JP5825480B2 - Field wiring diagnosis device - Google Patents

Description

  The present invention relates to a field wiring diagnosis device including a short-circuit diagnosis unit for diagnosing a short-circuit abnormality up to a field device that operates when a power supply voltage is supplied via a switch unit operated by a digital output module. INDUSTRIAL APPLICABILITY The present invention is effectively applied as a short-circuit abnormality diagnosis device for solenoid valves, relays, and the like that are operated in a binary manner via a digital output module in a safety control system.

  FIG. 5 is a functional block diagram illustrating a configuration example of the digital output module in the safety control system. The host device 10 of the safety control system 1 communicates with the digital output module 30 via the control bus 20 and transmits an operation command for field devices based on a trip request from the plant to the control unit 40 of the digital output module 30.

  The digital output module 30 is connected to a DC 24V external power source E and a plurality of field devices F1, F2,... Fn, and the external power source E is connected to the field devices F1, F2,. And is operated in a binary manner.

  The control unit 40 generates a signal M for turning on the switch means connected to the field device to be tripped based on the trip command passed from the host device 10 at a predetermined control cycle.

  The control unit 40 includes a short-circuit diagnosis unit 50 for periodically monitoring a short-circuit abnormality to the field devices F1, F2,... Fn and outputting abnormality detection information AL in order to ensure the reliability of the safety control system. ing. A digital output device having a field wiring short-circuit diagnosis function is disclosed in Patent Document 1.

  The short-circuit diagnosis unit 50 operates the switch means S1, S2,... Sn with a test pulse P using a time period between the control cycles of the control unit 40 for a predetermined time, and causes the field devices F1, F2,. The flowing current value is acquired as the read-back current value i1, i2,... In via the current detection means R1, R2,... Rn, the acquired read-back current value is compared with the short-circuit detection set value, and the read-back current value is short-circuited. When the detection set value is exceeded, abnormality detection information AL is output.

  FIG. 6 is a functional block diagram illustrating a configuration example of the conventional short-circuit diagnosis unit 50. For simplicity, one channel by the switch means S1 and the field device F1 is shown as a representative. The short circuit diagnosis unit 50 includes a pulse output unit 51, a short circuit diagnosis unit 52, and a short circuit detection value setting unit 53.

  When the switch means S1 is turned on by the test pulse P from the pulse output means 51, the current flowing through the field device F1 is detected by the current detection means R1, and the read back current value i1 is input to the short-circuit diagnosis means 52.

  The short-circuit diagnosis means 52 externally outputs the abnormality detection information AL when the fixed short-circuit detection value Is is set and inputted by the short-circuit detection value setting means 53 and the read-back current value i1> short-circuit detection value Is.

JP 2006-209618 A

The conventional apparatus has the following problems.
(1) FIG. 7 is an explanatory diagram of a short circuit detection operation in a conventional field wiring diagnostic device. Even if the wiring is normal, if a field device with inrush current characteristics is connected, an excessive current is generated at the timing of the pulse test.

  The short-circuit diagnosis means 52 must set the short-circuit detection value Is to a value higher than the assumed inrush current value i1 as shown in FIG. .

(2) On the other hand, since the current value in the event of a short circuit is limited by the wiring resistance of the field wiring, the pulse test read-back current at the time of the short circuit is detected so that a short circuit abnormality can be detected when wiring the field device and the module. > It must be wired to meet the short circuit detection value.

  Accordingly, there is a problem that the wiring distance (wiring resistance) is limited when the short circuit detection value is set high in order to avoid erroneous detection due to inrush current. As a countermeasure, there may be a means to change the setting of the short circuit detection value for each channel according to the inrush current value of the field device, but when it is set near the pulse test read-back current, the wiring resistance due to fluctuations in external power supply voltage or temperature fluctuation The inrush current value fluctuates due to the fluctuation, and there is a possibility that a short circuit abnormality is erroneously detected as shown in FIG.

  An object of the present invention is to realize a field wiring diagnosis apparatus that relaxes the wiring distance limitation for field devices having inrush current characteristics and does not erroneously detect inrush current fluctuations due to external factors.

In order to achieve such a subject, the present invention has the following configuration.
(1) In a field wiring diagnosis apparatus including a short-circuit diagnosis unit for diagnosing a short-circuit abnormality up to a field device that operates by supplying a power supply voltage via a switch unit operated by a digital output module.
The short-circuit diagnosis unit
Pulse output means for operating the switch means for a predetermined time in a diagnostic mode;
A short-circuit detection value for generating a short-circuit detection value by receiving a read-back current flowing through the field device while the switch means is on and generating a current reference value corresponding to the read-back current value and adding an offset value to the current reference value Generating means;
Short-circuit diagnosis means for inputting the read-back current value and the short-circuit detection value;
A field wiring diagnostic apparatus comprising:

(2) The short-circuit detection value generating means is a filter means for moving and averaging the values of the input read-back current value for a predetermined period, holds the output of the filter means, updates the short-circuit detection value, and outputs it. The field wiring diagnosis device according to (1), further comprising a current reference value holding unit.

(3) The short circuit detection value generating means includes offset value setting means for adding a predetermined offset value to the output value of the current reference value holding means, and the offset value is based on the output of the current reference value holding means. The field wiring diagnostic device according to (2), wherein the field wiring diagnostic device is changed.

(4) The short-circuit detection value generating means includes a filter means for inputting a read power supply voltage value of the power supply voltage and moving average, a power supply reference value holding means for updating and holding the output of the filter means, and the power supply A division means for calculating a ratio between a read-back power supply voltage value and an output value of the power supply reference value holding means, and input to the output value of the current reference value holding means or the short-circuit diagnosis means according to the calculated ratio The field wiring diagnostic device according to (2) or (3), wherein the read-back current value is corrected.

(5) The field according to any one of (2) to (4), wherein the short circuit detection value generation unit includes a limit processing unit that limits an output value of the current reference value holding unit with a predetermined value. Wiring diagnostic device.

(6) An update stop means for stopping update processing of the current reference value holding means based on the abnormality detection information from the diagnosis means or the abnormality detection information of another channel is provided (2) to (5) The field wiring diagnostic apparatus in any one of.

According to the present invention, the following effects can be expected.
(1) In the conventional device, the short circuit detection value is set to a high fixed value. However, in the present invention, the short circuit detection value is automatically updated according to the inrush current of the field device in the field. Is alleviated.

(2) Even if the external power supply voltage fluctuates and the inrush current fluctuates, the short circuit detection value is corrected by detecting the fluctuation, so that a short circuit abnormality is not erroneously detected.

(3) Even if the wiring resistance value fluctuates due to temperature fluctuations and the inrush current fluctuates, the current reference value is constantly updated, so the fluctuating inrush current value follows. For this reason, a short circuit abnormality is not erroneously detected due to temperature fluctuation.

(4) Even if noise is temporarily mixed and the inrush current fluctuates, the short circuit detection value does not fluctuate because it is generated by filtering. In general, the diagnosis includes a detection counter, and even if an error is counted several times due to noise, a short circuit abnormality is not erroneously detected.

(5) Since the updating of the reference value is stopped in the case of a channel abnormality, the short circuit detection value is not updated and not detected when a short circuit abnormality is detected.

It is a functional block diagram which shows one Example of the field wiring diagnostic apparatus to which this invention is applied. It is a functional block diagram which shows the structural example of a short circuit detection value production | generation means. It is a characteristic view of an offset value. It is a functional block diagram which shows the other Example of the field wiring diagnostic apparatus to which this invention is applied. It is a functional block diagram which shows the structural example of the digital output module in a safety control system. It is a functional block diagram which shows the structural example of the conventional short circuit diagnosis part. It is explanatory drawing of the short circuit detection operation | movement in the conventional field wiring diagnostic apparatus.

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

  6 is different from the conventional apparatus shown in FIG. 6 in that a read-back current value i1 is input dynamically instead of the short-circuit detection value setting means 53 that outputs the fixed short-circuit detection value Is to the short-circuit diagnosis means 52. The short circuit detection value generating means 100 for outputting the short circuit detection value If generated and automatically updated to the short circuit diagnosis means 52 is provided.

  Further, the short circuit detection value generation means 100 inputs a function for adjusting the offset value added to the short circuit detection value If based on the current reference value and the read power supply voltage value E and detects the fluctuation ratio in real time to detect the short circuit detection value. A function of correcting the read-back current value i1 input to the If or short-circuit diagnosis means 52 is provided.

  FIG. 2 is a functional block diagram illustrating a configuration example of the short circuit detection value generation unit 100. The short circuit detection value If is generated based on the current reference value output Io of the current reference value holding means 101. The filter unit 102 holds data before a predetermined period from the current value of the read-back current i1, calculates a moving average thereof, and passes it to the current reference value holding unit 101.

  With such a filtering process, the current reference value output Io of the current reference value holding means 101 does not fluctuate even if an inrush current at the time of test occurs in a short time and the read-back current i1 changes suddenly. Follows the slow fluctuation of the readback current i1 and is automatically updated with respect to the environmental fluctuation.

  The current reference value output Io of the current reference value holding unit 101 is added by the adding unit 104 with the offset value Q from the offset value setting unit 103. FIG. 3 is a characteristic diagram of the offset value. Since the current reference value varies depending on the wiring resistance, the offset value Q is a variable value having a predetermined ratio with respect to the level of the current reference value.

  The output of the adding means 104 to which the offset value is added is multiplied by the fluctuation ratio k of the external power source by the multiplying means 105, further limited by the limit processing means 106, and output to the short-circuit diagnosis means 52 as the short-circuit detection value If. Is done.

  The power supply reference value Eo is generated based on the output of the power supply reference value holding means 107. The filter unit 108 holds data before a predetermined period from the current value of the read-back power supply voltage value E, calculates the moving average thereof, and passes it to the power supply reference value holding unit 107.

  By such a filtering process, the power supply reference value output Eo of the power supply reference value holding means 107 does not fluctuate even if the voltage fluctuation of the external power supply occurs in a short time and the read power supply voltage E suddenly changes, but the power supply voltage is slow. Follows fluctuations and is automatically updated with environmental fluctuations.

  The ratio of the read back power supply voltage E and the power supply reference value output Eo is calculated by the dividing means, and the fluctuation ratio k of the power supply voltage E is calculated. The fluctuation ratio k corrects the current reference value Io by the multiplication means 105, thereby preventing a diagnosis error with respect to the power supply voltage fluctuation.

  FIG. 4 is a functional block diagram showing another embodiment of the field wiring diagnostic apparatus to which the present invention is applied. The difference from the embodiment shown in FIG. 2 is that the multiplication means 105 ′ multiplies the read-back current value i1 input to the short-circuit diagnosis means 52 by a ratio k. The short-circuit diagnosis unit 52 monitors the difference between the read-back current i1 and the short-circuit detection value If, and thus provides the same effect as in FIG.

  In the embodiment of FIGS. 2 and 4, the configuration of one channel of one field device is shown for simplicity, but the configuration of other channels is the same. The abnormality stopping unit 200 stops the automatic update of the current reference value holding unit 101 based on the abnormality detection information AL of the own channel or the abnormality detection information of another channel.

According to the present invention described above, the short circuit detection value is automatically updated in accordance with the inrush current of the field device in the field, so that the wiring distance limitation for the field device is relaxed. Furthermore, even if the external power supply voltage fluctuates and the inrush current fluctuates, the short circuit detection value is corrected by detecting the fluctuation, so that a short circuit abnormality is not erroneously detected.

  Further, even if the wiring resistance value fluctuates due to temperature fluctuations and the inrush current fluctuates, the current reference value is constantly updated, so that the fluctuating inrush current value is followed. For this reason, a short circuit abnormality is not erroneously detected due to temperature fluctuation.

  Even if noise is temporarily mixed and the inrush current fluctuates, the short circuit detection value does not fluctuate because it is generated by filtering. In general, the diagnosis includes a detection counter, and even if an error is counted several times due to noise, a short circuit abnormality is not erroneously detected.

  Since the update of the current reference value is stopped in the case of a channel abnormality, the short circuit detection value is not updated and no longer detected when a short circuit abnormality is detected.

DESCRIPTION OF SYMBOLS 1 Safety control system 10 Host apparatus 20 Control bus 30 Digital output module 40 Control part 50 Short-circuit diagnostic part 51 Pulse output means 52 Short-circuit diagnostic means 100 Short-circuit detection value generation means 101 Current reference value holding means 102 Filter means 103 Offset value setting means 104 Addition means 105, 105 'multiplication means 106 limit processing means 107 power supply reference value holding means 108 filter means 109 division means 200 update stop means

Claims (6)

In a field wiring diagnosis apparatus comprising a short-circuit diagnosis unit for diagnosing a short-circuit abnormality up to a field device that operates by supplying power supply voltage via a switch means operated by a digital output module,
The short-circuit diagnosis unit
Pulse output means for operating the switch means for a predetermined time in a diagnostic mode;
A short-circuit detection value for generating a short-circuit detection value by receiving a read-back current flowing through the field device while the switch means is on and generating a current reference value corresponding to the read-back current value and adding an offset value to the current reference value Generating means;
Short-circuit diagnosis means for inputting the read-back current value and the short-circuit detection value;
A field device wiring apparatus comprising:   The short-circuit detection value generating means is a filter means for moving and averaging the values of the input read-back current value for a predetermined period, and a current reference value that holds the output of the filter means and updates the short-circuit detection value and outputs it. The field wiring diagnosis apparatus according to claim 1, further comprising a holding unit.   The short circuit detection value generating means includes offset value setting means for adding a predetermined offset value to the output value of the current reference value holding means, and the offset value is changed based on the output of the current reference value holding means. The field wiring diagnosis apparatus according to claim 2, wherein   The short-circuit detection value generation means includes a filter means for inputting a read power supply voltage value of the power supply voltage and moving average, a power supply reference value holding means for updating and holding the output of the filter means, and a readback of the power supply voltage. A division means for calculating a ratio between a power supply voltage value and an output value of the power supply reference value holding means, and the read-back input to the output value of the current reference value holding means or the short-circuit diagnosis means according to the calculated ratio 4. The field wiring diagnosis apparatus according to claim 2, wherein the current value is corrected.   5. The field wiring diagnosis apparatus according to claim 2, wherein the short circuit detection value generation unit includes a limit processing unit that limits an output value of the current reference value holding unit with a predetermined value.   6. The update stopping means for stopping update processing of the current reference value holding means based on abnormality detection information from the diagnostic means or abnormality detection information of another channel. Field wiring diagnostic equipment.

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