Monitoring the state of a vibronic sensor

Abstract

The present invention relates to: a method, in particular a computer-implemented method, for operating a device (1) for determining and / or monitoring at least one process variable of a medium; a computer programme for carrying out the method; and a computer programme product comprising a computer programme according to the invention. The device (1) comprises a sensor unit (2) and electronics (3) having at least one component (4) with a binary input and / or output, wherein at least a first and a second value for an input signal (E) and / or output signal (A) of the component correspond to a first and / or second state of the component (4). The method comprises the following method steps: - detecting a first (E1, A1) and / or second value (E2, A2) for the input signal and / or output signal (E, A) corresponding to the first and / or second state, - comparing the first (E1, A1) and / or second value (E2, A2) with a first (R1) and / or second predefinable reference value (R2) for the first and / or second state, and - on the basis of the comparison, detecting the presence of an electrically conductive substance (S) in the region of the component (4).

Description

[0001] Condition monitoring of a vibronic sensor

[0002] The invention relates to a method, in particular a computer-implemented method for operating a device for determining and / or monitoring at least one process variable of a medium, a computer program for executing the method according to the invention, and a computer program product on which a computer program according to the invention is stored. The medium is preferably located in a container, for example, in a tank or in a pipeline.

[0003] Field devices are used to monitor and / or determine at least one process variable, for example, a chemical or physical one, of a medium. For the purposes of this application, field devices essentially refer to all measuring devices that are used close to the process and that provide or process-relevant information, including remote I / Os, wireless adapters, and generally electronic components located at the field level. A large number of such field devices are manufactured and distributed by companies in the Endress + Hauser Group.

[0004] For example, the field device can be a level measuring device, flow measuring device, pressure and temperature measuring device, pH and / or pH-redox potential measuring device, or even a conductivity measuring device, which serves to record the respective process variables, such as level, flow, pressure, temperature, pH value, redox potential, or conductivity. The respective underlying measuring principles are well known from the state of the art and will not be listed individually here. Flow measuring devices are, in particular, Coriolis, ultrasonic, vortex, thermal and / or magnetic inductive flow measuring devices. Level measuring devices, in turn, are, in particular, microwave level measuring devices, ultrasonic level measuring devices, time domain reflectometric level measuring devices (TDR), radiometric level measuring devices, capacitive level measuring devices, conductive

[0005] Level gauges and / or vibronic level gauges are designed. Pressure gauges, on the other hand, are preferably so-called absolute, relative, or differential pressure devices, while a temperature gauge can, for example, use a thermocouple or a temperature-dependent resistor to determine the temperature.

[0006] A field device comprises at least one sensor unit that comes into contact with the process at least partially and at least temporarily, and electronics that serve, for example, to acquire, evaluate, and / or supply signals. The electronics can either be attached directly to the sensor unit or placed at a distance from the field device and connected to it. For numerous applications, especially safety-critical applications, it is necessary for the respective field device to operate as reliably as possible and to be able to withstand a wide range of environmental conditions, such as significant temperature and / or humidity fluctuations.

[0007] To ensure high reliability in such environmental conditions, the electronics are often encapsulated, for example, to prevent moisture ingress. However, with fully encapsulated electronics, the question of ease of use sometimes arises.

[0008] Accordingly, the object of the present invention is to provide a possibility with which a field device can operate reliably under a wide variety of environmental conditions and at the same time to ensure simple operation.

[0009] This object is achieved by a method, in particular a computer-implemented method, for operating a device for determining and / or monitoring at least one process variable of a medium, wherein the device comprises a sensor unit and electronics, wherein the electronics have at least one component with a binary input and / or output, and wherein an input and / or output signal of the component has / have a first or second state corresponding to a first or second predeterminable reference value for the input or output signal of the component. The method includes the following method steps:

[0010] - detecting a first and / or second value for the input and / or output signal corresponding to the first and / or second state, - comparing the first and / or second value with a first and / or second predeterminable reference value for the first and / or second state, and

[0011] - Detecting the presence of an electrically conductive substance in the area of ​​the component by comparison.

[0012] According to the invention, the input and / or output signal of the component is / are recorded, and the respective values ​​are compared with reference values ​​for the first and / or second state. Based on the comparison, for example, a deviation from the limit value beyond a predeterminable threshold, the presence of an electrically conductive substance in the area of ​​the component can be determined.

[0013] The method according to the invention serves to improve the functional safety and reliability of a field device in a simple manner. In particular, a field device designed to execute a method according to the invention can achieve a higher level of safety and / or higher availability. Structural measures on the respective field device are not necessary. Both a diagnosis and predictive maintenance can be performed.

[0014] For example, it is conceivable for the electronics component with the binary input and / or output to be freely accessible, while several, particularly all, other electronic components are encapsulated. In this case, it is advantageous to achieve high electronics reliability while simultaneously allowing simple and cost-effective operation of the electronics via the component with the binary input and / or output.

[0015] In one embodiment of the method, the first and / or second value for the input and / or output signal is / are recorded as a function of time. In this way, a temporal evaluation of the signal curve can be performed, and in particular, a temporal correlation and pattern recognition can be performed. This, in turn, allows for improved and expanded diagnostics. In a further embodiment, the component is a switching element that can be switched between a first and a second switching state. For example, it is a pushbutton switch, a normally closed contact, a normally open contact, or a changeover contact.

[0016] In this context, it is advantageous if the first and second values ​​for the input and / or output signal of the switching element correspond to the first and second switching states of the switching element. By comparing the values ​​for the input and / or output signal with the respective predeterminable reference values ​​according to the invention, for example, an unintended switching of the switching element can be detected.

[0017] In a further embodiment of the method, the component is a digital interface.

[0018] In this context, it is again advantageous if the first and second value of the input and / or output signal of the interface correspond to a first and second state of the interface.

[0019] Another embodiment of the method according to the invention involves the electrically conductive substance being a conductive liquid, for example, water, in particular penetrating moisture. The method can therefore detect the presence of moisture or condensation in the area of ​​the component.

[0020] It is advantageous if a notification is issued regarding the presence of the electrically conductive substance in the component area. In this regard, both diagnostics and predictive maintenance are conceivable.

[0021] In a preferred embodiment of the method, it is determined whether a difference between the first and / or second value for the input and / or output signal exceeds or falls below a predeterminable first threshold. Beyond a certain deviation from the predeterminable reference value, essentially a target value for the input and / or output signal, reliable functionality of the component can no longer be guaranteed. Such a comparison can lead to a more reliable assessment than a direct comparison of individual values.

[0022] A further embodiment includes the fact that a process which the component is designed to carry out is not executed as long as the electrically conductive substance is present in the area of ​​the component, i.e. as long as the value for the input and / or output signal exceeds or falls below the predeterminable limit value. A specific action or process is therefore not carried out as long as the substance, for example moisture, is present in the area of ​​the component, for example in the area of ​​the switching element or the interface. In this way, the unwanted execution of a specific process due to the presence of the substance can be avoided. In this respect, a switching element can be a switching process, for example, and an interface can be a signal transmission.

[0023] In this context, it is particularly advantageous if the process the component is used to perform is executed when the difference between the first and / or second value for the input and / or output signal does not exceed or fall below the predeterminable first limit value or a predeterminable second limit value. As soon as the predeterminable first limit value is exceeded or fallen below, the process is no longer executed. The process is only executed again when the first limit value or, for example, in the case of hysteresis, a predeterminable second limit value, is no longer exceeded or fallen below.

[0024] The object underlying the invention is further achieved by a computer program for determining at least one process variable of a medium with computer-readable program code elements which, when executed on a computer, cause the computer to carry out a method according to the invention.

[0025] The object underlying the invention is also achieved by a computer program product with a computer program according to the invention and at least one computer-readable medium on which at least the computer program is stored.

[0026] The method can in particular be implemented on a microcontroller.

[0027] The method is preferably used for a device for determining and / or monitoring at least one process variable of a medium, wherein the device comprises a sensor unit and electronics, which electronics are at least partially potted, encapsulated, or enclosed by a housing, in particular tightly, and wherein at least one component with a binary input and / or output, for example a switching element or a digital interface, is not potted, encapsulated, or enclosed by a housing, in particular tightly. In this context, it is advantageously possible to increase the security level of the field device using the method according to the invention without having to implement structural measures for this purpose. In this way, a cost-effective field device with a high security level can be realized.The method is also used to detect an electrically conductive substance in the area of ​​the component in the event that a housing of a corresponding device is not sealed, for example, because a cover has been removed or something similar. In this case, it is irrelevant whether the component in question is not potted, encapsulated, or enclosed by a housing, especially a sealed one.

[0028] The invention and its advantages are described in more detail with reference to the following figures, Fig. 1 to Fig. 4. It shows:

[0029] Fig. 1 is a schematic diagram of a field device with a sensor unit and electronics with a component having a binary input and / or output;

[0030] Fig.2 shows the time course of the input and / or output signal as a function of time for a component in the form of a switching element;

[0031] Fig. 3 is a schematic representation of a digital interface; and Fig. 4 shows the temporal progression of the input and / or output signal as a function of time for a component in the form of a digital interface.

[0032] Fig. 1 shows a field device 1 with a sensor unit 2 and an electronics 3, which has a component 4 with a binary input and / or output.

[0033] With the method according to the invention, it is possible to detect the presence of an electrically conductive substance S in the region of the component 4, for example condensation of the component 4. For example, it is conceivable that the component is a component of the electronics 3 that is accessible from the outside, while one or all of the other components of the electronics 3 can be potted, encapsulated, or surrounded by a housing.

[0034] The method according to the invention is based on a comparison of values ​​for the input E and / or output signal A with reference values ​​R corresponding to a first and second state Z. A first exemplary embodiment of the method according to the invention is illustrated below with reference to Fig. 2. In the case of Fig. 2, component 4 is a switching element which switches back and forth between a first switching state and a second switching state.

[0035] In Fig. 2a, the input signal E is shown as a function of time t. At time t0, a switching operation is triggered. At this time t0, the input signal E changes from a first value Ei to a second value E2. The output signal A is shown in Fig. 2b, also as a function of time t. The output signal A also changes at time t from a first value Ai to a second value A2. The first value corresponds to a first switching state and the second value to a second switching state. The detected value A2 for the output signal A corresponding to the second state of the switching element is, however, greater than a predefinable reference value Ri for the value of the output signal A. From this deviation or from the comparison with the reference value Ri, it can be concluded that a conductive substance S, in particular water, for example condensation, is present in the region of the switching element 4.The signal waveforms of the input E and output signal A are shown again in an enlarged view at time t0 in Fig. 2c.

[0036] Fig. 2 also shows an optionally usable reference value R2. As can be seen from Fig. 2b, the output signal A is not constant in the second switching state (t>t0) when the conductive substance S is present, but exhibits various jumps. An additional comparison with a second reference value R2 therefore also makes it possible to take hysteresis or similar factors into account when switching back to the first switching state, thus preventing unwanted switching in this respect as well.

[0037] Fig. 3 shows a schematic representation of a digital interface 5 with an external control element or a communication unit 6, an analog-to-digital converter 7 and a computing unit 8. Such an interface 5 can also be a component 4 with digital input and / or output in the sense of the present invention.

[0038] Similar to the case of Fig. 2, for a component 4 in the form of a digital interface 5 in Fig. 4, the input signal E and the output signal A are each shown as a function of time t. The input signal E periodically changes back and forth between a first state, which corresponds to a first value Ei for the input signal E, and a second state, which corresponds to a second value E2 for the input signal E (Fig. 4a). The same applies to the output signal A (Fig. 4b). However, in each case the predeterminable first reference value Ri is not exceeded, which is why it is concluded that no conductive substance S is present in the region of the interface 5.

[0039] Reference symbol

[0040] 1 field device

[0041] 2 Sensor unit 3 Electronics

[0042] 4 Component

[0043] 5 Digital interface

[0044] 6 External control element, communication unit

[0045] 7 Analog-to-digital converter 8 Computing unit

[0046] E Input signal A Output signal R Reference value S Substance

Claims

Claims: Method, in particular a computer-implemented method, for operating a device (1) for determining and / or monitoring at least one process variable of a medium, wherein the device (1) comprises a sensor unit (2) and electronics (3) with at least one component (4) having a binary input and / or output, and wherein at least one first and one second value for an input (E) and / or output signal (A) of the component corresponds to a first and / or second state of the component (4), comprising the following method steps: - Capturing a first (Ei , Ai) and / or second value (E2, A2) for the input and / or output signal (E, A) according to the first and / or second state, - Comparing the first (Ei, Ai) and / or second value (E2, A2) with a first (Ri) and / or second predefinable reference value (R2) for the first and / or second state, and - Detecting the presence of an electrically conductive substance (S) in the region of component (4) by comparison. Method according to claim 1, wherein the first (Ei, Ai) and / or second value (E2, A2) for the input and / or output signal (E, A) is / are detected as a function of time (t). Method according to claim 1 or 2, wherein component (4) is a switching element that can be switched between a first and a second switching state. Method according to claim 3, wherein the first (Ei, Ai) and second value (E2, A2) for the input and / or output signal (E, A) of the switching element correspond to the first and second switching states of the switching element. Method according to at least one of the preceding claims. wherein the component (4) is a digital interface (5). Method according to claim 4, wherein the first (Ei, Ai) and second value (E2, A2) for the input and / or output signal (E, A) of the interface (5) correspond to a first and second state of the interface (5). Method according to at least one of the preceding claims, wherein the electrically conductive substance (S) is a conductive liquid, in particular water, and in particular penetrating moisture. Method according to at least one of the preceding claims, wherein a message about the presence of the electrically conductive substance (S) in the area of ​​the component (4) is output. Method according to at least one of the preceding claims, wherein it is determined whether a difference between the first (Ei, Ai) and / or second value (E2, A2) for the input and / or output signal (E, A) exceeds or falls below a predefinable first limit value.A method according to at least one of the preceding claims, wherein a process for which the component (4) is used is not carried out as long as the electrically conductive substance (S) is present in the region of the component (4). A method according to claim 10, wherein the process for which the component (4) is used is carried out when the difference between the first (Ei, Ai) and / or second value (E2, A2) for the input and / or output signal (E, A) exceeds or falls below the predefinable first limit value or a predefinable second limit value. A computer program for determining at least one process parameter of a medium with computer-readable program code elements which, when executed on a computer, cause the computer to execute a method according to at least one of the preceding claims. A computer program product comprising a computer program according to claim 11 and at least one computer-readable medium on which at least the computer program is stored.

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