JP2014222372A - Field apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a field apparatus that predicts, at a field apparatus side, a possibility that communication failure will occur in the future, and gives notice to an upper-level apparatus.SOLUTION: A field apparatus 10 configured to communicate with an upper-level apparatus 20 is provided with communication speed diagnosis means 121 for diagnosing the speed of communication performed between the upper-level apparatus 20 and the field apparatus 10.

Description

  The present invention relates to field devices, and more particularly to diagnosis of communication quality.

  FIG. 6 is a block diagram illustrating a general connection example of field devices. In FIG. 6, a field interface 10 such as a thermometer, a pressure transmitter, and a valve positioner is provided with a communication interface 11 for communicating with a host device 20, and a CPU 12 is connected to the communication interface 11. Has been. The CPU 12 is connected to a predetermined sensor 13 corresponding to each measurement target such as the temperature, pressure, and flow rate of the field device 10 and a memory 14.

  When the field device 10 analyzes the communication data transmitted from the host device 20 by the CPU 12 and detects abnormal communication data such as a framing error, a parity error, and an overrun error, the field device 10 gives a predetermined alarm to the host device 20. Send to.

  By the way, if a problem occurs in communication between the field device 10 and the host device 20, it takes time to recover the communication state and analyze the cause, which affects the operation of the plant during that time.

  Patent Document 1 describes a technology of a communication quality diagnostic apparatus that detects a precursor phenomenon and outputs an alarm at an early stage before a communication failure due to noise becomes apparent.

JP 2009-100801 A

  However, in the conventional field device 10, no special measures are taken to minimize the influence on the operation of the plant due to the occurrence of a communication failure with the host device 20, and a communication failure occurs. If this occurs, it may be possible to deal with an alternative field device, for example.

  However, if the plant system is composed of multiple types of field devices, preparing all types of alternative field devices is likely to result in wasted capital investment, which is not practical. Absent.

  The present invention solves such a problem, and an object of the present invention is to predict the possibility of a communication failure in the future on the field device side and notify the higher-level device.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In field devices configured to communicate with the host device,
The field device is provided with communication speed diagnosis means for diagnosing the speed of communication with the host device.

The invention according to claim 2 is the field device according to claim 1,
The communication speed diagnosis means includes
A communication speed detector for detecting a communication speed of predetermined communication data sent from the host device;
A communication speed abnormality determination unit that determines a communication speed abnormality when a communication speed detected by the communication speed detection unit exceeds a predetermined threshold;
A communication speed abnormality notifying unit for notifying the host device of a communication speed abnormality determination result of the communication speed abnormality determining unit;
It is comprised by these.

The invention according to claim 3 is the field device according to claim 1 or 2,
The communication speed diagnosis means includes
When the communication data is frequency-modulated, a communication speed abnormality is diagnosed based on the communication speed of one frame.

According to a fourth aspect of the present invention, in the field device according to any one of the first to third aspects,
The communication speed diagnosis means includes
The field device predicts the possibility of a communication failure in the future and notifies the host device.

  As a result, the field device can always monitor the communication speed of communication data, so it can detect minute noise that does not cause a communication error, and predicts the possibility of a communication failure in the future on the field device side. Can be notified.

It is a block diagram which shows one Example of this invention. It is a block diagram which shows the specific structural example of the communication speed detection part 121 of FIG. 3 is a timing chart for explaining the operation of FIG. 2. It is a specific example figure of the communication data based on a HART communication system. It is a block diagram which shows the specific structural example of the communication speed diagnostic part 121 used with a HART communication system. It is a block diagram which shows the example of a general connection of field equipment.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and the same reference numerals are given to portions common to FIG. In FIG. 1, the CPU 12 is provided with a communication speed diagnosis unit 121.

  FIG. 2 is a block diagram illustrating a specific configuration example of the communication speed diagnosis unit 121 of FIG. In FIG. 2, the communication speed diagnosis unit 121 includes a communication speed detection unit 121a, a communication speed abnormality determination unit 121b, and a communication speed abnormality notification unit 121c.

  The communication speed detection unit 121a monitors and detects the “transmission time for 1 byte” of the communication data sent from the host device 20.

  The communication speed abnormality determination unit 121b determines that the diagnosis result is abnormal when the detected communication speed exceeds a predetermined threshold.

  When the communication speed abnormality notification unit 121c determines abnormality as a diagnosis result, the communication speed abnormality notification unit 121c notifies the upper apparatus 20 of the result as an alarm.

  The operation of the communication speed diagnosis unit 121 configured as shown in FIG. 2 will be described using the timing chart of FIG. 3A shows one frame of communication data sent from the host device 20 to the field device 10, and FIG. 3B shows one byte of communication data sent from the host device 20 to the field device 10. D0, D1,..., Dn are shown.

  The communication speed detector 121a records the timing when reception of the communication data D0, D1,..., Dn for 1 byte shown in FIG. The detection time td until it is measured is measured. Then, the communication speed is calculated from the detection time td and stored in the memory 14.

  The communication speed abnormality determination unit 121b determines whether the communication speed detected by the communication speed detection unit 121a exceeds a predetermined threshold. Further, the average value and standard deviation of the communication speed in one frame are also used as judgment criteria.

  The communication speed abnormality notifying unit 121c notifies the higher-level device 20 of the result determined as a diagnostic abnormality by the communication speed abnormality determining unit 121b as an alarm.

  And even if the communication speed detected by the communication speed detection unit 121a does not exceed a predetermined threshold, the communication speed abnormality notification unit 121c records changes in the communication speed, etc. It is possible to predict the possibility of a communication failure in the future and notify the host device.

  As a result, appropriate trouble prevention measures such as replacement of the corresponding field equipment can be taken at the occasion of periodic inspection before the trouble occurs in communication between the field equipment 10 and the host device 20, and the plant Can maintain long-term stable operation.

  In the case of a HART (Highway Addressable Remote Transducer) (registered trademark) communication system configured to transmit a large number of signals by superimposing a digital signal on a DC 4 to 20 mA signal, communication is performed because of frequency modulation. The transmission time for one byte of data differs depending on the data. Therefore, in this case, an abnormality is detected by calculating the communication speed of one frame.

  An abnormality detection operation in the HART communication system will be described with reference to FIGS.

  FIG. 4 is a specific example of communication data based on the HART communication system, and a digital signal sequence “100110110” is superimposed on a DC 4 to 20 mA signal.

  FIG. 5 is a block diagram showing a specific configuration example of the communication speed diagnostic unit 121 used in the HART communication system, and the same reference numerals are given to the parts common to FIG. The difference between FIG. 5 and FIG. 2 is that a communication speed calculation unit 121d is added to the communication speed diagnosis unit 121 of FIG. In FIG. 5, the communication speed detection unit 121a is connected to the communication speed abnormality determination unit 121b and to the communication speed calculation unit 121d. The communication speed calculation unit 121d is connected to the communication speed abnormality determination unit 121b.

  The communication speed detecting unit 121a acquires the received data (100110110) and the “actual value” of the communication time of one frame and outputs the received data (100110110) to the communication speed calculating unit 121d. Output.

  The communication speed calculation unit 121d calculates a communication speed of one frame from the received data, obtains a “calculated value” of the communication speed, and outputs it to the communication speed abnormality determination unit 121b.

  The communication speed abnormality notification unit 121c determines whether or not there is an abnormality by taking in and comparing the "actual value" acquired by the communication speed detection unit 121a and the "calculated value" obtained by calculation by the communication speed abnormality determination unit 121b, When an abnormality determination is made as a diagnosis result, the result is notified to the host device 20 as an alarm.

  As described above, according to the field device according to the present invention, it is possible to detect minute noise that does not cause a communication error by constantly monitoring the communication speed of communication data, and a communication failure will occur in the future on the field device side. A field device that can predict the possibility and notify the higher-level device can be realized.

10 Field device 11 Communication interface 11
12 CPU
121 Communication speed diagnosis unit 121a Communication speed detection unit 121b Communication speed abnormality determination unit 121c Communication speed abnormality notification unit 121d Communication speed calculation unit 13 Sensor 14 Memory 20 Host device

Claims (4)

In field devices configured to communicate with the host device,
A field device characterized in that the field device is provided with communication speed diagnosis means for diagnosing the speed of communication with the host device. The communication speed diagnosis means includes
A communication speed detector for detecting a communication speed of predetermined communication data sent from the host device;
A communication speed abnormality determination unit that determines a communication speed abnormality when a communication speed detected by the communication speed detection unit exceeds a predetermined threshold;
A communication speed abnormality notifying unit for notifying the host device of a communication speed abnormality determination result of the communication speed abnormality determining unit;
The field device according to claim 1, comprising: The communication speed diagnosis means includes
3. The field device according to claim 1, wherein when the communication data is frequency-modulated, a communication speed abnormality is diagnosed based on a communication speed of one frame. The communication speed diagnosis means includes
The field device according to any one of claims 1 to 3, wherein the field device predicts a possibility of a communication failure in the future and notifies the host device.