JP2008146362A - Field equipment system and diagnostic method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a field equipment system and its method for improving reliability of the communication of a field equipment system by predicting occurrence of such abnormality as the opening and short-circuit of a transmission line in advance, and preventing occurrence of any communication failure as regards the abnormality diagnosis of the field equipment system. <P>SOLUTION: In this field equipment system equipped with a diagnostic module for detecting abnormality of a transmission line, the diagnostic module is provided with at least one measurement part or the like for measuring the electric characteristics of the transmission line. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an abnormality diagnosis for a field device system, and more particularly to a field device system and method for improving reliability of communication of a field device system with respect to an abnormality such as an open / short circuit of a transmission line.

  For example, in plant instrumentation, a system in which a host device and a field device are connected by a transmission line and communication is performed between the devices and devices may be used. In such a system, the transmission line is opened or short-circuited due to carelessness and a communication failure occurs, and the host device cannot obtain the measured values of the field device, thereby reducing the reliability of the system. It may happen.

  FIG. 10 shows a configuration of a conventional general field device system. The field equipment system communication standards include Foundation Fieldbus (FOUNDATION FIELDBUS), Profibus (PROFIBUS), Heart (HART), and the like.

  A common DC power source 3 is connected to the transmission lines 1 and 2, and a pair of terminators 4 and 5 are connected to both ends of the transmission lines 1 and 2, and a host device 6 that performs communication via this transmission line is connected.

  Further, linking devices 44 and 49 are connected to the transmission line branched from the transmission lines 1 and 2, and the linking device 44 is connected to the linking device 44 via the transmission line, such as a differential pressure transmitter 45, a temperature transmitter 46, A vortex flowmeter 47 is connected. Similarly, a differential pressure transmitter 50, a temperature transmitter 51, and a vortex flowmeter 52 are connected to the linking device 49 via a transmission line. Other field devices include electromagnetic flow meters, Coriolis mass flow meters, ultrasonic flow meters, and level meters.

  A similar field device system is described in FIG. 1 of Patent Document 1, and its operation will be described (see Patent Document 1).

  The transmission line may be inadvertently cut and opened, or the insulation may deteriorate due to the influence of the surrounding environment, resulting in a short circuit.

  When such a transmission line abnormality occurs, a communication failure may occur. However, Patent Document 1 detects and diagnoses an abnormality such as an open or short circuit of the transmission line that is the cause of the communication failure, and determines the type of abnormality. A wiring failure detection unit and a wiring failure diagnosis manager (not shown) for reporting to the user are provided.

  The wiring defect detection unit includes an ohm meter, a voltmeter, a noise meter, etc. (see FIG. 3 of Patent Document 1), measures resistance between a pair of transmission lines, DC voltage, noise level on the transmission line, and the like. Are sent to the wiring failure diagnosis manager. The wiring failure diagnosis manager compares the measured value with a predetermined threshold value, and when it is larger or smaller than the threshold value, determines that the transmission line is abnormal, and reports the type of abnormality to the user (Patent Document 1 FIG. 4A, 4B, FIG. 5).

  The wiring failure detection unit and the wiring failure diagnosis manager are provided in the linking device 44. Since the user can know the occurrence of the transmission line abnormality in the specific segment 48 and the type of the abnormality by the report, the cause of the abnormality is removed without investigating the transmission line of the other segment 53, and the communication is performed. Can solve obstacles.

JP 2003-44133 A

  However, in the operation of the wiring defect detection unit and the wiring defect diagnosis manager, since the user knows the abnormality of the transmission line after the occurrence, the occurrence of the abnormality is predicted in advance to prevent the occurrence of the communication failure. In some cases, it is difficult to improve the reliability of measurement, communication, control, and the like of the field device system 54.

In addition, a communication failure may occur when a field device such as the differential pressure transmitter 45, the host device 6 or the like malfunctions or malfunctions. For example, when a communication circuit component (not shown) inside a field device that is not directly connected to the transmission line deteriorates in performance and causes a communication failure, the resistance between the pair of transmission lines, the DC voltage, and the transmission line The noise level or the like may not exceed a threshold value. At this time, the wiring failure detection unit and the wiring failure diagnosis manager cannot report the abnormality of the transmission line to the user, and the user cannot know the cause of the communication failure. You may need it.

  Further, for example, the transmission line may be inadvertently short-circuited at a terminal portion (not shown) of a field device such as the differential pressure transmitter 45 connected to the transmission line. At this time, even if the wiring failure detection unit and the wiring failure diagnosis manager report the transmission line abnormality to the user, if the user does not remove the short circuit, the communication failure continues and the communication function of the field device system 54 is activated. It cannot be recovered.

  The object of the present invention relates to an abnormality diagnosis of a field device system, and in particular, an occurrence of an abnormality such as an open or short of a transmission line is predicted in advance and a communication failure is prevented, thereby measuring, communicating, and controlling a field device system. It is an object of the present invention to provide a field device system and a method for improving the reliability.

In order to achieve such an object, the invention of claim 1
In a field device system including a diagnostic module for detecting an abnormality in a transmission line,
The diagnostic module includes:
At least one measurement unit for measuring electrical characteristics of the transmission line;
A threshold value calculation unit for calculating a threshold value based on an initial measurement value of the measurement unit;
A comparison unit for comparing the measurement value of the measurement unit with the threshold value;
An alarm output unit that outputs an alarm based on the output of the comparison unit;
A storage unit for storing the measurement value of the measurement unit together with time information;
With a communication unit that communicates with external devices,
It is characterized by that.

The invention of claim 2 is the invention of claim 1,
The diagnostic module includes:
Furthermore, based on past measurement values and time information stored in the storage unit, the prediction unit predicts that the current measurement value reaches the threshold when a predetermined time has passed,
It is characterized by that.

The invention according to claim 3 is the invention according to claim 1 or 2,
The diagnostic module includes:
In addition, it has a communication analysis unit that calculates the number or rate of communication errors in field devices.
It is characterized by that.

The invention of claim 4 is the invention according to any one of claims 1 to 3,
The diagnostic module includes:
Connected to the transmission line to which one of the field devices is connected,
Furthermore, provided with an opening and closing unit for connecting or disconnecting the transmission line based on the alarm output,
It is characterized by that.

The invention of claim 5
In a diagnostic method for detecting an abnormality in a transmission line constituting a field device system,
Measuring electrical characteristics of the transmission line by a measurement unit;
Calculating a threshold based on an initial measurement value of the measurement unit;
Comparing the measurement value of the measurement unit with the threshold value;
Outputting an alarm based on the compared results;
Storing the measurement value of the measurement unit together with time information;
Comprising the step of communicating with an external device,
It is characterized by that.

The invention of claim 6 is the invention of claim 5,
The diagnostic method includes:
Furthermore, based on the stored past measurement value and time information, the step of predicting that the current measurement value reaches the threshold when a predetermined time has passed,
It is characterized by that.

The invention of claim 7 is the invention according to claim 5 or 6,
The diagnostic method includes:
Furthermore, a step of calculating the number or rate of communication errors of the field device is provided.
It is characterized by that.

  According to the present invention, field device system abnormality diagnosis, in particular, occurrence of abnormalities such as transmission line opening and short-circuiting is predicted in advance, and communication failure is prevented from occurring, and field device system measurement, communication, and control are performed. Thus, it is possible to realize a field device system and method for improving reliability.

[First embodiment]
The first embodiment will be described with reference to FIGS. FIG. 1 shows a field device system 22 showing a first embodiment of the present invention. The same components as those in FIG. FIG. 2 is a block diagram of the diagnostic module 20.

In FIG. 1, a diagnostic module 20 is connected to transmission lines 1, 21, 2 between a DC power supply 3 and a plurality of field devices 9, 10, 11.

  Specifically, the terminal A of the diagnostic module 20 is connected to the transmission line 1, the terminal B is connected to the transmission line 21, and the terminal C is connected to the transmission line 2. A terminator 5 is connected to the transmission lines 21 and 2, and a differential pressure transmitter 9 which is one of field devices is connected to the transmission lines 7 and 8 branched from the transmission lines 21 and 2. Similarly, the temperature transmitter 10 and the vortex flowmeter 11 are connected to a transmission line branched from the transmission lines 21 and 2.

  2, the diagnostic module 20 includes a power generation unit 24, a measurement unit 25, a selection unit 33, a threshold value calculation unit 26, a comparison unit 27, an alarm output unit 28, a control unit 29, a communication unit 34, a time timer 35, and a storage unit. 36.

  The power supply generation unit 24 is connected to the terminals A and C, generates an internal power supply voltage S4 from the output voltage of the DC power supply 3, and supplies it to each unit such as the measurement unit 25.

  The measuring unit 25 is connected to terminals A, B, C, the output of the communication unit 34, and the like, and from a meter that measures the electrical characteristics of the transmission lines 1, 21, 2 such as the voltmeter 30, the ammeter 31, and the noise meter 32. It includes a resistance meter, a capacitance meter, an oscilloscope (not shown), and the like.

The voltmeter 30 measures the DC voltage between the transmission lines 1 and 2 via the terminals A and C, and measures the peak-to-peak voltage of the communication waveform output from the communication unit 34. The ammeter 31 is connected between the terminals A and B, and measures the transmission line current flowing in the transmission lines 1, 21 and 2 including the current flowing in the differential pressure transmitter 9 and the like. The noise meter 32 measures the noise level on the transmission line 1. The resistance meter and the capacitance meter measure the resistance and capacitance between the transmission lines 1 and 2, and the oscilloscope measures the voltage waveform between the transmission lines 1 and 2, the communication waveform of the output of the communication unit 34, and the like.

  The selection unit 33 is connected to the output of the voltmeter 30 or the like constituting the measurement unit 25, and selects one of the measurement values measured by the voltmeter 30 or the like based on the switching signal output from the control unit 29. Select and output. The control unit 29 can also be realized by causing a microprocessor (not shown) to operate according to the flowchart of FIG. 6 based on a computer program (not shown).

  The threshold calculator 26 calculates and outputs a threshold S3 based on the initial measurement value S1 selected by the selector 33. The comparison unit 27 compares the threshold value S3 with the measurement value S2 selected by the selection unit 33. The alarm output unit 28 outputs an alarm based on the output of the comparison unit 27. The output of the alarm output unit 28 is connected to an acoustic device such as a buzzer or a lamp or a lighting device (not shown). In addition, the structure provided with the some threshold value calculating part, the comparison part, and alarm output part which are not provided with the selection part 33 but are connected to each output of the voltmeter 30, the ammeter 31, and the noise meter 32 may be sufficient.

  The time timer 35 has time information including the current date and time. The storage unit 36 is connected to the output of the selection unit 33, the output of the time timer 35, and the control unit 29.

  The memory | storage part 36 memorize | stores measured value S2 with the said time information. Further, data “1” may be stored when an alarm is output, and data “0” may be stored when an alarm is not output.

  The communication unit 34 is connected to the terminals A and C and the control unit 29. The communication unit 34 receives a communication signal for requesting information included in the diagnostic module 20 from the host device 6 that is an external device via the transmission lines 1 and 2. Based on the received signal, the control unit 29 receives the information from the storage unit 36, and the communication unit 34 transmits it to the host device 6. The information is time information and measurement values stored in the storage unit 36, and may further include alarm output data.

  The selection unit 33, the threshold value calculation unit 26, the comparison unit 27, the alarm output unit 28, the control unit 29, the time timer 35, and the communication unit 34 cause the microprocessor to operate according to the flowchart of FIG. 6 based on the computer program. Can also be realized.

  The operation of the diagnostic module 20 including the diagnostic method will be described using the flowchart of FIG.

  By outputting the voltage of the DC power supply 3, a voltage is applied to the terminals A and C of the diagnostic module 20 (step F1), and the diagnostic module 20 executes step F2 and subsequent steps.

  A voltmeter 30, an ammeter 31, a noise meter 32, etc. constituting the measuring unit 25 perform initial measurement of the electrical characteristics of the transmission lines 1, 21, 2 (step F 2). One of them is selected (step F3).

The selected initial measurement value S1 is input to the threshold value calculation unit 26, and the threshold value calculation unit 26 calculates the threshold value S3 by adding or subtracting the variation to the initial measurement value S1 (step F4). The threshold value S3 may be changed and set.

  If the threshold value S3 is not calculated based on the initial measured values S1 of all the electrical characteristics, step F3 and subsequent steps are repeated, and if calculated, step F6 and subsequent steps are executed (step F5).

  A voltmeter 30, an ammeter 31, a noise meter 32, etc. constituting the measurement unit 25 measure the electrical characteristics of the transmission lines 1, 21, 2 (step F 6), and the selection unit 33 selects one of the measured values. One is selected (step F7).

  The comparison unit 27 compares the threshold value S3 with the selected measurement value S2 (step F8). If measured value S2 is larger or smaller than threshold value S3, it is detected that there is an abnormality in the transmission line (step F13), and alarm output unit 28 outputs an alarm based on the output of comparison unit 27 (for example, about 5 volts). (Step F14). Then, the user can know that there is an abnormality in the transmission line by sound and light emitted from a buzzer, a lamp, or the like connected to the output of the alarm output unit 28.

  For example, the threshold values of the DC voltage between the transmission lines 1 and 2 are 20.8 volts and 21.2 volts, and an alarm is output if the measured value S2 is less than 20.8 volts or greater than 21.2 volts. (Step F14). Similarly, the peak-to-peak voltage thresholds of the communication waveform are 0.8 volts and 1.2 volts.

  On the other hand, if the measured value S2 is not larger or smaller than the threshold value S3 (for example, the DC voltage is in the range of 20.8 volts to 21.2 volts), it is detected that there is no abnormality in the transmission line (step F9). The alarm is not output (step F10), and the storage unit 36 stores the measured value S2 together with the time information of the time timer 35 (step F11).

  After the process of step F11 or step F14 is performed, the process proceeds to step F15 (prediction process (step F12) will be described later). Note that the storage unit 36 may store the alarm output data ("1" or "0") before step F15 is processed.

  If the measured value S2 of all electrical characteristics and the threshold value S3 are not compared, step F7 and subsequent steps are repeated, and if compared, step F6 and subsequent steps are repeated (step F15). By these processes, the measured value S2 of all electrical characteristics is compared with the threshold value S3, transmission line abnormality diagnosis, storage, and the like are performed.

  The communication processing (not shown in FIG. 6) between the host device 6 and the diagnostic module 20 is stored in the storage unit 36 via the communication unit 34 based on a communication signal from the host device 6 that is regular or irregular. Information is transmitted to the host device 6.

  In FIG. 9, when the transmission line absorbs the influence of the surrounding environment, for example, in a high humidity environment, the insulation degradation of the transmission lines 7 and 8 connected to the differential pressure transmitter 9 proceeds, and the current flowing through the transmission line is The case where it increases gradually is demonstrated.

  For example, the transmission line current measured by the ammeter 31 seven days before the present was Curp, but the transmission line current gradually increased with the progress of the insulation deterioration, and now becomes Curt. Since it is smaller than the threshold value at the present time point, it is not diagnosed that the transmission line is abnormal. However, the user sees the time information and the transmission line current transmitted from the diagnosis module 20 in the host device 6, so that It can be predicted that the transmission line current becomes larger than the threshold value within the range, and it can be diagnosed that the transmission line is abnormal.

  Then, before the transmission line malfunctions and communication failure occurs, the user investigates the insulation resistance of the transmission lines 7 and 8 based on the prediction, and if the resistance is small, replace the transmission line. Therefore, it is possible to prevent the occurrence of communication failure and improve the reliability of communication of the field device system.

  According to this embodiment, the user predicts the occurrence of an abnormality such as an open circuit or a short circuit in advance in connection with an abnormality diagnosis of a field device system in advance, prevents the occurrence of a communication failure, and measures the measurement and communication of a field device system. , Reliability of control and the like can be improved.

[Second Embodiment]
A second embodiment will be described with reference to FIG. FIG. 3 is a block diagram of the diagnostic module 20, and the same components as those in FIG.

  In FIG. 3, the prediction unit 37 is connected to the storage unit 36 and the control unit 29. The prediction unit 37 acquires a measurement value a predetermined number of days before from the storage unit 36, and predicts whether or not the threshold value is reached when the current measurement value has passed a predetermined time. Based on the communication signal from the host device 6, the diagnostic module 20 transmits the prediction result to the host device 6 via the control unit 29 and the communication unit 34. The prediction unit 36 can also be realized by causing the microprocessor to operate according to the flowchart of FIG. 7 based on the computer program.

  The operation of the prediction unit 37 will be described using the flowchart of FIG. 7 and FIG. 9 including the diagnostic method. FIG. 9 shows a situation where the transmission lines 7 and 8 are deteriorated in insulation as described above.

  The prediction process performed in step F12 of FIG. 6 is to predict the transmission line current after seven days when the transmission line current seven days before from the present is Curp and increases to Curt at the present, for example.

  The prediction unit 37 acquires the measured value Curp of the transmission line current seven days before from the current time based on the stored time information from the storage unit 36 (step F16), and the amount of change between the current value and the measured value seven days ago. ΔCur (= Curt−Cutp) is calculated (step F17).

  Further, the prediction unit 37 calculates the predicted measurement value Curn after 7 days by adding the change amount ΔCur to the current measurement value Curt (step F18). If the predicted measurement value Curn is greater than the threshold value (step F19), it is predicted that the current measurement value Curt will reach the threshold value within 7 days (step F20), and if it is smaller, it is predicted that it will not be reached (step F21). Put out.

  Based on the communication signal from the host device 6, the diagnostic module 20 transmits the prediction result to the host device 6 via the communication unit 34.

In the host device 6, the user knows from the prediction result that a transmission line abnormality will occur in the future and a communication failure may occur, and before that occurs, the insulation resistance of the transmission lines 7 and 8 is investigated, and the resistance If the distance is smaller, the occurrence of communication failure can be prevented by exchanging the transmission line, and the reliability of communication of the field device system can be improved.

  According to this embodiment, the user can prevent the occurrence of a communication failure by obtaining a prediction result that may cause an abnormality such as an open or short of a transmission line, in particular, regarding an abnormality diagnosis of a field device system. Reliability of measurement, communication, control, etc. can be improved. In addition, since the diagnosis module 20 makes the prediction, it is possible to reduce the burden of monitoring the measurement value of the user.

[Third embodiment]
A third embodiment will be described with reference to FIG. FIG. 4 is a block diagram of the diagnostic module 20, and the same components as those in FIGS. In general, the host device 6 sends a communication signal to a specific field device and obtains a response signal from the field device.

  In FIG. 4, the communication analysis unit 38 is connected to the communication unit 34 and the control unit 29. The communication analysis unit 38 acquires a communication signal for a specific field device from the host device 6 via the communication unit 34, and calculates the number and rate of communication errors that the field device does not respond to the communication signal. .

Then, the diagnosis module 20 transmits the number and ratio of the communication errors to the host device 6 via the control unit 29 and the communication unit 34 based on the communication signal from the host device 6. The prediction unit 36 can also be realized by causing the microprocessor to operate according to the flowchart of FIG. 8 based on the computer program.

  The operation of the communication analysis unit 38 including the diagnosis method will be described using the flowchart of FIG. The process of FIG. 8 is performed when the diagnostic module 20 receives a communication signal from the host device 6.

  The communication unit 34 receives a communication signal for a specific field device from the host device 6 (step F22), and the communication analysis unit 38 acquires the received signal from the communication unit 34 and includes a communication partner included in the received signal. The destination field device is specified by examining the address and the like (step F23).

  Further, the communication analysis unit 38 waits for a response signal from the counterpart field device (step F24). If there is a response, the communication analysis unit 38 increases the number of times of no communication error of the field device by one (step F27). Step F28 is executed. If there is no response and a predetermined time (for example, 1 minute) has not elapsed (step F25), step F24 is repeated, and if it has elapsed, the number of times that the field device has a communication error is increased by 1 (step F26). ). Then, the communication error ratio of the field device is calculated by dividing the number of communication errors by the total number of communication errors and no communication errors (step F28).

  Based on the communication signal from the host device 6, the diagnostic module 20 transmits the identification number of each field device, the number of communication errors, and the communication error ratio to the host device 6 via the communication unit 34. .

When the characteristics of the components of the communication circuit in the field device deteriorate, there is no response signal from the field device, and frequent communication failures occur, the user can use the host device 6 to count the number of communication errors. Knowing that the ratio is large, it is possible to know the specific field device that is the cause of the communication failure by referring to the identification number. Therefore, by exchanging the field device with less man-hours for investigating the cause, it is possible to suppress the occurrence of a communication failure and improve the reliability of communication of the field device system.

  According to the present embodiment, the user can obtain information on field device system abnormality diagnosis, in particular, information on communication errors of the field device, thereby suppressing the occurrence of communication failure and improving the reliability of measurement, communication, control, etc. of the field device system. Can be improved. In addition, the user can reduce the burden of investigating the cause of communication failure.

[Fourth embodiment]
A connection between the diagnostic module 20 and the transmission line is different from that shown in FIG. 1, and a fourth embodiment having an opening / closing portion is described with reference to FIG. In FIG. 5, the same components as those in FIG.

  Specifically, the terminal A of the diagnostic module 20 is connected to the transmission line 7, the terminal B is connected to the transmission line 39, and the terminal C is connected to the transmission line 8. The opening / closing unit 43 is connected to the transmission lines 39, 8 and the output of the alarm output unit 28 of the diagnostic module 20, and is connected to the differential pressure transmitter 9 via the transmission lines 41, 42.

In Step F9 of FIG. 6, it is detected that there is no abnormality in the transmission line, and the opening / closing unit 43 determines that the transmission lines 39, 8 and 41, 41 are based on the output of the alarm output unit 28 (for example, a voltage signal of about 0 volts). 42 is connected. Also, it is detected that there is an abnormality in the transmission line (step F13), and the opening / closing unit 43 is based on the output of the alarm output unit 28 (for example, a voltage signal of about 5 volts), and the transmission lines 39, 8 and 41, 42. Disconnect. And the alarm output part 28 maintains the output continuously, and the opening-and-closing part 43 maintains the state which cut | disconnected the transmission lines 39,8 and 41,42. Note that the opening / closing part 43 may be connected in series between the terminals A and B in the diagnostic module 20.

  For example, the transmission line may be inadvertently short-circuited at a terminal portion (not shown) of the differential pressure transmitter 9 connected to the transmission line. At this time, since a current larger than the threshold value flows in the transmission lines 7, 41, 42, and 8, the current diagnosis module 20 detects that there is an abnormality in the transmission line in Step F13 of FIG. Then, the open / close unit 43 can cut the transmission lines 39, 8 and 41, 42 based on the output of the alarm output unit 28 and remove the short-circuited transmission line, and the field device system 40 can perform communication. it can.

  According to the present embodiment, the diagnostic module 20 and the opening / closing unit 43 automatically disconnect the transmission line causing the transmission line abnormality, thereby preventing the occurrence of a communication failure and measuring, communicating, and controlling the field device system. It is possible to improve reliability. In addition, it is possible to reduce the burden of investigating the cause when a communication failure occurs and restoring the communication.

  Note that the diagnostic module 20 or the diagnostic method of the present invention may be provided inside a host device 6, a field device such as the differential pressure transmitter 9, or a portable device.

It is a block diagram which shows one Example of this invention. 3 is a block diagram illustrating a specific example of a diagnostic module 20. FIG. It is a block diagram which shows the other specific example of the diagnostic module 20. FIG. It is a block diagram which shows the other specific example of the diagnostic module 20. FIG. It is a block diagram which shows the other Example of this invention. 4 is a flowchart showing the operation of the diagnostic module 20. 4 is a flowchart illustrating a prediction processing unit in the operation of the diagnosis module 20. 4 is a flowchart illustrating a communication analysis processing unit in the operation of the diagnosis module 20. It is an example of the characteristic with respect to time of the transmission line current by the influence of surrounding environment. It is a block diagram which shows an example of the past.

Explanation of symbols

2, 7, 8, 21 Transmission line 3 DC power supply terminator 6 Host device 9 Differential pressure transmitter 10 Temperature transmitter 11 Vortex flow meter 20 Diagnostic module 22 Field device system 24 Power generation unit 25 Measurement unit 26 Threshold calculation unit 27 Comparison unit 28 alarm output unit 29 control unit 30 voltmeter 31 ammeter 32 noise meter 33 selection unit 34 communication unit 35 time timer 36 storage unit 37 prediction unit 38 communication analysis unit

Claims (7)

In a field device system including a diagnostic module for detecting an abnormality in a transmission line,
The diagnostic module includes:
At least one measurement unit for measuring electrical characteristics of the transmission line;
A threshold value calculation unit for calculating a threshold value based on an initial measurement value of the measurement unit;
A comparison unit for comparing the measurement value of the measurement unit with the threshold value;
An alarm output unit that outputs an alarm based on the output of the comparison unit;
A storage unit for storing the measurement value of the measurement unit together with time information;
With a communication unit that communicates with external devices,
A field device system characterized by that. The diagnostic module includes:
Furthermore, based on past measurement values and time information stored in the storage unit, the prediction unit predicts that the current measurement value reaches the threshold when a predetermined time has passed,
The field device system according to claim 1. The diagnostic module includes:
In addition, it has a communication analysis unit that calculates the number or rate of communication errors in field devices.
The field device system according to claim 1, wherein the field device system is a device. The diagnostic module includes:
Connected to the transmission line to which one of the field devices is connected,
Furthermore, provided with an opening and closing unit for connecting or disconnecting the transmission line based on the alarm output,
The field device system according to any one of claims 1 to 3, wherein In a diagnostic method for detecting an abnormality in a transmission line constituting a field device system,
Measuring electrical characteristics of the transmission line by a measurement unit;
Calculating a threshold based on an initial measurement value of the measurement unit;
Comparing the measurement value of the measurement unit with the threshold value;
Outputting an alarm based on the compared results;
Storing the measurement value of the measurement unit together with time information;
Comprising the step of communicating with an external device,
A diagnostic method characterized by that. The diagnostic method includes:
Furthermore, based on the stored past measurement value and time information, the step of predicting that the current measurement value reaches the threshold when a predetermined time has passed,
The diagnostic method according to claim 5. The diagnostic method includes:
Furthermore, a step of calculating the number or rate of communication errors of the field device is provided.
The diagnostic method according to any one of claims 5 and 6, wherein:

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