Method for checking automation field device during operation, and corresponding field device

Abstract

The invention relates to a method for online checking an automation field device (1), the field device (1) having a sensor unit (10) and a control / evaluation unit (11), and wherein the field device (1) determines or monitors at least one process variable of a medium on the basis of at least two sensor signals (Sn), the sensor signal (S1) is transmitted in a measurement channel (MK1) to a configurable pre-processing block (Preproc 1), the sensor signal (S2) is transmitted in a measurement channel (MK2) to a configurable pre-processing block (Preproc 2), the sensor signal (S1) and the sensor signal (S2) are successively connected in parallel to a verification channel (VK) having a configurable (verification) pre-processing block (Preproc V) for a predetermined period of time, the verification channel (VK) having a configurable (verification) pre-processing block (Preproc V), and the verification channel (VK) having a configurable (verification) pre-processing block (Preproc V). The pre-processing block (Preproc V) is configured in the same manner as the pre-processing block (Preproc 1) during a time period of a parallel connection of the digitized sensor signals (S1), and wherein the pre-processing block (Preproc V) is configured in the same manner as the pre-processing block (Preproc 2) during a time period of a parallel connection of the digitized sensor signals (S2), and wherein the pre-processing block (Preproc V) is configured in the same manner as the pre-processing block (Preproc 2) during a time period of a parallel connection of the digitized sensor signals (S1). The output signal (DATA V) of the pre-processing block (Preproc V) is synchronized in succession with the output signal (DATA 1) of the pre-processing block (Preproc 1) and the output signal (DATA 2) of the pre-processing block (Preproc 2) in a cycle-accurate manner, and is compared in a bit-true manner with respect to the output signal (DATA 1) of the pre-processing block (Preproc 1) and the output signal (DATA 2) of the pre-processing block (Preproc 2).

Description

Technical Field

[0001] The present invention relates to a method for online inspection of field devices in an automation technology. In the context of the present invention, online inspection of a field device means performing an inspection without interrupting the normal measurement or control operation of the field device. The acquisition of measurement or control data and the processing or preparation of measurement signals are not interrupted. Background Art

[0002] A variety of field devices have become known from the prior art and are widely used in industrial automation systems - both process automation and manufacturing automation. In the context of the present invention, a field device is considered to be all devices that are process-oriented and provide or process process-related information. Field devices record and / or influence - depending on the application area - at least one physical, chemical, or biological process variable of a process medium.

[0003] A measuring device includes at least one sensor unit - also referred to as a measuring sensor - and a transducer unit that is used to record the process variable of the medium. Each sensor unit provides analog measurement values that are typically digitally processed in one or more measurement channels of the transducer unit. In this context, reference is usually made to the preprocessing of the measurement values. The so-called raw measurement values can be obtained at the output of the measurement channel and are further processed by a computing unit to generate the actual process variable. For example, if the measuring device is used to measure pressure and temperature, conductivity, flow rate, pH value, or filling level, the measuring device provides information about the determined process variable: the pressure, temperature, conductivity, flow rate, pH value, or filling level of the medium in a container. The Endress + Hauser Group develops, produces, and distributes various such measuring devices.

[0004] Actuators, such as valves or pumps, are used to influence process variables, for example, to control or monitor the flow rate of a liquid in a pipeline or the filling level in a container.

[0005] Without restricting the focus of the method or the corresponding device according to the present invention, reference is made below to the prior art in the field of measuring devices, particularly flow devices. The flow measurement of a flowing medium is based on different measurement principles, and the choice of the final measuring device or measurement principle usually depends on the corresponding application.

[0006] Endress+Hauser offers flow meters based on five different measurement principles for determining the mass flow or volume flow of a determined medium. Coriolis flow meters are capable of determining the mass flow of a medium passing through a pipeline with high precision. Alternatively or additionally, they provide information about the density or viscosity of the flowing medium. Figure 1A variant of a Coriolis flowmeter is described in more detail - or more precisely - a variant of the sensor unit of a Coriolis flowmeter. For example, a flowmeter based on the ultrasonic transit time principle is described in international patent application WO 2014 / 001027 A1. For example, a flowmeter operating according to a thermal measurement method is shown in international patent application WO 2014139786 A1. Measuring devices based on the eddy current measurement principle and the magnetic induction measurement principle have also become well-known in the prior art in a variety of designs.

[0007] Depending on the location or the design of the automation system, the pipeline section for which the flow rate is to be determined can be a closed pipeline, a section of an open pipeline or a body of water. All flowable media can be used as process media.

[0008] Measuring devices are typically used in safety-critical applications, which require both the hardware and software components to operate correctly and without error. To meet this requirement, the functionality of the measuring device must undergo continuous monitoring with respect to both analog and digital signal processing. For example, diagnostic measures are taken to detect random hardware defects. It goes without saying that the measurement or control operation of field devices - especially in safety-critical applications - must not be interrupted during the inspection process. However, this continuous checking of the analog or digital signal path is not only necessary in safety-critical applications. On the contrary, users generally expect the installation base of field devices in their automation systems to work properly and to be able to detect and correct faults in a timely manner, especially during the development process. This is the only way to effectively prevent errors in field devices and any resulting downtime of the automation system.

[0009] DE 10 2005 025 354 A1 discloses a Coriolis flowmeter in which an analog measurement signal is superimposed on an auxiliary signal of known frequency and waveform for the purpose of functional checking. The auxiliary signal is then completely separated from the actual measurement signal in digital processing and used to check the plausibility of the correct functionality of the measurement channel. The known checking procedure is not designed for a high-precision (i.e., bit-true and / or cycle-exact) check of the digital part of the measurement channel.

[0010] In addition, it is already known that the preprocessing block of each measurement channel is designed redundantly - i.e., twice. This checking method requires doubling the digital circuitry, which also results in increased power consumption.

[0011] Another known inspection method involves feeding a test pattern via a multiplexer to the measurement channel to be inspected. This method can allow the correct functioning of the digital preprocessing block of the measurement channel to be inspected in a bit-true or cycle-accurate manner. The disadvantage of this method is that the signal path must be interrupted during the inspection process. As already mentioned, this is unacceptable in many use cases. For example, even a short interruption in a Coriolis flowmeter causes an interruption in the frequency and amplitude control and thus also an interruption in the provision of the measured value. Summary of the Invention

[0012] The object of the present invention is to provide a method for high-precision on-line inspection of at least one digital measurement channel of a field device in automation technology.

[0013] This object is achieved by a method for (on-line) inspecting a field device for determining and / or monitoring at least one process variable of a medium, wherein the field device has a sensor unit and a control / evaluation unit, the control / evaluation unit having a first measurement channel formed by a first preprocessing block, in particular configurable, a second measurement channel formed by a second preprocessing block, in particular configurable, and a verification channel formed by a configurable (verification) third preprocessing block, and in this method:

[0014] - The sensor unit generates a first sensor signal depending on at least one process variable, and the first sensor signal is sent to the first measurement channel.

[0015] - And at the same time, the sensor unit generates a second sensor signal depending on at least one process variable, and the second sensor signal is sent to the second measurement channel;

[0016] - Wherein the first sensor signal in the first measurement channel is converted into a first digitized sensor signal, and the first digitized sensor signal is sent to the first preprocessing block, and at the same time, the second sensor signal in the second measurement channel is converted into a second digitized sensor signal, and the second digitized sensor signal is converted and sent to the second preprocessing block;

[0017] - Wherein the first digitized sensor signal is sent to the verification channel within a predetermined (first) time period - for example, a time period during which the third preprocessing block is configured in the same way as the first preprocessing block - and is converted into a (digital) output signal of the third preprocessing block depending on the first digitized sensor signal, and the output signal is compared with the output signal of the first preprocessing block, for example, in a bit-true manner, for example, that is, synchronously in a cycle-accurate manner and in a bit-true manner;

[0018] - And wherein, the second digitized sensor signal is sent to the verification channel within a predetermined (second) time period - for example, the time period during which the preprocessing block and the second preprocessing block are configured identically - and is converted into a (digital) output signal of the third preprocessing block that depends on the second digitized sensor signal, and the output signal is compared with the output signal of the second preprocessing block, for example, in a bit-true manner or bit-by-bit manner, for example, that is, synchronized in a cycle-exact manner and compared in a bit-true manner.

[0019] Alternatively or additionally, this object is achieved by a method for online inspection of an automation technology field device, wherein the field device has a sensor unit and a control / evaluation unit, and wherein the field device determines or monitors at least one process variable of a medium based on at least two sensor signals,

[0020] wherein the first sensor signal is sent to a configurable first preprocessing block in a first measurement channel,

[0021] wherein the second sensor signal is sent to a configurable second preprocessing block in a second measurement channel,

[0022] wherein the first sensor signal and the second sensor signal are successively and in parallel connected to a verification channel having a configurable (verification) third preprocessing block within a predetermined time period,

[0023] wherein, during the time period of the parallel connection of the first digital sensor signal, the (verification) third preprocessing block is configured identically to the first preprocessing block,

[0024] wherein, during the time period of the parallel connection of the second digital sensor signal, the (verification) third preprocessing block is configured identically to the second preprocessing block, and

[0025] wherein the output signal of the (verification) third preprocessing block is successively synchronized with the output signals of the first preprocessing block and the second preprocessing block by a synchronization unit and compared in a bit-true manner. As mentioned before, the field device can also be an actuator.

[0026] In connection with the present invention, the term "online inspection of a field device" means that the inspection is performed during the regular measurement operation of the field device: the regular measurement operation is not interrupted or disturbed by the inspection process. Due to the cycle-exact synchronization of the output signals of the verification preprocessing block and the specific preprocessing block being inspected, the output signal of the verification channel can be inspected in a bit-true manner using each preprocessing block in x measurement channels (x > 1).

[0027] According to the development of the method of the present invention, there is provided that if the output signal of the first preprocessing block or the output signal of the second preprocessing block shows a deviation from the output signal of the (verification) third preprocessing block, an error message is generated. Preferably, the error message is issued only if the deviation occurs in at least two consecutive measurement cycles.

[0028] Furthermore, in combination with the method according to the present invention, there is provided an online check of at least two measurement channels, which is performed cyclically or non-cyclically.

[0029] According to the development of the method of the present invention, in order to perform a cycle-accurate synchronization of the output signal of the (verification) third preprocessing block with the output signal of the preprocessing block to be checked, the following method steps are performed:

[0030] - The preprocessing block of the measurement channel to be checked continuously provides an output signal at a defined time interval and signals the provision of the output signal by means of a ready pulse.

[0031] - After the verification preprocessing block is configured identically to the preprocessing block to be checked, the synchronization unit receives a command pulse from the control / evaluation unit at any time.

[0032] - After receiving the subsequent ready pulse of the preprocessing block to be checked, the synchronization unit sends a reset pulse (r) to the (verification) third preprocessing block after a defined waiting time ( ), where the waiting time ( ) is dimensioned such that the output signal of the (verification) third preprocessing block and the output signal of the preprocessing block to be checked are synchronized in a cycle-accurate manner.

[0033] It is considered advantageous in combination with the present invention if the following formula is used to determine the waiting time , then:

[0034] ,

[0035] where m specifies the time period known for the preprocessing block to be checked and - due to the same calibration - thus also for the (verification) third preprocessing block. m does not necessarily have to be > n, but will typically be > n. The number m indicates how many time units / cycles the processing block requires until the first valid result value is available after the reset. This is due to the stabilization time of the preprocessing block after the reset. In a typical / real-life scenario, m is 3*n + 7, i.e., 3 processing cycles including the stabilization time, plus a total of 7 time units / clock cycles overhead to complete the reset process and generate the ready pulse.

[0036] For example, a field device generates at least two analog sensor signals to determine or monitor a process variable of a medium, and these sensor signals are digitized and preprocessed in associated measurement channels. The field device can be, for example, a Coriolis flowmeter for determining the mass flow, density, and / or viscosity of a medium flowing through a pipeline. The mass flow can be continuously determined or monitored based on the phase difference occurring between a first sensor signal and a second sensor signal.

[0037] Furthermore, the invention also includes an automation technology field device, such as a Coriolis flowmeter, which is arranged to perform one of the methods according to the invention,

[0038] - wherein an A / D converter is provided in each of the first measurement channel and the second measurement channel, followed by a corresponding preprocessing block,

[0039] - wherein a switching element is provided via which the digital output signal of the A / D converter can be switched, for example successively, to the input of a (verification) third preprocessing block within a predetermined (first or second) time period,

[0040] wherein a synchronization unit is provided, which is configured to control the (verification) third preprocessing block such that the output signal of the (verification) third preprocessing block is synchronized with the output signal of the preprocessing block to be checked, in particular in a cycle-precise manner, and

[0041] - wherein the control / evaluation unit is configured to determine whether the preprocessing block under inspection is operating correctly by comparing the synchronized output signals of the preprocessing block to be checked and the (verification) third preprocessing block.

[0042] According to another embodiment of the invention, it is provided that the third preprocessing block is capable of being (re)configured. In further developing this embodiment of the invention, it is further provided that the third preprocessing block is configured in the same way as the first preprocessing block during a first time period - for example, exactly the same as the first preprocessing block - and, for example, differently from the second preprocessing block, and / or the third preprocessing block is configured in the same way as the second preprocessing block during a second time period - for example, exactly the same as the second preprocessing block - and, for example, differently from the first preprocessing block. Alternatively or additionally, for example, the first preprocessing block and / or the second preprocessing block can also be capable of being (re)configured.

[0043] According to another embodiment of the invention, the measurement channels have the same hardware. Additionally, the preprocessing blocks and the verification preprocessing blocks of the measurement channels can have the same hardware structure.

[0044] According to a development, the A / D converters in the first measurement channel and at least one additional measurement channel are Sigma-Delta converters.

[0045] The following embodiments of the field device according to the invention relate to a preprocessing block. They can be designed to provide, as an output signal, a low-pass filtered digital signal of an analog sensor signal of a measurement sensor. Alternatively, they provide, as an output signal, a digital signal corresponding to a statistical parameter (such as a minimum / maximum value or a standard deviation) of the analog sensor signal. According to a third variant, the preprocessing blocks are designed such that they provide, as an output signal, a digital signal representing the components of the analog sensor signal separated by frequency. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention will be described in more detail with reference to the following drawings. Among them:

[0047] Figure 1 : shows a longitudinal sectional view of a Coriolis flowmeter with a straight measuring tube known in the prior art,

[0048] Figure 2 : shows a block diagram of an embodiment of a component related to the present invention of a sensor unit of a measuring device having x measuring channels,

[0049] Figure 3 : shows a flowchart of an embodiment of a method according to the present invention, and

[0050] Figure 4 : shows a representation of a signal curve for the purpose of cycle-accurate synchronization of the output signals of a verification preprocessing block and a preprocessing block to be inspected. DETAILED DESCRIPTION OF THE INVENTION

[0051] Figure 1 A cross-section of a Coriolis flowmeter 1 is shown in a schematic representation. The Coriolis flowmeter 1 has a sensor unit or measurement sensor 10 and a control / evaluation unit or transducer unit 11. The housing having the control / evaluation unit 11 can be attached to the sensor unit 10 - as shown here - but it can also be arranged separately from the sensor unit 10. The sensor unit 10 is mounted in a pipe (not shown separately) via flanges 3a, 3b. The pipe and the aligned measuring tube 2 pass through a fluid medium F whose mass flow rate is to be determined. The flow direction of the fluid medium F is as indicated by the arrow.

[0052] In the illustrated case, the measuring tube 2 is designed as a straight measuring tube 2, which is fixed to the flange 3a and the flange 3b via end plates 4a, 4b on the inlet side and the outlet side, respectively. The flanges 3a, 3b and the end plates 4a, 4b are attached to the support tube 5 or are attached in the support tube 5. A variety of other designs of Coriolis flowmeters with at least one measuring tube are already known from the prior art. Examples of the sensors mentioned are those with a measuring tube with a cantilever mass, such as the sensors described in EP 97 81 0559, measuring sensors with a bent measuring tube (EP 96 10 9242), measuring sensors with two parallel straight or bent measuring tubes (US 4793191 or US 41 27 028) or measuring sensors with four bent measuring tubes.

[0053] In order to be able to use the Coriolis effect to determine the mass flow rate of the medium through the measuring tube 2, the measuring tube 2 is set into bending vibrations by a centrally arranged exciter 6. These bending vibrations occur in the plane of the figure. The vibration exciter 6 can be, for example, an electromagnetic drive consisting of a permanent magnet 7 and a coil 8. The coil 8 is fixed to the support tube 5, and the permanent magnet 7 is fixed to the measuring tube 2. The amplitude and frequency of the bending vibrations of the measuring tube 2 can be controlled via the current in the coil 8. The Coriolis force acting on the flowing medium in the plane of the figure causes a phase shift of the vibrations of the measuring tube, which depends on the mass flow rate and is measured by two vibration sensors 9a, 9b.

[0054] The two vibration sensors 9a, 9b are also arranged symmetrically to the vibration exciter 6 on the support tube 5. The vibration sensors 9a, 9b can be, for example, electromagnetic transducers, each consisting of a permanent magnet 12a, 12b and a coil 13a, 13b, and their arrangement can be similar to the permanent magnet coil arrangement of the vibration exciter 6: the two permanent magnets 12a, 12b are fixed to the measuring tube 2, and the two coils 13a, 13b are fixed to the support tube 5. The oscillatory movement of the measuring tube 2 generates an induced voltage in the corresponding coils 13a, 13b via the permanent magnets 12a, 12b. The signal output by the measuring sensor 10 is an analog sensor signal, and the analog sensor signal is fed to the measuring channel of the control / evaluation unit 11. Usually, at least one temperature sensor is provided, and at least one temperature sensor measures the temperature of the flowing medium F. The temperature sensor is not shown separately in the figure.

[0055] Figure 2 A block diagram of an embodiment of the transducer unit 11 of the field device 1 with x measuring channels MKx is shown, which is suitable for performing the method according to the invention. The method according to the invention is designed to perform an online check of the digital measuring channels MKx for their functionality - i.e., without interrupting the provision of the measured values MW.

[0056] From Figure 1In a measurement device 1 not shown and specified separately, x analog measurement signals Sx are tapped and preprocessed in x associated measurement channels MKx. The number of measurement channels MKx is equal to or greater than 2 (x ≥ 2). For example, Figure 1 the vibration sensors 9a, 9b of the Coriolis flowmeter 1 shown provide two analog measurement signals S1, S2. Usually, a temperature sensor (not shown separately) also provides an analog temperature measurement signal S3, which is fed into a third measurement channel MK3.

[0057] In each measurement channel MKx there is an AD converter, here a sigma-delta converter SDM, which generates a continuous digital data stream Bitstr x from the analog measurement signal Sx. The data stream Bitstr x is passed to a configurable preprocessing block Preproc x. At each output of the (separately) configurable preprocessing block Preproc x, the original measurement signal or output signal DATA x is available at equidistant time intervals and is passed to the microcontroller for further processing. The microcontroller is part of the control / evaluation unit 11 and continuously determines measurement values MW representing process variables of the medium F to be determined, based on the digital original measurement signals DATAx of the individual measurement channels MKx - usually at defined time intervals or at a cycle rate n.

[0058] According to the invention, in addition to the measurement channels MKx with x = 2, 3,... a verification channel VK with a configurable verification block Preproc V is provided.

[0059] According to a further embodiment of the invention, a synchronization unit SYNC and a delay unit Delay are assigned to the verification block Preproc V. With the aid of the verification block Preproc V, each of the x preprocessing blocks Preproc x in the measurement channels MKx (optionally configured separately or in a different way than at least one other preprocessing block Preproc) is checked at a predetermined or predeterminable time interval (i.e., during a predetermined first time period of the first measurement channel MK1 or during a predetermined first time period of the first measurement channel MK2) to see if it is working correctly. For the purpose of (online) checking, the data stream Bitstr x of the (currently) measurement channel Mkx to be verified is switched in parallel to the verification channel VK.

[0060] For example, the verification can be carried out as follows:

[0061] - The verification block Preproc V is configured in the same way as the preprocessing block Preproc x to be verified, for example identically to it;

[0062] - The data stream Bitstr x of the measurement channel MKx to be verified is connected in parallel with the input of the verification block Preproc V. - In Figure 2 this is the measurement channel MKx;

[0063] - Initialize and start the verification block Preproc V using a synchronization function;

[0064] - Check the equality or deviation of the output signals DATA x and DATA V of the measurement channel MKx to be verified and the verification channel VK, which are synchronized, for example, in a cycle - exact manner, where the deviation is evaluated as a fault of the pre - processing block Preproc x being examined.

[0065] Any detected faults can be signaled correspondingly via the microcontroller to the operator of the automation system.

[0066] The clock signal Clkx is used to operate the sigma - delta converter SDMx. With each cycle of the clock signal Clkx, the sigma - delta converter SDMx provides new data / bit bitstr x to the pre - processing block Preproc x. The Ready signal at the output of the processing block Preprocx appears only every "n" cycles of the corresponding clock signal Clkx. For the measurement channel MKx, the frequency of the clock signal Clkx and the factor "n" can be the same or different.

[0067] Figure 3 The flowchart shown describes the method steps performed according to another embodiment of the method of the present invention for (online) checking one of the measurement channels MKx, for example, the measurement channel MK2. Incidentally, it is preferably to check the individual MKx measurement channels cyclically.

[0068] After starting the program at point 20, a test is performed at point 21 to determine whether the predetermined time period or verification interval for checking the previously checked measurement channel MK - for example, MK1 - has expired. This test is performed successively until the verification interval for checking the previously checked measurement channel MK1 is completed. Once the verification interval of the previously checked measurement channel MK1 has ended, the verification channel VK or the verification block Preproc V is configured identically to the subsequently to - be - checked measurement channel MK2 at point 22. The data stream Bitstr2 of the to - be - checked measurement channel MK2 is connected in parallel with the verification channel VK; the output signal DATA 2 of the pre - processing block Preproc2 is synchronized with the output signal DATA V of the (verification) third pre - processing block Preproc V, and the verification channel MKV is started.

[0069] At point 24, the time point for waiting for the delivery result DATA V of the verification channel MK V. At point 25, the output signal DATA 2 of the measured channel MK2 that has been checked is compared bit - by - bit with the cycle - accurate output signal DATA V of the verification channel MK V. If the two output signals DATA 2 and DATA V are the same, the method steps of points 21 to 26 are successively repeated for the next measured channel MKx to be checked. If a deviation occurs during the check of one of the measured channels MKx, the method steps described in points 21 to 26 are repeated at least once. If the check reveals a deviation again, an error message is generated and displayed at point 28.

[0070] Figure 4 a to Figure 4 g show a representation of the signal curves for the purpose of cycle - accurate synchronization of the output signal DATA x of the currently to - be - checked pre - processing block Preproc x in the measured channel MKx and the output signal of the (verification) third pre - processing block PreprocV in the verification channel MKV.

[0071] At Figure 4 a and Figure 4 b, it can be seen that the pre - processing block Preproc x to be verified in the measured channel MKx continuously provides the output signal DATA x at a defined time interval n. The periodic provision of the output signal DATA x is signaled to the microcontroller by the ready pulse Rdy x ( Figure 4 c). Figure 2 Also shown is the ready pulse Rdy x that is sent to the control / evaluation unit 11 or the microcontroller .

[0072] After the verification pre - processing block Preproc V is configured identically to the pre - processing block Preproc x to be checked, the synchronization unit Sync receives (see ) the command pulse k from the control / evaluation unit at any subsequent time. Subsequently, the synchronization unit Sync waits for the next ready pulse Rdy x of the measured channel MKx. The corresponding waiting period or waiting time is marked with Figure 2 ( ) ( Figure 4 d).

[0073] The time period t is random and depends on when the control / evaluation unit or the microcontroller sends the command pulse k. For determinacy, the system waits for the next Rdy n pulse, and only from this point on can the calculation be made.

[0074] From the arrival of the next ready pulse Rdy x of the measurement channel MKx, the synchronization unit Sync waits for a further time unit . After the waiting time has elapsed, the synchronization unit Sync sends a reset pulse Reset V or r ( Figure 4 e, Figure 3 ) to the verification block Preproc V in the verification channel MK V. After the time unit m has elapsed, the verification channel MK V delivers its first synchronous output signal DATA V ( Figure 4 f) and the corresponding ready pulse ( Figure 4 g). From this point on, the output signal DATA V of the (verification) third preprocessing block Preproc V and the output signal DATA x of the preprocessing block Preproc x to be checked are synchronized in a cycle-exact manner. The control / evaluation unit 11 or the microcontroller now compares the output signal DATA V of the (verification) third preprocessing block Preproc V and the output signal DATA x of the preprocessing block Preproc x to be checked in a bit-true manner with respect to possible deviations.

[0075] List of reference signs

[0076] 1 Field device / measuring device / Coriolis flowmeter

[0077] 2 Measuring tube

[0078] 3 Flange

[0079] 4 End plate

[0080] 5 Support tube

[0081] 6 Oscillation exciter

[0082] 7 Permanent magnet

[0083] 8 Coil

[0084] 9 Vibration sensor

[0085] 10 Sensor unit / measuring sensor

[0086] 11 Transducer unit

[0087] 12 Permanent magnet

[0088] 13 Coil

[0089] 14 Switching element

[0090] MK Measuring channel

[0091] VK Verification channel

[0092] SDM Sigma-Delta Converter

[0093] Clk Clock

[0094] Bitstr Data Stream

[0095] Preproc Preprocessing Block

[0096] DATA Original Measurement Signal / Output Signal

[0097] Sn Analog Measurement Signal

[0098] Config Configuration Block

[0099] Rdy / r Ready Signal

[0100] Microcontroller

[0101] Delay Delay Signal

[0102] Start / s Start Signal

[0103] Sync Synchronization Signal

Claims

1. A method for (online) inspecting a field device (1) for determining and / or monitoring at least one process variable of a medium, wherein, The field device (1) has a sensor unit (10) and a control / evaluation unit (11). The control / evaluation unit has a first measurement channel (MK1) formed by a particularly configurable first preprocessing block (Preproc 1), a second measurement channel (MK2) formed by a particularly configurable second preprocessing block (Preproc 2), and a verification channel (VK) formed by a particularly configurable (verification) third preprocessing block (Preproc V). In the method: - The sensor unit (10) generates a first sensor signal (S1) depending on the at least one process variable, and the first sensor signal (S1) is sent to the first measurement channel (MK1), - And at the same time, the sensor unit (10) generates a second sensor signal (S2) depending on the at least one process variable, and the second sensor signal (S1) is sent to the second measurement channel (MK2); - Wherein, the first sensor signal (S1) in the first measurement channel (MK1) is converted into a first digitized sensor signal, and the first digitized sensor signal is sent to the first preprocessing block (Preproc 1). And at the same time, the second sensor signal (S2) in the second measurement channel (MK2) is converted into a second digitized sensor signal, and the second digitized sensor signal is converted and sent to the second preprocessing block (Preproc 2); - Wherein, the first digitized sensor signal is sent to the verification channel (VK) within a predetermined (first) time period - particularly the time period during which the third preprocessing block (Preproc V) is configured identically to the first preprocessing block (Preproc 1), and is converted into a (digital) output signal (DATA V) of the third preprocessing block (Preproc V) depending on the first digitized sensor signal, and the output signal (DATA V) is compared with the output signal (DATA 1) of the first preprocessing block (Preproc 1), particularly in a bitwise true manner, particularly specifically synchronized in a cycle - precise manner and compared in a bitwise true manner; - And wherein, the second digitized sensor signal is sent to the verification channel (VK) within a predetermined (second) time period - in particular, the time period during which the preprocessing block (Preproc V) is configured identically to the second preprocessing block (Preproc 2), and is converted into a (digital) output signal (DATA V) of the third preprocessing block (Preproc V) that depends on the second digitized sensor signal, and the output signal (DATA V) is compared with the output signal (DATA 2) of the second preprocessing block (Preproc 2), in particular in a bit - true manner or bit - by - bit, in particular synchronously with cycle - accuracy and in a bit - true manner.

2. The method according to claim 1, - wherein, if the output signal (DATA 1) of the first preprocessing block (Preproc 1) or the output signal (DATA 2) of the second preprocessing block (Preproc 2) shows a deviation from the output signal (DATA V) of the (verification) third preprocessing block (Preproc V), an error message is generated.

3. The method according to claim 1 or claim 2, Among them, The (online) inspection of at least two measurement channels (MKx) is performed cyclically or non - cyclically.

4. The method according to at least one of claims 1 to 3, Among them, To achieve cycle - accurate synchronization of the output signal (DATA V) of the (verification) third preprocessing block (Preproc V) with the output signal (DATA x) of the preprocessing block (Preproc x) to be inspected, the following method steps are performed: - The preprocessing block (Preproc x) of the measurement channel (MKx) to be inspected continuously provides an output signal (DATA x) at a defined time interval (n), and in each case signals the provision of the output signal (DATA x) with a ready pulse (Rdy x). - After the verification preprocessing block (Preproc V) is configured identically to the preprocessing block to be checked (Preproc x), the synchronization unit (Sync) receives a command pulse (k) from the computer ( ) at any later time. - After receiving the subsequent ready pulse (Rdy x) of the preprocessing block (Preproc x) to be checked, the synchronization unit (Sync) sends a reset pulse (r) to the (verification) third preprocessing block (Preproc V) after a defined waiting time ( ), where the waiting time ( ) is measured such that the output signal (DATA V) of the (verification) third preprocessing block (Preproc V) and the output signal (DATA x) of the preprocessing block (Preproc x) to be checked are synchronized in a cycle-exact manner.

5. The method according to claim 4, Among them, The waiting time ( ) is determined using the following formula: ， wherein, m indicates the time period known for the preprocessing block (Preproc x) to be inspected and the (verification) third preprocessing block (Preproc V) due to the same calibration.

6. The method according to at least one of the preceding claims, Among them, At least two analog sensor signals (Sn) are generated by the field device (1) to determine or monitor the process variable of the medium (F), and the sensor signals are digitized and preprocessed in associated measurement channels (MKx).

7. The method according to one or more of the preceding claims, Among them, The mass flow rate of the medium (F) flowing through the pipeline is continuously determined based on the phase difference between the first sensor signal (S1) and the second sensor signal (S2).

8. The method according to any one of the preceding claims, - wherein, the third preprocessing block (Preproc V) is capable of being (re)configured.

9. The method according to the previous claim, - wherein the third preprocessing block (Preproc V) is configured in the same way as the first preprocessing block (Preproc 1) during a first time period - in particular identically to the first preprocessing block - and in particular differently from the second preprocessing block (Preproc 2); and / or - Among them, the third preprocessing block (Preproc V) is configured in the same way as the second preprocessing block (Preproc 2) during a second time period - in particular identically to the second preprocessing block - and in particular differently from the first preprocessing block (Preproc 1).

10. The method according to any one of the preceding claims, - Among them, the first preprocessing block (Preproc 1) is reconfigurable; and / or - wherein the second preprocessing block (Preproc 2) is reconfigurable.

11. An automation technology field device, in particular a Coriolis flowmeter, configured to perform the method according to one of the preceding claims, - Among them, an A / D converter (SDM1; SDM2) is provided in each of the first measurement channel (MK1) and the second measurement channel (MK2), and the A / D converter is followed by a corresponding preprocessing block (Preproc1; Preproc2), - wherein a switching element (14) is provided, via which the digital output signal (Bitstr x) of the A / D converter (SDM1; SDM2) can be switched to the input of the (verification) third preprocessing block (Preproc V) during a predetermined (first or second) time period - in particular successively, wherein a synchronization unit (Sync) is provided, which is configured to control the (verification) third preprocessing block (Preproc V) such that the output signal (DATA V) of the (verification) third preprocessing block (Preproc V) and the output signal (DATA x) of the preprocessing block (Preproc1; Preproc2) to be checked are synchronized, in particular in a cycle-precise manner, - and wherein the control / evaluation unit (11) is configured to determine whether the preprocessing block (Preproc1; Preproc2) being checked is operating correctly by comparing the synchronized output signals (DATA V, DATA x) of the preprocessing block (Preproc1; Preproc2) to be checked and the (verification) third preprocessing block (Preproc x).

12. The field device according to the preceding claim, - the measurement channels (MKx) have the same hardware; and / or - wherein the control / evaluation unit ( , 11) is designed to configure the (verification) third preprocessing block (Preproc V) identically to the preprocessing block to be checked (Preproc1; Preproc2) within a predetermined (first or second) time period; and / or - the preprocessing block (Preproc x) of the measurement channel (MKx) and the verification preprocessing block (Preproc V) are identical in terms of hardware; and / or Among them, The A / D converters (SDM1, SDM2) of the first measurement channel (MK1) and the second measurement channel (MK2) are each sigma-delta converters.

13. The field device according to one of claims 11 to 12, Among them, The preprocessing blocks (Preproc x, Preproc V) are designed such that the preprocessing blocks provide a low-pass filtered digital signal of the analog sensor signal (Sx) as the output signal (DATA x, DATA V).

14. The field device according to one of claims 11 to 12, Among them, The preprocessing blocks (Preproc x, Preproc V) are designed such that the preprocessing blocks provide a digital signal as the output signal (DATA x, DATA V), the output signal corresponding to a statistical parameter of the analog sensor signal (Sx), such as a minimum / maximum value or a standard deviation.

15. The field device according to one of claims 11 to 12, Among them, The preprocessing blocks (Preproc x, Preproc V) are designed such that the preprocessing blocks provide a digital signal as the output signal (DATA x, DATA V), the output signal representing the components of the analog sensor signal (Sx) separated by frequency.

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