stored (101, 102) for at least any output channels (A1 to A8) that are deactivated in the respectively predefined installation state, that, during the self-testing phase, present voltage values for the output channels (A1 to A8) that are deactivated in the respectively present installation state are measured (103), that the measured voltage values are compared with the reference voltage values for the respective installation state (104), and that the respective load circuit in which there is a departure from a predefined tolerance range when comparing between measured voltage values and respectively corresponding stored reference voltage values is displayed (105).

3. Method according to either of Claims 1 and 2, characterized in that, for respectively predefined installation states, reference current values are furthermore ascertained and stored (101, 102) for at least any output channels (A1 to A8) that are deactivated in the respectively predefined installation state, that, during the self-testing phase, present current values for any output channels (A1 to A8) that are deactivated in the respective installation state are measured (103), that the measured current values are compared with the corresponding reference current values for the respective installation state (104), and that the respective load circuit in which there is a departure from a predefined tolerance range when comparing between measured current values and respectively corresponding stored reference current values is displayed (105).

4. Method according to one of Claims 1 to 3, characterized in that the reference current values and the reference voltage values for the respective installation states are ascertained (101) by way of a reference installation.

5. Method according to one of Claims 1 to 3, characterized in that the reference current values and the reference voltage values for the respective installation states are ascertained (101) during a commissioning phase of the installation to be checked or are derived (101) from current values and voltage values measured on the respective output channels during ongoing operation.

6. Method according to one of the preceding claims, characterized in that reference values of parameters and / or signals are acquired (101) at inputs (I1, I2) of the control unit (SE) and stored (102) for respectively predefined installation states, that present values of the parameters and / or signals are queried (103) at the inputs (I1, I2) of the control unit (SE) and compared (104) with the corresponding reference values during the self-testing phase for the respectively predefined installation states, and that the respective load circuit in which there is a departure from a predefined tolerance range when comparing between present values of the parameters and / or signals and the respectively corresponding stored reference values is displayed (105).

7. Method according to one of the preceding claims, characterized in that the predefined tolerance range is adapted for the comparison of the present current values with the corresponding reference current values and / or for the comparison of the present voltage values with the corresponding reference voltage values.

8. Method according to one of the preceding claims, characterized in that the respective installation states and thus the respectively activated and deactivated output channels (A1 to A8) and the voltage values for the supply voltage of the respective output channels (A1 to A8) or the current values for the supply current of the respective output channels (A1 to A8) are predefined by the control unit (SV).

9. Method according to one of the preceding claims, characterized in that provision is made for a predefinable waiting time (103) between changing the predefined voltage value of the supply voltage or the predefined current value of the supply current in the respectively predefined installation state and ascertaining the present current measured value for this predefined voltage value of the supply voltage.

10. Method according to one of Claims 1 to 9, characterized in that the predefined voltage values for the supply voltage are raised (103) in predefined voltage increments from a starting supply voltage up to a predefined rated voltage or up to an operating limit of the at least one load unit connected to the respective load circuit.

11. Method according to one of Claims 1 to 9, characterized in that the predefined voltage values for the supply voltage are raised (103) in the form of a linear voltage ramp with a predefinable gradient from a starting supply voltage up to a predefined rated voltage or up to an operating limit of the at least one load unit connected to the respective load circuit.

12. Method according to one of the preceding claims, characterized in that the ascertained reference current values and the ascertained reference voltage values are stored (102) in the control unit (SE).

13. Method according to one of the preceding claims, characterized in that the ascertained reference current values and the ascertained reference voltage values are transmitted to an evaluation and / or data processing unit and stored there (102).

14. Method according to Claim 13, characterized in that the predefined installation states are selected via the evaluation and / or data processing unit.

15. Method according to either of Claims 13 and 14, characterized in that the presently measured current values and / or voltage values are forwarded to an evaluation and / or data processing unit and stored there (103).