JP5293652B2 - Field equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide field equipment equipped with a device which can check only a computation function provided in each of a plurality of pieces of field equipment. <P>SOLUTION: This field equipment includes a computation checking device mounted in an inside of a casing of the field equipment, in the field equipment connected to a signal transmission line, and for outputting a signal of a physical quantity computation-processed based on a measured value in a process, to superordinate equipment via the signal transmission line. The computation checking device obtains input information of the computation processing and result information in the computation processing, compares result information recomputed with the input information, with the result information in the computation processing, or compares result information reverse-computed with the result information in the computation processing, with the input information, and verifies normal execution of the computation processing, based on an allowable threshold value. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a function expansion of a field device connected to a signal transmission line and outputting a signal obtained by calculating a physical quantity based on a process measurement value to a host device via the signal transmission line.

  FIG. 7 is an example of instrumentation of a process including a multivariable transmitter that is a field device. A plurality of transmitters 2, 3, and 4 are attached to the piping 1 of the process fluid F. Transmitter 2 (PT100) is a multivariable transmitter that measures the process flow rate from the pressure difference between the upstream and downstream of the throttle mechanism such as an orifice plate, and is calculated from the differential pressure, static pressure, temperature, and set parameters. The mass flow rate Qm is calculated, and a 4 to 20 mA analog signal or digital signal is transmitted to the control room host 6 via the signal transmission line 5. The host 6 executes process control and monitoring.

  The transmitter 3 (TT200) is a temperature transmitter having a plurality of inputs, for example, and transmits the measurement output signal to the host 6 via the transmission line 5. The transmitter 4 (FT100) is a flow rate measuring device such as a differential pressure transmitter, for example, and transmits the measurement output to the host 6 via the signal transmission line 5.

  The multivariable transmitter 2 is a small two-wire transmitter. For this reason, there are limitations on the memory size, communication speed, etc., and various parameters necessary for calculation are generated by the setting support tool 7 connected to the signal transmission line 5 and stored in the multivariable transmitter 2 in order to reduce the total number of data. to download. On the transmitter side, mass flow calculation is executed using these values and the differential pressure value, pressure value, and temperature value necessary for the flow calculation.

  Typical parameters of the multivariable transmitter 2 set and downloaded by the setting support tool 7 are Tag, range information, memo information, damping value, zero tone, and span tone data.

  In addition to the above parameters, the setting support tool 7 generates coefficient group data such as a gas expansion correction coefficient or coefficient information file and downloads it to the multivariable transmitter 2 via the signal transmission line 5. Regarding the multivariable transmitter and its setting support tool, Patent Document 1 discloses a detailed technique.

  FIG. 8 is a functional block diagram for explaining the cooperation between the multivariable transmitter 2 and the setting support tool 7. The multivariable transmitter 2 measures the differential pressure ΔP and the static pressure P by introducing the upstream pressure PH and the downstream pressure PL of the orifice 8 formed in the pipe 1, and the temperature of the resistance temperature detector, the thermocouple, etc. The measured value VT of the sensor 9 is input and the temperature T of the fluid F is measured.

  The setting support tool 7 is a PC equipped with a setting support tool that can be set and managed regardless of the manufacturer, such as FDT (Field Device Tool) and DTM (Device Type Manager). From this setting support tool 7, the user inputs parameter values such as expansion correction coefficient and temperature coefficient necessary for mass flow calculation, and digital data such as HART communication, Fieldbus communication, Profibus communication, etc. via the transmission line 5. The parameter is set by downloading to the multivariable transmitter 2 by communication.

The mass flow rate Qm in the multivariable transmitter 2 is calculated by the equation (1).
Qm = C / √ (1- β 4) · πd 2/4 · ε · √ (2ΔP / ρ) (1)

  Here, C is an outflow coefficient, β is a beta ratio (d (orifice inner diameter) / D (inner diameter of pipe)), ε is a gas expansion coefficient, ΔP is a differential pressure, and ρ is a fluid density. From the setting support tool 7, the outflow coefficient C, the beta ratio β, the gas expansion coefficient ε, and the like are downloaded as parameters.

The density ρ is a function of the static pressure P and the temperature T, and is calculated by equation (2).
ρ = K _ρ0 + K _ρ1 · f (T, P) + K _ρ2 · f (T ² , P ² ) (2)

The setting support tool 7 calculates the coefficients K _ρ0 , K _ρ1 , K _ρ2 from a plurality of sets of temperature, pressure, and density tables obtained by actual measurement by the least square method and downloads them to the multivariable transmitter 2. . The multivariable transmitter 2 calculates the density ρ from the equation (2) using this coefficient, and calculates the mass flow rate Qm from the equation (1).

  The calculation result of the mass flow rate and the measured values of the differential pressure, static pressure, and temperature in the multivariable transmitter 2 are transmitted to the host 6 through the signal transmission line 5 and uploaded to the setting difference support tool 7.

  FIG. 9 is a functional block diagram showing the internal configuration of the multivariable transmitter 2. The calculation means 21 having a CPU communicates with the host 6 and the setting support tool 7 via the signal transmission line 5 using the communication means 22 as an interface.

  The calculation means 21 communicates with data and program storage means 23 consisting of memory resources such as RAM and EEPROM, externally displays the setting and calculation results on the display means 24 such as an LCD, and the communication means 22 from the output means 25. Via the signal transmission lane 5.

  The differential pressure / static pressure detection means 26 inputs and measures the upstream pressure PH and downstream pressure PL of the orifice, converts them into digital signals, and passes them to the calculation means 21. Similarly, the temperature detection means 27 receives the detection value VT of the temperature sensor 9, converts it into a digital signal, and passes it to the calculation means 21.

  The calculation means 21 converts the process amount detected by the detection means 26 and 27 into a scaling value such as a% value specified by the user, for example, conversion or correction. It also controls and diagnoses peripheral devices.

  Thus, in the multivariable transmitter 2, since it is necessary to execute a complicated calculation process for calculating the mass flow rate, the calculation at each step of the calculation is normally executed in order to ensure the reliability. It has a check function to verify that.

  As a calculation check technique, Patent Document 2 discloses a technique for performing reverse calculation of a calculation result and comparing it with a value before calculation and verifying normal calculation by the deviation being within a predetermined threshold. FIG. 10 is a schematic diagram illustrating an example of a conventional calculation check method described in Patent Document 2.

  Simultaneously with the timing of normal computation, each point a (Scaling value: PWM output pre-value. PWM is a digital signal that is pulse-width modulated by a polynomial using a temperature-dependent dynamic correction coefficient), b (DP value : Value after scaling), c (X value: differential pressure value before correction), d (sensor value: sensor frequency value), a '(value that determines PWM value), b' (value before Scaling), c ' (DP value: corrected differential pressure value), d '(X value: square of sensor frequency) are latched at a time, from a' to a ", b 'to b", c' at separate timing The inverse operation of c ″, d ′ to d ″ is executed.

  Compare the difference between a, b, c, d, which are values before calculation, and a ″, b ″, c ″, d ″ calculated by inverse calculation, and whether the deviation is within a predetermined threshold. If it is determined whether there is an abnormality in the determination, alarm information is output.

JP 2009-031200 A JP 2005-309913 A

The prior art has the following problems.
(1) Due to recent improvements in memory size and higher functionality, for example, a flow rate calculation including recursive calculation from multiple inputs, as represented by a multivariable transmitter, or a differential pressure transmitter is installed. A diagnostic function such as the diagnostic function is installed, and the calculation of other field devices is similarly complicated.

  On the other hand, it is not easy to verify whether the calculation result is correct from the viewpoint of functional safety. For example, as shown in the example of FIG. 10, the reverse operation function for functional safety as installed in the multivariable transmitter needs to be incorporated in advance as a diagnostic application for each product. It was difficult to check only the arithmetic functions of multiple field devices.

(2) In addition, field device functions related to diagnosis represented by the clogging diagnosis function can be used by users and service personnel to calculate and set the operation of each device even though similar functions are installed in multiple field devices. It was necessary to check the functions one by one, and adjustment management of highly functional field devices was not easy.

  An object of the present invention is to realize a field device including a device capable of checking only a calculation function included in a plurality of field devices.

In order to achieve such a subject, the present invention has the following configuration.
(1) In a field device connected to a signal transmission line and outputting a signal obtained by calculating a physical quantity based on a process measurement value to a host device via the signal transmission line,
Computation check device mounted in the case of this field device,
This calculation check device
The input information of the arithmetic processing and the result information of the arithmetic processing are acquired, the result information obtained by recalculating the input information is compared with the result information of the arithmetic processing, or the result information of the arithmetic processing is inversely calculated. Comparing the result information with the input information, verifying normal execution of the arithmetic processing based on an allowable threshold, and sequentially obtaining arithmetic information in other field devices connected to the signal transmission line in sequence. Field equipment characterized by verifying normal execution of the operation processing .

( 2 ) When the calculation content of the field device to be calculated is not disclosed and provided with a simulation function, the calculation check device verifies the normal execution of the calculation process by the simulation function. The field device described in ( 1), which is characterized.

( 3 ) When the calculation content of the field device to be calculated is not disclosed and calculation check means is provided, the calculation check device performs normal execution of the calculation processing by the calculation check means. The field device according to (1) or (2), wherein the field device is verified.

( 4 ) The field device according to any one of (1) to ( 3) , wherein the calculation check device is mounted in a housing of a multivariable transmitter.

( 5 ) The field device according to any one of (1) to ( 4) , wherein the calculation check device is realized by a function block included in the field device.

According to the present invention, the following effects can be expected.
(1) By mounting a general-purpose operation check device in a specific field device, it becomes possible to verify the operation of other devices connected to the signal transmission line, improving the functional safety level of the system, Its use and management can be facilitated.

(2) The number of devices that can be checked within a predetermined cycle can be increased by enlarging the unchecking check.

It is a functional block diagram which shows one Example of the field apparatus to which this invention is applied. It is a functional block diagram which shows one Example of a calculation check device. It is a disassembled perspective view of the multivariable transmitter which shows the example of mounting of a calculation check device. It is a flowchart explaining operation | movement of a calculation check device. It is a sequence diagram in the case of performing the operation check of a some transmitter. It is a check cycle figure in the case of performing the arithmetic check of a some transmitter. It is an instrumentation example of a process including a multivariable transmitter that is a field device. It is a functional block diagram which shows the relationship between a multivariable transmitter and a setting support tool. It is a functional block diagram which shows the structural example of the conventional field device. It is a schematic diagram explaining the example of the conventional calculation check method of patent document 2. FIG.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing an embodiment of a field device to which the present invention is applied. The same elements as those of the conventional configuration described with reference to FIG.

  The feature of the present invention added to the conventional configuration shown in FIG. 9 is the configuration of the arithmetic check device 100 mounted in the multivariable transmitter 2. The calculation check device 100 communicates with the calculation means 21 to perform verification of its own calculation step, and calculates calculation information of other transmitters 2, 3, etc. connected to the signal transmission line 5 via the communication means 22. And verify the operation step.

  FIG. 2 is a functional block diagram showing an embodiment of the operation check device 100. As shown in FIG. The calculation check device 100 includes an information acquisition unit 101, a confirmation calculation unit 102, a result determination unit 103, and a storage unit 104. Further, as an option, a confirmation calculation means 105, a calculation rewrite means 106 and a storage means 107 associated therewith are provided.

  The information acquisition unit 101 is a part for acquiring calculation information of the target device, and includes a first calculation information acquisition unit 101A and a second calculation information acquisition unit 101B. The first calculation information acquisition unit 101A acquires information before calculation of the target device (calculation result information in the case of reverse calculation) A and passes it to the confirmation calculation unit 102.

  The second calculation information acquisition unit 10 </ b> B acquires calculation result information (information before calculation in the case of reverse calculation) B and passes it to the result determination unit 103. The calculation result of the confirmation calculation means 102 is passed to the result determination means 103. The calculation in the confirmation calculation unit 102 and the result determination unit 103 is executed by the function of the calculation unit 21 including a CPU.

  The confirmation calculation means 102 acquires the value A to be calculated, and executes recalculation or reverse calculation based on a pre-installed calculation algorithm or a calculation algorithm uploaded from the target device for each diagnosis method, Calculation result information C is output.

  The result determination means 103 compares the recalculation or reverse calculation calculation result information C from the confirmation calculation means 102 with the input B of the second calculation information acquisition means 10B. If the difference between the two is within a predetermined threshold, the output of normal is fed back to the device to be diagnosed.

  The storage unit 104 stores information such as the calculation result of the confirmation calculation unit 102, the determination result of the result determination unit 103, and the history.

  The confirmation calculation means 105 is mounted when a program for confirmation calculation is provided as an option, and a specific calculation step is executed by the algorithm of the confirmation calculation means 105.

  The calculation rewriting means 106 is an option when the device to be checked for calculation does not disclose the calculation and cannot be checked with a simulation function or the like. In this case, the manufacturer's service rewrites the calculation contents of the confirmation calculation means 105 by the calculation rewrite means 106 in advance. The storage unit 107 stores the calculation result information of the confirmation calculation unit 105.

The threshold value used for the determination of the result determination unit 103 can use various forms listed below by a known technique.
(A) For example, in order to calculate an allowable deviation between the calculation result value of the acquired target device and the check calculation result by the calculation check device, a region determination by a linear expression, a polynomial for correction calculation, an average calculation, A method that uses numerical analysis methods based on various functions and their combinations.

(B) A region having a certain boundary is determined from a sampling collection and distribution analysis of many points by a statistical method, for example, a method using simultaneous equations and determinants for approximation, or a method such as broken line approximation. A method of determining whether or not the area is within the threshold as an allowable threshold.

(C) A method for determining a threshold value for comparison determination using other numerical analysis or an approximate method. For example, by extracting frequency components such as Fourier transform and wavelet transform, and calculating the approximate region obtained by combining them, the threshold value that can be allowed by the difference between the result of the confirmation operation and the operation result value of the target device is set. A method to set and determine whether it is within a threshold.

(D) Set a threshold that is allowed by the difference between the result of the confirmation calculation and the calculation result value of the target device, including a part of the calculation performed in the device and its reverse operation, and whether the value is within the threshold A technique to help with judgment.

(E) A method for making use of the difference between the confirmation calculation result based on the calculation by the user setting and the calculation result value of the target device for the determination. As a support tool at the time of user setting, for example, a tool such as PCTool is included.

  FIG. 3 is an exploded perspective view of a multivariable transmitter showing an implementation example of the operation check device 100. The arithmetic check device 100 can be mounted in the form of a module in the space inside the device housing 2A.

  2B is a cover, and 2C is a CPU assembly. When the internal space is limited as in the case of an explosion-proof device, mounting in the explosion-proof region is possible without special design of the housing by replacing the assembly of the display unit with the operation check device 100 and mounting.

  FIG. 4 is a flowchart for explaining the operation of the arithmetic check device 100. Step S1 is a diagnostic method determination step, which is a branch for selecting a diagnostic method. When checking only the threshold value, the process branches to S1, when the calculation is simple, the process branches to S3 or S4, and when the calculation is not disclosed, the process branches to step S5.

  This is because the diagnostic function of the selection function in the diagnostic method determination step differs depending on the device. On the other hand, if the calculation is completely undisclosed and monitoring by using the simulation function is not possible, check the calculation using the check calculation means downloaded in advance by the manufacturer's service at this step. Select.

  In this way, the diagnosis method determination step is to determine the device and its determination method. The model determination function, the determination method and determination location by the user can be specified, and the execution method is determined depending on the type of items to be diagnosed. You can choose.

  In step S2, diagnosis is performed in time series, only a threshold value is checked by a statistical method, and an alarm is transmitted when an abnormality occurs. A value set by the user in advance or an abnormal value is monitored and checked.

  In step S3, when the calculation formula is simple, for example, when the calculation check device 100 can acquire the instantaneous flow rate value Ft, the integrated time t and the integrated flow rate value FTt are calculated to check the integrated flow rate value of the target device. do.

  In step S4, when the calculation formula is simple, a part of the calculation such as inverse calculation is disclosed, and a relational expression between parameters is given manually or the like.

  If the calculation of the target device is not disclosed and the process branches to step S5, the presence / absence of the simulation function is confirmed in step S6, and the branch is selected in step S7 or step S8.

  In step S7, the check calculation means 102 does not perform calculation, but transmits a simulation value using the simulation function of the target device, and confirms that the calculation returns correctly.

  This simulation function currently inputs simulated values to the device only when the user installs it and checks the calculation results of the device. Make sure that operation is not impaired.

  In step S8, if the device to be checked for calculation does not disclose the calculation contents and cannot be confirmed by the simulation function or the like, the calculation check device 100 sets the value before calculation and the value after calculation of the target device. For example, and collates with the result of the algorithm downloaded in advance by the service of the manufacturer. If the value before calculation of the target device cannot be acquired, nothing is executed.

  FIG. 5 is a sequence diagram in the case where the operation check of a plurality of transmitters is executed. FIG. 5A shows a cycle T1 required for one check operation of the multivariable transmitter 2 (PT100), and check operations PT1, PT2, and PT3 can be set.

  FIG. 5B shows a cycle T2 required for one check operation of the temperature transmitter 3 (TT200), and check operations TT1, TT2, TT3, and TT4 can be set. FIG. 5C shows a cycle T3 required for one check calculation of the flow rate transmitter 4 (FT100), and the check calculations FT1 and FT2 can be set.

  When there is no scheduling function, such as a fieldbus system, it is not always necessary to execute all of the check operations, and it is possible to perform it without fail at a possible timing.

  For example, as shown by the dotted arrow in FIG. 5, after the PT1 check calculation is determined at the PT100 check timing, the TT4 check calculation is determined at the TT200 check timing. Checks are performed uniformly using the counter assigned to the check operation.

  FIG. 6 is a check cycle diagram in the case where an operation check of a plurality of transmitters is executed. FIG. 6A is a timing chart of communication taking the time axis in the X direction. The calculation check of PT100, TT200, and FT100 is sequentially executed in sequence for a predetermined time during the idle time of information update processing by communication between PT100, TT200, and FT100 executed at a predetermined cycle. In addition, the calculation check function can be operated using the scheduling timing on the fieldbus communication.

  Within this check time, a confirmation calculation is performed and a result is determined by recalculation or reverse calculation of the calculation check device. FIG. 6B is a flowchart showing the same processing as that in FIG. If there is an abnormality as a result of the calculation check, an alarm is generated.

  As an interface for the user with respect to the operation check device 100 mounted in the multivariable transmitter 2, when the setting support tool 7 is connected to the signal transmission line 5, it is practical to use the operation screen. This interface can also be operated and monitored from the PC connected to the host 6 or the signal transmission line 5.

DESCRIPTION OF SYMBOLS 1 Piping 2 Multi-variable transmitter 3 Temperature transmitter 4 Flow transmitter 5 Signal transmission line 6 Host 7 Setting support tool 8 Orifice 9 Temperature sensor 21 Calculation means 22 Communication means 23 Storage means 24 Display means 25 Output means 26 Differential pressure / static Pressure detection means 27 Temperature detection means 100 Calculation check device

Claims (5)

In a field device connected to a signal transmission line and outputting a signal obtained by calculating a physical quantity based on a process measurement value to a host device via the signal transmission line,
Computation check device mounted in the case of this field device,
This calculation check device
The input information of the arithmetic processing and the result information of the arithmetic processing are acquired, the result information obtained by recalculating the input information is compared with the result information of the arithmetic processing, or the result information of the arithmetic processing is inversely calculated. Comparing the result information with the input information, verifying normal execution of the arithmetic processing based on an allowable threshold, and sequentially obtaining arithmetic information in other field devices connected to the signal transmission line in sequence. Field equipment characterized by verifying normal execution of the operation processing . The calculation check device verifies the normal execution of the calculation processing by the simulation function when the calculation contents of the field device to be calculated are not disclosed and provided with a simulation function. The field device according to claim 1 . The calculation check device verifies the normal execution of the calculation process by the calculation check means when the calculation contents of the field device to be calculated are not disclosed and calculation check means is provided. The field device according to claim 1 , wherein the field device is characterized. The operation check device, field device according to any one of claims 1 to 3, characterized in that it is mounted in a housing of multivariable transmitter. The operation check device, field device according to any one of claims 1 to 4, characterized in that it is realized by function blocks field device is provided.