JP2002062933A - Field equipment - Google Patents

Abstract

(57) [Problem] To provide a field device having a diagnosis function for diagnosing not only the device itself but also another field device or a process. SOLUTION: A field device connected via a communication medium, a transmitting / receiving means for transmitting / receiving data or a signal, a numerical operation function, receiving information from another field device, and based on the received information, A diagnostic device for diagnosing the operating condition of a field device itself, another field device or a process loop.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a field device used in a process plant in which a series of processing departments and a control system are connected, and more specifically, to a higher-level system via a means such as digital communication. It concerns the connected field devices. In digital communication, for example, a communication protocol for the process industry, that is, a foundation field bus (Foundation Field Bus)
Fieldbus, PROFIB
US), Heart (HART), Brain (BRAIN)
Etc. can be used. The field device includes, for example, a sensor or an actuator device for a process industry, that is, a transmitter, a flow meter, a valve positioner, or the like.

[0002]

2. Description of the Related Art In an industrial control system in which an upper control system and a field device are connected via a communication medium, the functions of the field device are diversified. In addition, communication between field devices via a communication network represented by a field bus (Fieldbus) has become easier. With these, various possibilities are born.

In recent years, a field device has been provided with a computing function such as a CPU, thereby improving the inherent performance of the device and, at the same time, having a diagnostic function of the device itself, that is, a self-diagnosis function. Thereby, the maintenance information of the device can be notified to the control system connected online through digital communication.

For example, when the field device is a valve positioner, the control current of the electropneumatic conversion mechanism, which is a component of the device, is monitored, and when the steady-state value of the control current becomes more than or less than a certain value, the electropneumatic device is controlled. Issues an alert (alarm) or warning that the conversion mechanism needs maintenance. As a result, a self-diagnosis that prompts the user for maintenance is performed. With the self-diagnosis function, safer operation of the device can be realized, and maintenance that has been performed at regular intervals can be reduced to only when necessary, and maintenance costs can be reduced.

Conventional diagnostic functions include a function of monitoring internal data of a field device and diagnosing a device abnormality, and a function of issuing an alert or warning when an abnormality of a field device is confirmed. Further, as components, (1) a function of monitoring internal data, (2) storage means for storing abnormality diagnosis conditions, (3) abnormality diagnosis calculation means,
(4) Transmission means for transmitting a diagnosis result.

A conventional field device measures a process amount (pressure, flow rate, temperature, level, etc.) and sends the information to a higher-level device (control system) by communication. The host device is
Process control is performed by generating a control signal from the transmitted information and applying it to an operation terminal (positioner, electropneumatic converter, etc.). At this time, since the information of the process amount and the control signal is collected in the host device, the field device has only the signal output from each device or each input signal.

[0007] The host device stores information from each field device for a certain period of time in order to monitor the operation state of the process plant and the like, and has trend data of the operation state of the process plant. ing. This trend data is mainly used for monitoring the operation state of the process plant, but is also used for analysis when any trouble occurs.

FIG. 10 is a diagram showing the overall configuration of a typical process control system in which field devices and higher-level devices are connected via a field bus. In the figure, the configuration is simplified for simplification of the description.

As shown in FIG. 10, in a process control (automatic control) system, an interface device (I / O) 2, a sensor 3 and an actuator 4 are each connected to an upper bus via a field bus 5. The interface device (I / O) 2 is connected to the upper control system 1 via the upper bus 6. The upper control system 1 is configured by a computer or the like higher than the interface device 2.

Generally, in a real process control application, many devices are connected to one field bus segment. In addition, field bus segments, analog devices that do not go through the field bus,
Also, a plurality of I / O2s and the higher-level control system 1 are connected, respectively. In particular, the I / O 2 and the higher-level control system group 1 are provided with DCS (Distributed Co
control system).

The sensor 3 has an AI (Analog Inp).
ut: analog input). A process amount measured by the sensor element and peripheral hardware is input to the AI function block 7, and the AI function block 7 performs scaling, damping, and the like based on the input data. When there are a plurality of process quantities to be measured, such as a flow rate and a temperature, a plurality of (two in the figure) AI function blocks 7 can be arranged.

The actuator 4 includes a PID function block 8 and an AO (Analog Output).
t: analog output) function block 9. The PID function block 8 contains the AI
The control amount of the process control such as the flow rate and the temperature is controlled by the process amount transmitted from the function block 7 and the set point given from the upper control system 1. It does not need to be provided, and may be arranged in the sensor 3 or the I / O 2.

AO function block 9
Performs processing such as scaling on the operation amount given from the PID function block 8, and provides an output to the actuator element or its peripheral hardware. In addition,
FIG. 10 shows an example of a simple single loop control. However, it is also possible to combine a plurality of function blocks in more devices to form a complicated control system by a plurality of control loops and cascade control. is there.

In the configuration shown in FIG. 10, a diagnosis result such as a device alarm or a process alarm generated in each device or each function block is generated by each block and transmitted to the field bus 5 as necessary. Is done. Alternatively, the occurrence of an alarm can be recognized by reading the parameters related to the alarm of each block from the upper control system 1 side.

In general, a device alarm is to notify a device-specific problem, for example, a self-diagnosis result such as a failure of the sensor 3 or the actuator 4 or a memory abnormality.
It is generated by a function block, a resource block, or a block built into a device called a transducer block. A process alarm is generated when a process quantity, such as flow rate or temperature, such as an HI alarm or LO alarm, exceeds a certain set threshold.

[0016]

As described above, in the conventional field device, various merits have been brought about by providing a diagnostic function in addition to the original function of the device.
Since the diagnosis function is limited to the diagnosis of the field device itself, there is a limit to the diagnosis.

In addition, high-order equipment (such as DCS) used in a process plant is used to control the trend of important control loops.
Although data can be stored, countless field devices are used in the process plant, and it is difficult to store all the information of the field devices by the upper device. This is because if the amount of data increases, resources such as a memory for storing the data are required, and the resources are limited. In order to collect data, each of the field devices must be scanned for a certain period of time. Will be required.

Therefore, at present, in the process plant, the trend data as described above only monitors an important control loop.
However, once a trouble occurs, it is currently difficult to identify the cause of the trouble, and more data is needed to accurately analyze the trouble.

Further, if the diagnosis is based on the conventional concept as described above, the following items will be insufficient. An abnormal state that can be detected by comparing and diagnosing states between a plurality of field devices or between a plurality of function blocks cannot be generated as a diagnosis result (alarm). A diagnosis (alarm) cannot be generated based on more complicated conditions or application-specific conditions, rather than a simple determination that the process amount has exceeded a threshold value.

The present invention has been made in order to solve the above-mentioned problems of the prior art, and is not limited to the diagnosis of the device itself, and a diagnostic function for diagnosing other field devices or processes. An object of the present invention is to provide a field device provided with:

It is another object of the present invention to provide a field device for obtaining a control system capable of easily storing all information of each field device.

Further, the present invention enables the generation of a more sophisticated and complicated diagnosis result, which has been difficult in the past, and the generation of a diagnosis result according to a user application.
It is an object of the present invention to provide an environment in which a user can set diagnosis conditions by himself.

[0023]

The present invention employs the following structure to achieve the above object. (1) A field device connected via a communication medium, the transmitting / receiving means for transmitting / receiving data or a signal, receiving information from another field device, and based on the received information, the field device itself and other field devices. Diagnostic means for diagnosing the operating state of the field device or the process loop. (2) A field device connected via a communication medium, wherein a transmitting / receiving means for transmitting / receiving data or a signal and a signal which can be received, a signal which can be transmitted, and / or a signal having an internal time continuity are transmitted. Storage means for storing for a fixed period of time. (3) A field device connected via a communication medium, a transmitting / receiving means for transmitting / receiving data or a signal, receiving information from another field device, and based on the received information, the field device itself and another field device. Diagnostic means for diagnosing the operating state of the field device or the process loop; and storage means for storing a receivable signal, a transmittable signal, and / or a signal having internal time continuity for a predetermined time. A field device comprising: (4) The diagnostic means calculates a theoretical value of a controlled process amount based on internal data of the field device itself or data on a process value of another field device, and calculates the theoretical value as an actual process amount. The field device according to (1) or (3), wherein the diagnosis of the process loop is performed by comparing. (5) storage means for storing data on the normal or abnormal operation state of the field device used in the process loop, and internal data of the field device itself or data on process values of other field devices. And calculating the theoretical value of the process amount based on the data in the storage means, and comparing the theoretical value with the actual process amount to diagnose the process loop. ) Or (3). (6) The diagnostic means calculates a theoretical value of the process amount based on a valve opening signal corresponding to the valve opening of the control valve for controlling the flow rate, and compares the theoretical value with the actual process amount. The field device according to (4), wherein the process loop is diagnosed. (7) The diagnostic means calculates a theoretical value of the process amount based on a valve opening signal corresponding to the valve opening of the control valve for controlling the flow rate, and compares the theoretical value with the actual process amount. The field device according to (5), wherein the process loop is diagnosed. (8) The diagnostic means calculates a theoretical value of the flow rate in the control valve based on a valve opening signal corresponding to the valve opening degree of the control valve for controlling the flow rate, and calculates the theoretical value as an actual flow rate. The field device according to (6), wherein the diagnosis of the process loop is performed by comparing. (9) The diagnostic means calculates a theoretical value of the flow rate in the control valve based on a valve opening signal corresponding to the valve opening of the control valve for controlling the flow rate, and calculates the theoretical value as an actual flow rate. The field device according to (7), wherein the diagnosis of the process loop is performed by comparing. (10) The storage means is a FIFO (First In)
The field device according to (2) or (3), wherein the data is stored in a first out format. (11) The field device according to (2) or (3), wherein when storing the data or the signal, the storage unit has a function capable of presetting the data or the signal to be stored. (12) The field device according to (10), wherein, when storing the data or the signal in the FIFO format, the storage unit has a function capable of presetting the data or the signal to be stored. (13) When a storage stop command or a storage start command is received from outside the device, a function of interrupting or starting storage of each data or signal is provided.
(10) The field device according to any one of (12) to (12). (14) The diagnostic means can be programmed by a user according to an application, can be downloaded from outside the device, and can be partially changed by changing parameters after downloading. The field device according to (3). (15) The field device according to any one of (1) to (14), wherein the field device is a valve positioner.

According to the field device of the present invention, not only the diagnosis of the field device itself but also other field devices or processes can be diagnosed. Is detected and an alert or warning is issued, so that the process plant can be operated more safely and maintenance can be minimized, so that maintenance costs can be reduced.

In the field device of the present invention, all the information of the field device can be easily stored. As described above, by providing the process recorder function in the field device, when a trouble occurs, it is useful for analyzing the cause, and the load on the higher-level control system can be reduced.

With the field device of the present invention, a more sophisticated and complicated diagnosis result and a diagnosis result according to a user application can be generated, and further, an environment in which the user can set the diagnosis conditions by himself is obtained. be able to.

Here, the diagnostic conditions can be programmed by the user according to the application, can be downloaded from outside the device, and can be partially changed after the download by changing the parameters. can do. The diagnostic function block may further include a diagnostic function having a function of describing input / output conditions, diagnostic conditions, and parameter definitions of the diagnostic function block and performing download to an apparatus having the diagnostic function block. .

[0028]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram showing an embodiment of the present invention. FIG.
Is a process / process related to the first embodiment of the present invention.
It is a block diagram which shows a loop. Such a process loop is connected to each field device via means such as digital communication in an industrial control system.

As a specific diagnostic function, the most common control in the process control is to control the flow rate of the fluid flowing through the piping of the process plant. In order to adjust the flow rate, a valve generally called a control valve is inserted in a piping line, and the flow rate of the valve is adjusted by changing the valve opening. The fluid flowing through the pipes of the process plant has various properties, and a fluid having a high density may precipitate in the pipes and clog the pipes.

As shown in FIG. 1, a flow rate of a fluid in a pipe is generally controlled by using a controller 10 called a controller, and a flow meter 12 as a sensor for measuring the flow rate of the fluid in the pipe. , A feedback loop is formed with the valve positioner 14 for adjusting the valve opening of the control valve 14a. At this time, a failure of the flow meter 12 or the valve positioner 14
May cause loss of control in the worst case.

Conventionally, during operation of a process plant, periodic inspections of equipment and facilities used in the plant have been performed in order to prevent the above-mentioned problems. When conducting periodic inspections, a significant margin must be allowed for the inspection cycle. For this reason, periodic inspection schedules are set at sufficiently short intervals for the durability of equipment and facilities. As a result, the maintenance cost of the process plant has been high.

In recent years, it has become possible to use a communication protocol typified by a field bus for a field device used in a process plant, connect the field devices via a network, and perform bidirectional communication. As a result, the amount of information that can be acquired by the field device has been significantly increased, thereby enabling diagnosis of the field device itself, diagnosis of other field devices, or diagnosis of the process control loop itself.

The basic principle of the diagnostic function is that information is collected from a device sensing the process amount (flow rate, pressure, temperature, level, etc.) of the process loop and is compared with a theoretical process amount calculated in advance. This is to detect an abnormality in the process loop.

Specifically, the field device acquires data such as pressure, flow rate, valve opening, etc. around the pipe, calculates the flow rate of the fluid flowing through the pipe theoretically, and compares the theoretical value with the actual measured value. To diagnose the process. Or,
The field device stores in advance data on operating conditions (pressure value, flow rate value, valve opening value of the control valve, etc.) in a normal or abnormal state, and calculates the current process amount from the normal operating condition. (Eg, flow rate) is calculated and compared with the actual process amount to diagnose the process.

If the field device diagnoses the process control, detects an abnormality before causing the worst case that the control becomes uncontrollable, and issues an alert or a warning, the process plant can be operated more safely. At the same time, maintenance can be kept to a minimum, which has the advantage of reducing maintenance costs.

Including differential pressure transmitters, temperature transmitters, flow meters, valve positioners, etc. used in process plants,
A field device having a communication function and a data processing function has a function of receiving field information and diagnosing a device main body, a device other than the main body, or a process diagnosis.

In the first embodiment, a specific diagnosis method will be described, and the flow rate of the fluid is handled as the process amount. The elements that determine the flow rate, which is the process quantity, in normal flow rate control are shown below (see FIG. 2). - The pressure P _h and density [rho-expansion compensating coefficient epsilon-flow coefficient of the opening area S _v-fluid [Delta] P-regulating valve 14a the differential pressure between the pressure P _b of the downstream side of the upstream side of the regulating valve 14a α. When the control valve 14a considered orifice, the continuity equation of the formula and the flow of Bernoulli, volume flow Q _v flowing through the pipe can be expressed by the following equation (1). Q _v = εαS _v ｛2 / ρ (P _h −P _b )｝ ^1/2 …… (1)

Here, ε, α, and ρ are parameters determined by the properties of the fluid, and are considered to be constant. By stem 18 of the regulating valve 14a provided in the pipe 16 of the process plant is vertically moved, the opening area S _v of the regulating valve 14a is changed. Also, it is considered that P _h and P _b are parameters that change depending on the flow rate.

Here, if S _v , P _h , and P _b can be measured,
The flow rate flowing through the control valve 14a can be calculated. The flow meter 12 can be diagnosed by comparing the calculated flow rate with the sensing flow rate.

FIG. 3 is a flowchart showing a diagnosis method according to the first embodiment. First, step S1
In 1, a higher-level control system connected to a field device inputs a density representing a property of a fluid, a flow coefficient, and the like as basic data. As a result, the data of the fluid parameters, ρ, ε, and α, are stored in the field device.

[0041] Next, in step S12, the valve opening degree used for diagnosis, to collect data process variable (flow rate) Q _a like. In step S13, the process value from the valve opening degree of the regulating valve 14a (flow theoretical value) is calculated Q _p. In other words, the field device receives the valve opening signal of the control valve 14a and the upstream pressure P
_h, sense the downstream pressure P _b, from the sensing data, perform theoretical calculation of the flow rate Q _p flowing in regulating valve 14a. In addition, the field device outputs the output data Q _{a of the} flow meter.
To receive.

Further, in step S14, the theoretical value of the process amount (flow rate) is compared with the sensing value, and the deviation | that is the difference between the actual value of the controlled variable and the expected value corresponding to the set point is obtained. Q _a -Q _p | Request (minus target value from the control amount).

[0043] Then, in step S15, by comparing the Q _p and Q _a, when the deviation than a preset threshold value is large, further in step S16, opens the values of Q _p and Q _a, If it is determined that the operation will continue continuously for a preset time or more, an error or warning signal is transmitted in step S17.

That is, as a content of the diagnosis result, if the flow meter itself is equipped with a self-diagnosis function and there is no abnormality in the flow meter, the flow meter 12 provided in the process loop is used.
It is determined that there is a problem in the field device other than the above, the pipe 16, or the control valve 14a. If the state of the flow meter 12 is not known, it is determined that a system (process loop) including the flow meter is defective.

[0045] In such a diagnostic method, field devices, the upstream pressure P _h, must be equipped with sensors for sensing a downstream pressure P _b. This is not preferable because it not only complicates the instrumentation but also increases the cost of the field device. If the upstream and downstream pressure transmitters of the control valve 14a are provided,
A similar diagnosis can be made by receiving the output values of those transmitters.

Further, depending on the type of the process, the upstream pressure or the downstream pressure may be fixed. For example, when the downstream pressure is fixed to the atmospheric pressure, such as in a drain process, or when the tank whose level is controlled to be constant becomes the upstream pressure, the upstream pressure is considered to be constant. Alternatively, the drain of a tank whose level is controlled
In the process, both upstream pressure and downstream pressure are considered to be constant.
In such a case, a similar diagnosis can be made by storing information on the upstream pressure and the downstream pressure in the field device.

Conveniently, when data for theoretically calculating the flow rate cannot be collected, the field device stores in advance the operating conditions when the process loop (in this case, the flow control loop) is normal. . Regarding the data to be stored, the field device itself may collect the data of the operating conditions when the process loop is normal immediately after the operation is started, even if the operator inputs.

When controlling the process, the data of the process amount is always measured as the feedback amount, so that the data of the process amount can be obtained. For example, when the flow rate is controlled, a control loop as shown in FIG. 1 is formed. Here, when giving the process diagnostic function to the valve positioner 14, the valve positioner itself senses the signal of the valve opening degree of the control valve 14a, so by receiving the output data of the flow meter 12,
It is possible to acquire the valve opening signal of the control valve 14a and the data of the flow value.

The valve positioner stores data on the relationship between the control valve opening and the flow rate when the process is normal. For example, the flow rate data when the valve opening signal is 10% to 90% is 1
When stored at 0% intervals, the value of the flow value when the process is normal can be calculated by linear approximation from the valve opening signal during operation. The process can be diagnosed by comparing the calculated value with the value of the flow rate actually sensed by the flow meter. This method can be applied not only to the flow rate but also to any process amount such as pressure, temperature, and level.

Here, a specific calculation example will be described. This calculation example is data when the process loop stored in the valve positioner is normal. Valve opening signal 10% ......
Flow rate Q ₁₀ Valve opening signal 90% …… Flow rate Q ₉₀

The current valve opening is X%, the theoretical flow rate is Q _p ,
When the actual flow rate _{Q a, Q p = (Q} 10 -Q 90) /
(10% −90%) × (X−10%) + Q ₁₀ deviation = Q _a
Is -Q _p, deviation is normal if it is within the boundary value set in advance, the state beyond the boundary value, if continued a predetermined time set in advance, it is determined that the abnormal error Or issue a warning.

Here, a specific calculation example is shown. This calculation example is data when the process loop stored in the valve positioner is abnormal. Valve opening signal 10% ......
Flow rate Q ₁₀ Valve opening signal 90% …… Flow rate Q ₉₀

The current valve opening is X%, the theoretical flow rate is Q _p ,
When the actual flow rate _{Q a, Q p = (Q} 10 -Q 90) /
(10% −90%) × (X−10%) + Q ₁₀ deviation = Q _a
-Q is _p, deviation state in the inside the boundary value set in advance, if continued constant is preset time, transmits an error or warning is judged to be abnormal.

As described above, in the present embodiment, a communication protocol capable of transmitting and receiving data is set as a configuration condition,
When a data processing function, a data setting function for diagnosis, a diagnosis algorithm, and an alert generation function are provided, the operation in the diagnosis method includes (1)
Perform initial data input or data collection required for diagnosis, (2) collect data required for diagnosis, (3) perform process diagnosis based on the data collected in (2), (4) ( An alert is generated according to the diagnosis result of 3).

Next, a description will be given of a diagnostic method slightly different from the above-described diagnostic method in the present embodiment. FIG. 4 is a flowchart illustrating another example of a diagnosis method. In this flowchart, there is a difference in the processing in step S21.
And step S26 only. In the other steps, FIG.
The same processing as the processing in is performed. That is, step S
At 21, basic data, which is data relating to the process amount and the valve opening, is input or collected. Step S26
Then, it is determined whether or not continuous operation has continued for a predetermined time or more.

In this diagnostic method, (a) a communication protocol capable of transmitting and receiving data, (b) a data arithmetic processing function, (c) a data setting function used for diagnosis, and
When (d) self-collection function of basic data used for diagnosis, (e) diagnosis algorithm, and (f) alert generation function are provided, (I) initial data necessary for diagnosis is included in the operation of the diagnosis method. Input or collect data, (II) input or self-collect diagnostic basic data, (III) collect data required for diagnosis, and process based on the data collected in (IV) and (III). Diagnosis is performed, and an alert is generated in accordance with the results of the diagnosis of (V) and (IV).

In the present embodiment described above, the diagnosis function for one process loop is introduced, but diagnosis for more process loops can be performed. In the present embodiment, the flow rate flowing through the pipe 16 is treated as a process value, but the process value is not limited to such a flow rate,
Temperature, level, etc. vary. Each of these process quantities can be theoretically calculated according to the design values of the process plant equipment and the physical meaning of the process. Diagnosis is possible if the data necessary for the theoretical operation is obtained.

Further, even when data cannot be obtained conveniently, sensing a process amount (PV value) to be controlled when a process control loop is formed is indispensable for forming a feedback loop. Can be obtained. In addition, the operation amount (M
(V value) is a value output by the control device, so that this data can also be obtained without fail. Therefore, the field device can acquire at least two data in the process loop.

The field device stores the relationship between the above two data when the process loop is normal or abnormal, and compares it with the data during operation, so that any process loop can be diagnosed. is there. In addition, process plants are designed with a myriad of process loops combined to produce the final process product. Note that here, a single process
Although shown with respect to loop diagnosis, a process diagnosis combining a plurality of process loops is also possible in a similar manner.

As described above, in the first embodiment of the present invention, the field device connected to the higher-level control system via the predetermined communication medium uses the communication protocol capable of transmitting and receiving data, the process protocol, and the process plant. Numerical calculation function used in, and information of other field devices, based on the received information, the field device itself, another field device, or diagnostic means for diagnosing the operation state of the process loop It has. This field device
By diagnosing the process control, detecting the abnormality before the worst case that the control becomes impossible, and sending out the alert or the warning, the process plant can be operated more safely. At the same time, maintenance can be kept to the minimum necessary, which has the advantage of reducing maintenance costs.

Next, a second embodiment of the present invention will be described. FIG. 5 is a block diagram illustrating a configuration of the field device according to the present embodiment. This field device is provided with numerical calculation means such as a CPU, and also transmits and receives information between field devices as represented by a field bus.

As shown in FIG. 5, the process includes a differential pressure transmitter, a temperature transmitter, a flow meter, a valve positioner, and the like.
The field device used in the plant includes a communication unit (communication function) 20, a storage unit 22, and a function 24 inherent to the field device.

The communication means 20 comprises a receiving means for receiving a signal from outside the device and a transmitting means for transmitting a signal inside the device to the outside of the device. Also, the storage means 22
Information obtained by the communication means 20 or information generated by the function 24 inherent in the device, that is, a signal that can be received, a signal that can be transmitted, and / or a signal having internal time continuity is transmitted for a predetermined time. During this period, it is stored at a constant cycle. The field device handles a process amount, a control amount, and the like in the process plant as an output signal or an input signal.

As described above, the field device has a function of storing a signal processed by the device itself, a signal received by the field device, and the like for a certain period of time. Therefore, when a trouble occurs, the data stored in advance is read out, which can be used for the analysis of the trouble.

Since the storage capacity of the field device is limited, the data is stored in FIFO (First In Firsts).
t Out), the field device has a function of stopping data logging when a field device receives a fail signal or a data collection stop signal. Trend data for a certain period of time can be obtained. In other words, image-wise, a function that continuously records the cockpit state until the plane crashes, like a flight recorder on an aircraft, is applied to field devices to provide a process recorder function. It is.

In particular, in recent valve positioners, since the valve positioner has even the function of the controller, signals from a transmitter and the like are transmitted to the valve positioner by communication. As described above, the valve positioner tends to gather field information. Furthermore,
By storing the information sent by communication and the information generated by itself, the valve positioner is a device that can accurately grasp the state of the control loop and can maximize the process recorder function.

FIG. 6 is a flowchart showing the operation of the field device in this embodiment. First, in step S31, the field device stores (logs) the continuity information obtained by the communication by the communication unit 20 in the storage unit 22 for a certain period. In other words, after receiving the signal storage start command, it stores continuity information generated by itself for a certain period of time.

Then, information of another device (field device) having no process recorder function is read by communication, and the data is stored in the storage means 22 for a certain period of time (step S32). This memory is stored in FIFO (Fi
rst In First Out) to efficiently use limited resources.

Further, in step S33, when a fail signal or a data logging stop signal (signal storage stop command) is received, the operation of storing data in the storage means 22 is stopped. When a trouble occurs in the field device itself, a data logging stop signal is transmitted to the specified device (field device) (step S34).

Next, if a logging stop signal is not received in step S33, the flow advances to step S35 to continue collecting logging data by communication.
At 36, logging data is generated inside the field device. Subsequently, in step S37, data logging is performed, and the process returns to step S33.

As described above, in the field device according to the second embodiment of the present invention, the receiving means (communication means 20) for receiving a signal from the outside of the device and the transmission for transmitting the signal inside the device to the outside of the device. Means (communication means 20) and storage means for storing a receivable signal, a transmittable signal, and / or a signal having internal time continuity for a certain period of time at a certain cycle. I have. For this reason, all the information of the field device can be easily stored by the upper device, and the process recorder function provided in the field device helps to analyze the cause of trouble when it occurs. Can be reduced.

Next, a third embodiment of the present invention will be described. FIG. 7 is a diagram showing a configuration of a process control system using a field bus according to the present embodiment. The difference from FIG. 10 shown as a conventional example is that a diagnostic function block 7 is added.

That is, in the process control system, one I / O 2, one sensor 3 and one actuator 4 are connected to the upper bus via the field bus 5, and the interface device (I / O) 2 is connected to the upper bus. It is connected to the host-side control system 1 via the side bus 6. The upper control system 1 is configured by a computer or the like higher than the interface device 2.

Here, features of the diagnostic function block 30 according to the present embodiment will be enumerated. (i) Collect data of field devices such as the sensor 3 and the actuator 4 existing on the field bus 5.
The field device data is typically input / output data of a function block directly related to process control such as a process amount and an operation amount. Other data not directly involved in process control but useful for diagnosis,
For example, ambient temperature and humidity can be considered. These include
A temperature sensor signal for temperature correction of the flow sensor and the like are also included.

Data directly related to process control is as follows:
In many cases, the diagnostic function block originally exists inside the device, or has already been transmitted on a bus from a function block of another field device outside the device for the purpose of process control. In that case, the communication traffic on the field bus 5 does not increase due to the diagnostic function block.

(Ii) Input / output conditions, diagnostic conditions, and setting parameters are set according to the application. Input / output defines the format of a data group used for input / output. The diagnostic conditions include, for example,-comparison of collected data with a constant,-comparison of collected data with other data based on a predefined relational expression,-time-series continuous data of collected data (trend )
And a numerical value such as a comparison with a predefined change pattern, a numerical determination, and a logical determination in which these are combined and combined by AND, OR, and the like.

The setting parameter is a parameter that can be changed by digital communication after downloading the diagnostic function block, and is typically a constant for diagnosis, a coefficient of a relational expression, an operation mode setting (operation, non-operation, etc.). )and so on. The time-series data storage unit stores data specified at each set time interval in a memory (the storage unit 26 in FIG. 8).

Conceptually, as shown in FIG. 8, the diagnosis function block can be considered as a function in which the collected data is X _{1 to} X _n and the diagnosis result (alarm to be generated) is Y ₁ to Y _n. I can do it. The operation of the function can be partially changed by setting parameters externally.

(Iii) The setting of the condition is downloaded from the upper control system to the field device. FIG. 9 is a flowchart illustrating an example of the flow of a setting operation for the diagnostic function block.

As shown in FIG. 9, in step S41, the description of input / output conditions, diagnostic conditions, and parameter definitions is
Describe using a description expression or a programming language. The programming language may be a language specialized for the diagnostic function block, or may be a C language or a BASI.
A language based on a general high-level language such as the C language is also conceivable.

Next, in step S42, the described input / output conditions, diagnostic conditions, and parameter definitions are compiled into a format that can be understood by the diagnostic function block, and then downloaded to the diagnostic function block. Alternatively, if the device has the ability to understand, the text data is directly downloaded to the diagnostic function block without compiling. The simplest download method is to download the data from the upper control system 1 shown in FIG. 7 via the I / O 2 using the fieldbus communication online, but it is necessary to provide a separate communication line for each device offline. Connecting and downloading is also conceivable.

In developing input / output conditions, diagnostic conditions, and setting parameter definition descriptions, description using a text-based tool such as an editor can be considered. other,
GUI (Graphical Use) running on PC
If an application excellent in r Interface is prepared and conditions can be set by operating a mouse or the like, it becomes easier to use. In addition, a typical diagnosis form, for example, when a relational expression between the control valve opening and the flow rate is set in advance, and an abnormality is determined from the data of the control valve opening and the flow rate when the process is actually operating. Is easier to use if you prepare a template in advance and take care to minimize the input of conditions.

In step S43, after downloading is completed, data necessary for diagnosis is connected. This is the same as the normal connection setting of input / output data between function blocks. Specifically, a foundation field bus (Foundation Fieldbu)
s), the link object (L
Ink Object) and VCR (Virtual C)
communication Relations
setting of input and output on the application like p),
Make connection settings for communication.

(Iv) Diagnosis function block 7
Can exist on any device on the field bus 5. In the embodiment shown in FIG. 7, the diagnostic function block 7 is built in the actuator 4, but can exist in any device on the field bus 5. The data necessary for diagnosis can be collected via the field bus 5, so that other devices (field devices),
For example, it may be provided in the sensor 3 or in the I / O2. Similarly, it is also possible to provide a diagnosis result output of one diagnosis function block 7 as an input of another diagnosis function block 7.

(V) In step S44, the upper computer 1 manages the alarm. It is conceivable that the generated alarm is managed together with other general process alarms and device alarms by a system (typically called “device management system”) in the upper computer 1. This is performed not only with the time series management of the alarm of the device, but also with the parameter change and the repair history of the device. It is assumed that the management of change history of the diagnostic conditions and parameters of the diagnostic function block 7 is also performed by such a system.

In FIG. 7, the description has been made with the name of the diagnostic function block. The concept of function block is based on the Foundation Fieldbu
s is introduced in the field bus system represented by s and defines a set of functions as one block. What is important is that the mechanism for coupling inputs and outputs between function blocks is standardized.
Thus, an application (a control system in the process control field) can be configured by combining the function blocks with devices between different vendors connected on the field bus.

Therefore, if the following conditions are satisfied, the diagnosis function of the present proposal can be realized by the same concept without using a so-called function block. 1) One or more devices exist on a bus, and data of each device can be transmitted to each other. 2) Input / output formats (data types and data transfer methods) are standardized.

More specifically, the function of the present proposal can be realized in the same manner even when a digital signal is superimposed on an analog 4-20 mA signal which is a so-called hybrid, such as a HART protocol.

Further, by using a function block dedicated to diagnosis and performing diagnosis using data of a plurality of devices existing on the field bus, a more complex diagnosis which cannot be performed by a conventional function block. The generation of results is now possible. Therefore, a more advanced process diagnosis can be performed with a process control application.

Further, since the diagnosis conditions are programmed (customized) and downloaded to the diagnosis function block, the customization is high, and the diagnosis and alarm generation according to the user application can be performed. At the same time, parameters are defined so that the operation can be changed even after downloading, so that the system can be operated very flexibly. In addition, since an environment that allows the user to set the alarm conditions by himself can be provided, the user's unique know-how in operating the application is:
It will be available as is. In addition, the user can operate the diagnostic system by himself without depending on the system vendor.

As described above, according to the third embodiment of the present invention, the field device provided with the digital communication means includes the function block 7 for collecting internal data of the device itself or data from another field device, Other field devices or functions within other field devices
Input means for receiving data for diagnosis from the block 7; storage means 26 for storing data collected via the input means in time series; and one or more numerical and logical values stored in the storage means 26 Setting means for setting a diagnostic condition based on a combination of objective conditions, and generating means for generating one or more diagnostic results based on the set diagnostic condition. Therefore, it is possible to generate a more sophisticated and complicated diagnosis result and a diagnosis result according to a user application, and to obtain an environment in which a user can set a diagnosis condition by himself.

The diagnostic function block 7 may be provided with diagnostic means for executing the processing procedure of the flowchart of FIG. 3 or the flowchart of FIG.

Further, storage means for executing the processing procedure of the flowchart of FIG. 6 representing the storage method described above may be provided in the diagnosis function block 7.

Although the present invention has been described based on the preferred embodiment, the field device of the present invention is not limited to the configuration of the above-described embodiment, but may be modified from the configuration of the above-described embodiment. Field devices with various modifications and changes are also included in the scope of the present invention.

[0095]

As described above, according to the field device of the present invention, not only the diagnosis of the field device itself, but also the diagnosis of other field devices or processes can be performed, and the worst case in which the control becomes impossible. By detecting anomalies before issuing a situation and issuing an alert or warning,
In addition to being able to operate the process plant more safely,
Since maintenance can be minimized, maintenance costs can be reduced.

Further, in the field device of the present invention, all the information of the field device can be easily stored by the upper device, and the cause of the trouble can be analyzed by the process recorder function provided in the field device. And the load on the host-side control system can be reduced.

Further, according to the field device of the present invention,
It is possible to generate more advanced and complicated diagnostic results and diagnostic results according to the user application.
It is possible to obtain an environment in which the user can set the conditions for diagnosis.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a process loop according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing elements that determine a flow rate as a process amount.

FIG. 3 is a flowchart showing an operation in the first embodiment.

FIG. 4 is a flowchart showing another operation in the first embodiment.

FIG. 5 is a block diagram illustrating a configuration of a field device according to a second embodiment of the present invention.

FIG. 6 is a flowchart showing an operation in the second embodiment.

FIG. 7 is a diagram illustrating a configuration of a process control system using a field bus according to a third embodiment.

FIG. 8 is a diagram schematically showing collected data and a diagnosis result in the third embodiment.

FIG. 9 is a flowchart showing an operation in the third embodiment.

FIG. 10 is a diagram showing a configuration of a conventional process control system.

[Explanation of symbols]

 Reference Signs List 1 upper control system 2 I / O 3 sensor 4 actuator 5 field bus 6 upper bus 7 function block 10 controller 12 flow meter 14a control valve 14 valve positioner 16 piping 18 stem 20 communication means 22 storage means 24 field device originally Function 26 storage means 30 diagnostic function block

Claims (15)

[Claims] 1. A field device connected via a communication medium, comprising: a transmitting / receiving means for transmitting / receiving data or a signal; a field device itself receiving information from another field device and based on the received information; Diagnostic means for diagnosing the operating state of another field device or process loop. 2. A field device connected via a communication medium, comprising a transmitting / receiving means for transmitting / receiving data or a signal, a receivable signal, a transmittable signal, and / or internal time continuity. Storage means for storing a signal for a predetermined period of time. 3. A field device connected via a communication medium, comprising: transmitting / receiving means for transmitting / receiving data or a signal; receiving information from another field device; Diagnostic means for diagnosing the operating condition of another field device or process loop, and storage for storing a receivable signal, a transmittable signal and / or a signal with internal time continuity for a fixed time And field means. 4. The diagnostic means calculates a theoretical value of a controlled process amount based on internal data of the field device itself or data on a process value of another field device, and calculates the theoretical value of the actual process value. The field device according to claim 1, wherein the diagnosis of the process loop is performed by comparing the amount with a quantity. 5. A storage device for storing data of a normal or abnormal operation state of the field device used in the process loop, and internal data of the field device itself or process values of another field device. And calculating the theoretical value of the process amount based on the data relating to the data and the data in the storage unit, and comparing the theoretical value with the actual process amount to diagnose the process loop. The field device according to claim 1. 6. The diagnostic means calculates a theoretical value of a process amount based on a valve opening signal corresponding to a valve opening of a control valve for controlling a flow rate, and compares the theoretical value with an actual process amount. 5. The field device according to claim 4, wherein the diagnosis of the process loop is performed. 7. The diagnostic means calculates a theoretical value of a process amount based on a valve opening signal corresponding to a valve opening of a control valve for controlling a flow rate, and compares the theoretical value with an actual process amount. 6. The field device according to claim 5, wherein the diagnosis of the process loop is performed. 8. The diagnostic means calculates a theoretical value of the flow rate in the control valve based on a valve opening signal corresponding to the valve opening of the control valve for controlling the flow rate, and calculates the theoretical value of the actual value in the control valve. 7. The field device according to claim 6, wherein the diagnosis of the process loop is performed by comparing with a flow rate. 9. The diagnostic means calculates a theoretical value of the flow rate in the control valve based on a valve opening signal corresponding to the valve opening of the control valve for controlling the flow rate, and calculates the theoretical value of the actual value. 8. The field device according to claim 7, wherein the diagnosis of the process loop is performed by comparing with a flow rate. 10. The storage means includes a FIFO (First)
The field device according to claim 2, wherein data is stored in an “In First Out” format. 11. The data storage device according to claim 2, wherein said storage means has a function of presetting the data or signal to be stored when storing the data or signal.
The field device described in. 12. The storage means according to claim 1, wherein when storing data or signals in a FIFO format, the storage means has a function capable of presetting the data or signals to be stored.
0. The field device according to item 0. 13. The apparatus according to claim 2, further comprising a function of interrupting or starting storage of each data or signal when a storage stop command or a storage start command is received from outside the device. The field device described in. 14. The diagnostic means can be programmed by a user in accordance with an application, can be downloaded from outside the device, and can be partially changed by changing parameters after downloading. 4. The field device according to claim 3, wherein 15. A field device according to claim 1, wherein the field device is a valve positioner.