JP2004061448A - Detection method for multi-drop wiring failure and multi-drop wiring system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily know for everybody, a failure occurrence location in a multi-drop wiring in which a plurality of signal generators are connected. <P>SOLUTION: In a multi-drop wiring system connected in parallel with the first conductor 2 and the second conductor 4 and using a plurality of signal generators 11 to 15 outputting a direct current at a constant value, connection points of the second conductor 4 and the signal generators 11 to 15 are provided for each signal generators, and these connection points are connected with anomaly detector resistors 32 to 35 with different resistances in the constitution. A monitor device 6 calculates a difference between a direct current voltage measured between the terminal of the first conductor 2 and the terminal of the second conductor 4 and the direct current voltage between the terminals in normal time. The calculated difference is used as a key to search a data base showing correspondence of the difference data and the failure location, and the found failure location is indicated. <P>COPYRIGHT: (C)2004,JPO

Description

【００３４】
表１から異常検出電圧Ｖ_ＤＥＲＲは故障箇所ごとに異なる電圧が出力され、故障箇所の識別が可能であることが分かる。また、ここで用いた各パラメータによれば、異常検出電圧Ｖ_ＤＥＲＲが故障数によって約１Ｖきざみの群をなしている。すなわち、各パラメータを所定の値とすることにより、故障数ごとに所定の電圧レベルからなるグループに分類することができる。したがって、図４に示すように、異常検出電圧Ｖ_ＤＥＲＲに適当なしきい値を設けることにより、故障数を知ることができる。ここで、故障数とはマルチドロップ配線システムに接続された信号発信器で所定の出力電流を出力していない、すなわち故障あるいは配線が断線している信号発信器の数を示す。
【００３５】
［実装例］
次に、このマルチドロップ配線システムの実装例について説明する。図５は、このマルチドロップ配線システムの実装例を示すブロック配線図である。この場合、各信号発信器（ＤＥＶ１〜ＤＥＶ５）１１〜１５が異常検出用抵抗（Ｒ２〜Ｒ５）３２〜３５を内蔵したジャンクションボックス（接続箱）８に接続され、監視装置６がジャンクションボックス８の終端部に接続されている。
【００３６】
ジャンクションボックス８は、各信号発信器１１〜１５を接続する複数の接続端子８１，８２を有する。各信号発信器１１〜１５を第１導電線２に接続する接続端子８１は内部で互いに接続されるとともに、直流電源１の＋出力と監視装置６に接続されている。各信号発信器１１〜１５を第２導電線４に接続する接続端子８２はそれぞれ抵抗値の異なる異常検出用抵抗３２〜３５で接続されている。また、異常検出用抵抗（Ｒ２）３２が接続された端部の接続端子８２は通信用抵抗（Ｒ１）３を介して直流電源１の−出力と接続され、異常検出用抵抗（Ｒ５）３５が接続された終端部の接続端子８２は監視装置６に接続されている。
【００３７】
この実装例によれば、ジャンクションボックス８の接続端子８１，８２に各信号発信器１１〜１５を接続するだけでよいため、異常検出用抵抗３２〜３５を意識せずに取付けができ、従来と比べて取付け作業に余分な時間がかかることもない。また、ジャンクションボックス８を用いるときの応用例として、ジャンクションボックス８と監視装置６を１つの筐体に一体化した構成や、ジャンクションボックス８に直流電源１の−出力と直接接続する接続端子を設け監視装置６に−出力を供給する構成などが考えられる。監視装置６に−出力を供給するようにした場合、直流電源１を監視装置６の電源として用いることができる。
【００３８】
この実施の形態によれば、複数の信号発信器が接続されたマルチドロップ配線において、障害が発生したときに監視装置６が故障箇所を表示するので、誰でも簡単に障害発生箇所を知ることができる。また、デジタル計装の中に一部アナログ的な部分を残しておくことになるので、アナログ計装からデジタル計装への移行が現場作業者にスムーズに受け入れられる効果が得られる。
【００３９】
この実施の形態では、制御ループの終端に監視装置６を接続して故障箇所を検知するようにしたが、監視装置６の機能を制御ループの終端に接続する信号発信器に内蔵させるようにしてもよい。この場合、信号発信器に監視装置と同等の異常検知機能を設けることにより、別に監視装置を設ける必要がなくなるので、省スペース化や接続工数の削減が図れる。
【００４０】
また、この実施の形態では監視装置６が測定した終端間電圧と正常時の終端間電圧の差分に基づいて故障箇所を特定する例を説明したが、式（１）の説明で記したように、あらかじめ直流電源１の出力電圧が決められており、この出力電圧が安定化されている場合は、測定した終端間電圧のみに基づいて故障箇所を特定することも可能である。この場合、図２で示した監視装置６の機能構成から演算処理部６２を除き、電圧測定部６１の出力を検索処理部６４に入力するように変更するとともに、図３で示した故障箇所ＤＢ６３の異常検出電圧を式（１）で計算した終端間電圧とすればよい。これによっても、使用できる条件が限定されるが誰でも簡単に障害発生箇所を知ることができる。
【００４１】
【発明の効果】
以上説明したように、本発明のマルチドロップ配線故障検知方法およびマルチドロップ配線システムによれば、複数の信号発信器が接続されたマルチドロップ配線において、障害が発生したときに誰でも簡単に障害発生箇所を知ることができる。
【図面の簡単な説明】
【図１】本発明に係るマルチドロップ配線システムの構成を示すブロック配線図である。
【図２】図１の監視装置の機能構成を示す機能ブロック図である。
【図３】図２の故障箇所ＤＢの構成を示す説明図である。
【図４】故障ラインごとの異常検出電圧としきい値を示すグラフである。
【図５】実施の形態に係るマルチドロップ配線システムの実装例を示すブロック配線図である。
【図６】従来のマルチドロップ配線の構成を示すブロック配線図である。
【符号の説明】
１…直流電源、２…第１導電線、３…通信用抵抗（Ｒ１）、４…第２導電線、５…ハンドヘルドコミュニケータ（ＨＣ）、６…監視装置（ＭＯＮ）、７…表示画面、８…ジャンクションボックス、１１〜１５…信号発信器（ＤＥＶ１〜ＤＥＶ５）、３２〜３５…異常検出用抵抗（Ｒ２〜Ｒ５）、６１…電圧測定部、６２…演算処理部、６３…故障箇所データベース（ＤＢ）、６４…検索処理部、６５…表示部、８１，８２…接続端子。[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a multi-drop wiring used in process control instrumentation and connecting a plurality of signal transmitters to one control loop, and more particularly to a multi-drop wiring failure detection method and a multi-drop wiring system to which the failure detection method is applied. About.
[0002]
[Prior art]
In recent years, in a signal transmitter used for process control instrumentation, digital data transmission has been used instead of the conventional 4-20 mA analog data transmission, so that a plurality of signal transmitters are provided in one control loop. It has become possible to connect multi-drop wiring. FIG. 6 is a block wiring diagram showing a configuration of a conventional multi-drop wiring, and shows an example in which five signal transmitters are connected to one control loop.
[0003]
As shown in FIG. 6, the conventional multi-drop wiring includes a DC power supply 1, a first conductive wire 2 connected to one output terminal of the DC power supply 1, and a communication power supply connected to the other output terminal of the DC power supply 1. It comprises a second conductive line 4 connected via a resistor (R1) 3 and a plurality of signal transmitters 11 to 15 connected in parallel to these conductive lines. By superimposing a predetermined alternating current signal on a constant direct current (I1 to I5) to be output, data is transmitted to a portable terminal such as a host device or a handheld communicator (HC) 5 (not shown) connected in parallel to these conductive wires. Transmitting.
[0004]
[Problems to be solved by the invention]
As described above, in the multi-drop wiring, since a plurality of signal transmitters are connected to one control loop, when a failure occurs in the control loop, there are a plurality of candidates for a fault location, and thus the fault location is specified. Failure detecting means for performing the operation is required. The conventional failure detection method for multi-drop wiring uses a host device connected to the multi-drop wiring or a mobile terminal for multi-drop wiring, such as a handheld communicator, to attempt communication with each signal transmitter, and normal communication is established. The determination was based on whether or not it could be performed.
[0005]
Therefore, only the operator who can operate the host device and the technician who can operate the handheld communicator are able to know the fault location of the multi-drop wiring, and anyone can easily find the fault location. There has been a demand for a method of detecting a failure of a multidrop wiring that can perform the method.
The present invention has been made in order to solve such a problem, and in a multi-drop wiring to which a plurality of signal transmitters are connected, a failure detection method and a failure detection method in which anyone can easily know a failure occurrence location. It is an object of the present invention to provide a multi-drop wiring system provided with a detecting means.
[0006]
[Means for Solving the Problems]
In order to solve the above-described problems, the present invention provides a DC power supply having two output terminals and outputting a predetermined DC voltage between the output terminals, and a first power supply connected to one output terminal of the DC power supply. And a second conductive line connected to the other output terminal of the DC power supply via a predetermined resistance, and a parallel connection to these conductive lines, driven by the DC power supply and having a constant DC current. And superimposing a predetermined AC signal on this DC current, a multi-drop wiring failure detection method in a multi-drop wiring system comprising a plurality of signal transmitters using these conductive lines as signal transmission lines, A connection point between the second conductive line and the signal transmitter is provided for each signal transmitter, and these connection points are connected to each other with resistors having different resistance values. End of conductive wire The DC voltage between the terminals is measured, and the measured DC voltage is used as a key to search the database showing the correspondence between the DC voltage between the terminals and the fault location in the multi-drop wiring system, and the fault corresponding to the measured DC voltage is searched. It is characterized by finding the location.
[0007]
One configuration example of this multi-drop wiring fault detection method is to measure a DC voltage between the end of a first conductive wire and the end of a second conductive wire, and then further measure the DC voltage between the DC voltage and the normal end. Calculate the difference from the DC voltage and use the calculated difference as a key to calculate the difference data between the DC voltage between the terminals at the time of occurrence of an abnormality related to the signal transmitter and the DC voltage between the terminals at the time of normal, and failure in the multi-drop wiring system. A database showing a correspondence relationship with the location is searched to find a failure location corresponding to the calculated difference.
[0008]
Also, a multi-drop wiring system according to the present invention has a DC power supply having two output terminals and outputting a predetermined DC voltage between these output terminals, and a first power supply connected to one output terminal of the DC power supply. A conductive line, a second conductive line connected to the other output terminal of the DC power supply via a predetermined resistor, and a parallel connection to these conductive lines, driven by the DC power supply and supplying a constant value of DC current. A multi-drop wiring system comprising: a plurality of signal transmitters for outputting, superimposing a predetermined AC signal on the DC current, and using these conductive lines as signal transmission lines, wherein a multi-drop wiring system is provided for each signal transmitter. And a voltage for measuring a DC voltage between a terminal of the first conductive line and a terminal of the second conductive line. Between measuring means and end A database showing the correspondence between the DC voltage and the fault location in the multi-drop wiring system, a database using the DC voltage measured by the voltage measurement means as a key, a search means for reading out the fault location, and a search means for reading out the fault location Display means for displaying the failed part.
[0009]
One configuration example of the multi-drop wiring system further includes an arithmetic unit that calculates a difference between the DC voltage measured by the voltage measuring unit and the DC voltage between the terminals at the normal time, which is measured in advance, and includes a signal transmitter. The database replaces the end-to-end DC voltage so that the difference data between the end-to-end DC voltage at the time of occurrence of the abnormality and the normal end-to-end DC voltage indicates the corresponding relationship with the fault location in this multi-drop wiring system. The searching means searches the database by using the difference calculated by the calculating means as a key instead of the DC voltage measured by the voltage measuring means, and reads out the faulty part.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below with reference to the drawings.
FIG. 1 is a block wiring diagram showing a configuration of a multi-drop wiring system according to the present invention, showing an embodiment of the present invention. In FIG. 1, this multi-drop wiring system differs from the conventional multi-drop wiring shown in FIG. 6 in that the connection between the second conductive line 4 and each signal transmitter (DEV1 to DEV5) 11 to 15 is provided. Abnormality detecting resistors (R2 to R5) 32 to 35 having different resistance values are connected to each other, and a terminal-to-terminal voltage of these conductive lines 2 and 4 is applied to a terminal of the first conductive line 2 and a terminal of the second conductive line 4. A monitoring device (MON) 6 that monitors and displays a failure location in the multi-drop wiring system on its own display screen 7 when an abnormality occurs in the signal transmitters 11 to 15 is connected.
[0011]
Here, the DC power supply 1 is a DC constant voltage power supply that drives the plurality of signal transmitters 11 to 15, and outputs a predetermined DC voltage between the + side output terminal and the − side output terminal. In the case of this embodiment, 24 V is used as the output voltage of the DC power supply 1, but the output voltage is not limited to this, and the communication resistance (R1) 3 and each abnormality detection resistance (R2 to R5) 32 to Any voltage may be used as long as the voltage obtained by subtracting the voltage drop caused by 35 falls within a voltage range in which the signal transmitters 11 to 15 can operate.
[0012]
A first conductive line 2 is connected to a + output terminal of the DC power supply 1, and a second conductive line 4 is connected to a negative output terminal via a predetermined communication resistor 3. A plurality of signal transmitters 11 to 15 are connected in parallel to the first conductive line 2 and the second conductive line 4 to form one control loop. A connection point between the second conductive wire 4 and each of the signal transmitters 11 to 15 is provided for each signal transmitter, and these connection points are connected by abnormality detection resistors 32 to 35 having different resistance values. In this case, for example, the communication resistor 3 has R1 = 250Ω, and the abnormality detection resistors 32 to 35 have R2 = 10Ω, R3 = 11Ω, R4 = 12Ω, and R5 = 13Ω.
[0013]
Each of the signal transmitters 11 to 15 is driven by the DC power supply 1 connected through the first conductive line 2 and the second conductive line 4 and outputs a constant DC current. This is a measurement control device (device) capable of digital data transmission using the conductive lines 2 and 4 as signal transmission paths by superimposing signals. Here, the DC current output from each of the signal transmitters 11 to 15 is, for example, a fixed value of 4 mA, and the AC signals to be superimposed are, for example, 1000 Hz and 2000 Hz.
[0014]
In this case, the signal transmitters 11 to 15 perform digital data transmission by setting 1000 Hz to 1 and 2000 Hz to 0. Note that the transmission method of digital data transmission is not limited to this, and any transmission method that does not affect the DC current output by the two wires may be used. Digital data transmission of each of the signal transmitters 11 to 15 is performed by a multi-drop wiring portable terminal such as a host device (not shown) or a handheld communicator (HC) 5 connected in parallel to these conductive lines 2 and 4. Is controlled.
[0015]
As shown in FIG. 2, the monitoring device 6 includes a voltage measuring unit 61, an arithmetic processing unit 62, a failure location database (hereinafter, referred to as a failure location DB) 63, a search processing unit 64, and a display unit 65. In this case, the voltage between the terminals of the conductive wires 2 and 4 is measured by the voltage measuring unit 61 and converted into numerical data as a voltage value. The voltage value converted into the numerical data is input to the arithmetic processing unit 62, the difference from the previously measured voltage value in the normal state is calculated, and the calculated difference is input to the search processing unit 64.
[0016]
As shown in FIG. 3, the failure location DB 63 is a database in which a failure line and an abnormality detection voltage are stored in association with each other. Here, the failure line indicates the failure location by the identification number of the signal transmitter. The abnormality detection voltage indicates a difference between the end-to-end voltage measured when the abnormality indicated by the failure line occurs and the normal end-to-end voltage.
[0017]
When the difference data is input from the arithmetic processing unit 62, the search processing unit 64 searches the failure location DB 63 for an abnormality detection voltage using the difference data as a key, and displays a failure location indicating a failure location corresponding to the matched abnormality detection voltage. The location information is read from the failure line field of the failure location DB 63. The read fault location information is input to the display unit 65. The display unit 65 displays the input failure location information on its own display screen 7.
[0018]
The monitoring device 6 is stored in, for example, an arithmetic processing unit such as a microcomputer, a storage unit such as a semiconductor memory, an analog input interface such as an A / D converter, a display unit such as a liquid crystal display, and a storage unit. And a computer program for realizing the functions of the monitoring device described above. Here, the analog input interface functions as the voltage measurement unit 61, and the arithmetic processing unit, the storage unit, and the computer program stored in the storage unit cooperate with each other to function as the arithmetic processing unit 62 and the search processing unit 64. The storage unit functions as the failure location DB, and the arithmetic processing unit, the storage unit, the display unit, and the computer program stored in the storage unit function together as the display unit 65.
[0019]
Next, a method of calculating data to be stored in the failure location DB 63 shown in FIG. 3 will be described. When the output voltage of the DC power source 1 and V _S, the termination voltage V _D of the conductive lines 2 and 4 monitor 6 measures is represented by the following formula (1).
[0020]
_{V D = V S -R1 × ΣI} (1~n) -R2 × ΣI (2~n) -R3 × ΣI (3~n) - ... -Rn × In ‥ (1)
[0021]
Here, R1 is the resistance value of the communication resistor, n is the number of signal transmitters, R2 to Rn are the resistance values of each abnormality detection resistor, and I1 to In are the current values output by each signal transmitter. That is, end-to-end voltage V _D becomes a value obtained by subtracting the voltage drop across the respective resistor R1~Rn from the output voltage V _S of the DC power source 1. Therefore, end-to-end voltage V _D is changed when the current in such signal generator failure or disconnection stops flowing. In this case, since each of the signal transmitters outputs a constant current, the resistance value of each of the resistors R1 to Rn is set to a different value so that the termination at the time of normal operation or when one or more signal transmitters fail. during voltage V _D becomes a different value, it is possible to identify the fault location.
[0022]
It is also possible to specify the fault location by calculating the equation (1) for the normal state and all the failure patterns and creating a database, but in this embodiment, the normal state is further calculated by the equation (2). the end-to-end voltage V _D0, calculates the difference between the end-to-end voltage V _D which can be taken for normal operation and all failure patterns, associating the difference calculated in these failure patterns as the abnormality detection voltage V _DERR, fault location DB63 To be stored.
[0023]
V _DERR = V _D −V _D0 ‥ (2)
[0024]
According to equation (2), the output voltage V _S of the DC power source 1 is canceled, the abnormality detection voltage V _DERR regardless of the supply voltage, the value determined by the failure pattern of the signal transmitter. Therefore, it is not necessary to provide data to be stored in the failure location DB 63 for each power supply voltage.
[0025]
[Calculation example]
Hereinafter, the equations (1) and (2) are applied to the case where the number of signal transmitters is five (n = 5) as an example, and the end-to-end voltage V _D of the conductive wires 2 and 4 for each fault location. And a procedure for calculating the abnormality detection voltage V _DERR . Equation (1) is expanded to equation (3) when n = 5.
[0026]
_{V D = V S - [R1} (I1 + I2 + I3 + I4 + I5) + R2 (I2 + I3 + I4 + I5) + R3 (I3 + I4 + I5) + R4 (I4 + I5) + R5 × I5] ‥ (3)
[0027]
Next, substituting the value of each parameter in equation _{(3) (V S = 24V} , I1~I5 = 4.0mA, R1 = 250Ω, R2 = 10Ω, R3 = 11Ω, R4 = 12Ω, R5 = 13Ω) , and The end-to-end voltage V _D0 when all the signal transmitters are normal is determined.
[0028]
V _D = 24− [250 × (4 + 4 + 4 + 4 + 4) + 10 × (4 + 4 + 4 + 4) + 11 × (4 + 4 + 4) + 12 × (4 + 4) + 13 × 4] /1000=18.560=V _D0 ‥ (4)
[0029]
At this time, the abnormality detection voltage V _DERR becomes V _DERR = V _D -V _D0 = 0 V from equation (2). Next, the equations (3) and (2) are calculated for every fault location. For example, the DEV1 failure or disconnection 1, the abnormality detection voltage _{V DERR} and end-to-end voltage _{V D} of when it becomes I1 = 0 are the values below equation (5) and (6).
[0030]
V _D = 24− [250 × (0 + 4 + 4 + 4 + 4) + 10 × (4 + 4 + 4 + 4) + 11 × (4 + 4 + 4) + 12 × (4 + 4) + 13 × 4] /1000=19.560 (5)
[0031]
V _DERR = 19.560-18.560 = 1.000 V ‥ (6)
[0032]
The following Table 1 shows the results of calculating the end-to-end voltage V _D and the abnormality detection voltage V _DERR for each fault location as well.
[0033]
[Table 1]

[0034]
From Table 1, it can be seen that a different voltage is output for each failure location as the abnormality detection voltage V _DERR , and that the failure location can be identified. Further, according to the parameters used here, the abnormality detection voltage V _{DERR forms} a group of about 1 V depending on the number of failures. That is, by setting each parameter to a predetermined value, it is possible to classify the number of failures into groups each having a predetermined voltage level. Therefore, as shown in FIG. 4, by _setting an appropriate threshold value for the abnormality detection voltage V _DERR , the number of faults can be known. Here, the number of failures indicates the number of signal transmitters connected to the multi-drop wiring system that do not output a predetermined output current, that is, failures or broken wiring.
[0035]
[Implementation example]
Next, an implementation example of the multi-drop wiring system will be described. FIG. 5 is a block wiring diagram showing an implementation example of the multi-drop wiring system. In this case, each of the signal transmitters (DEV1 to DEV5) 11 to 15 is connected to a junction box (connection box) 8 having built-in abnormality detection resistors (R2 to R5) 32 to 35, and the monitoring device 6 is connected to the junction box 8 Connected to termination.
[0036]
The junction box 8 has a plurality of connection terminals 81 and 82 for connecting the signal transmitters 11 to 15. The connection terminals 81 for connecting the signal transmitters 11 to 15 to the first conductive line 2 are internally connected to each other, and are also connected to the + output of the DC power supply 1 and the monitoring device 6. Connection terminals 82 for connecting the respective signal transmitters 11 to 15 to the second conductive line 4 are connected by abnormality detection resistors 32 to 35 having different resistance values, respectively. The connection terminal 82 at the end to which the abnormality detection resistor (R2) 32 is connected is connected to the negative output of the DC power supply 1 via the communication resistor (R1) 3, and the abnormality detection resistor (R5) 35 is connected. The connection terminal 82 of the connected terminal part is connected to the monitoring device 6.
[0037]
According to this mounting example, since it is only necessary to connect the signal transmitters 11 to 15 to the connection terminals 81 and 82 of the junction box 8, the mounting can be performed without being aware of the abnormality detection resistors 32 to 35. In comparison, no extra time is required for the mounting operation. In addition, as an application example when the junction box 8 is used, a configuration in which the junction box 8 and the monitoring device 6 are integrated into one housing, and a connection terminal for directly connecting the minus output of the DC power supply 1 to the junction box 8 are provided. A configuration for supplying a negative output to the monitoring device 6 is conceivable. When a negative output is supplied to the monitoring device 6, the DC power supply 1 can be used as a power source for the monitoring device 6.
[0038]
According to this embodiment, in a multi-drop wiring to which a plurality of signal transmitters are connected, when a failure occurs, the monitoring device 6 displays the failure location, so that anyone can easily know the failure location. it can. Further, since an analog part is partially left in the digital instrumentation, there is an effect that the transition from the analog instrumentation to the digital instrumentation can be smoothly accepted by the field worker.
[0039]
In this embodiment, the monitoring device 6 is connected to the end of the control loop so as to detect a failure point. However, the function of the monitoring device 6 is incorporated in a signal transmitter connected to the end of the control loop. Is also good. In this case, by providing the signal transmitter with an abnormality detection function equivalent to that of the monitoring device, it is not necessary to separately provide a monitoring device, so that space can be saved and the number of connection steps can be reduced.
[0040]
Further, in this embodiment, an example has been described in which the failure location is specified based on the difference between the end-to-end voltage measured by the monitoring device 6 and the normal end-to-end voltage. However, as described in the expression (1), If the output voltage of the DC power supply 1 is determined in advance and this output voltage is stabilized, it is also possible to specify the failure location based only on the measured end-to-end voltage. In this case, the functional configuration of the monitoring device 6 shown in FIG. 2 is changed to exclude the arithmetic processing unit 62 so that the output of the voltage measuring unit 61 is input to the search processing unit 64, and the fault location DB 63 shown in FIG. May be set to the end-to-end voltage calculated by the equation (1). This also limits the conditions that can be used, but anyone can easily know the location of the failure.
[0041]
【The invention's effect】
As described above, according to the multi-drop wiring fault detection method and the multi-drop wiring system of the present invention, when a fault occurs in a multi-drop wiring to which a plurality of signal transmitters are connected, any one can easily generate a fault. You can know the location.
[Brief description of the drawings]
FIG. 1 is a block wiring diagram showing a configuration of a multi-drop wiring system according to the present invention.
FIG. 2 is a functional block diagram illustrating a functional configuration of the monitoring device of FIG. 1;
FIG. 3 is an explanatory diagram illustrating a configuration of a failure point DB in FIG. 2;
FIG. 4 is a graph showing an abnormality detection voltage and a threshold value for each failure line.
FIG. 5 is a block wiring diagram showing a mounting example of the multi-drop wiring system according to the embodiment;
FIG. 6 is a block wiring diagram showing a configuration of a conventional multi-drop wiring.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... DC power supply, 2 ... 1st conductive wire, 3 ... Communication resistance (R1), 4 ... 2nd conductive wire, 5 ... Handheld communicator (HC), 6 ... Monitoring device (MON), 7 ... Display screen, Reference numeral 8: junction box, 11 to 15: signal transmitters (DEV1 to DEV5), 32 to 35: resistors for abnormality detection (R2 to R5), 61: voltage measurement unit, 62: arithmetic processing unit, 63: failure point database ( DB), 64: search processing unit, 65: display unit, 81, 82: connection terminals.

Claims (4)

A DC power supply having two output terminals and outputting a predetermined DC voltage between the output terminals, a first conductive line connected to one output terminal of the DC power supply, and another output of the DC power supply A second conductive line connected to the terminal via a predetermined resistance, and a second conductive line connected in parallel to these conductive lines, driven by the DC power supply and outputting a constant DC current; A multi-drop wiring failure detection method in a multi-drop wiring system including a plurality of signal transmitters that superimpose an AC signal and use these conductive lines as a signal transmission path,
A connection point between the second conductive line and the signal transmitter is provided for each of the signal transmitters, and the connection points are connected to each other with resistors having different resistance values,
A DC voltage is measured between the end of the first conductive line and the end of the second conductive line, and the measured DC voltage is used as a key, and a DC voltage between the ends and a failure in the multi-drop wiring system are measured. A multi-drop wiring fault detection method comprising: searching a database indicating a correspondence relationship with a location; and finding a failure location corresponding to the measured DC voltage. 2. The multi-drop wiring fault detecting method according to claim 1, further comprising: measuring a DC voltage between an end of the first conductive line and an end of the second conductive line, and further measuring the DC voltage and the normal state. A difference between the DC voltage between the terminals is calculated, and the difference data between the DC voltage between the terminals at the time of occurrence of an abnormality relating to the signal transmitter and the DC voltage between the terminals at the normal time is calculated using the calculated difference as a key. A database showing a correspondence relationship between the difference and a fault location in the multi-drop wiring system is searched, and a fault location corresponding to the calculated difference is obtained. A DC power supply having two output terminals and outputting a predetermined DC voltage between the output terminals, a first conductive line connected to one output terminal of the DC power supply, and another output of the DC power supply A second conductive line connected to the terminal via a predetermined resistance, and a second conductive line connected in parallel to these conductive lines, driven by the DC power supply and outputting a constant DC current; In a multi-drop wiring system comprising a plurality of signal transmitters that superimpose an AC signal and use these conductive lines as signal transmission lines,
Resistors each having a different resistance value for connecting between the second conductive line provided for each signal transmitter and a connection point of the signal transmitter,
Voltage measuring means for measuring a DC voltage between an end of the first conductive line and an end of the second conductive line,
A database indicating the correspondence between the DC voltage between the terminations and the fault location in the multi-drop wiring system,
Search means for searching the database using the DC voltage measured by the voltage measurement means as a key, and reading the fault location,
Display means for displaying the fault location read by the search means. The multi-drop wiring system according to claim 3,
Further comprising calculating means for calculating a difference between the DC voltage measured by the voltage measuring means and the DC voltage between the terminals at the normal time which has been measured in advance,
The database is
Instead of the DC voltage between the terminals, the difference data between the DC voltage between the terminals at the time of occurrence of an abnormality related to the signal transmitter and the DC voltage between the terminals at the normal time is the difference data between the DC voltage between the terminals and the failure point in the multi-drop wiring system. Are configured to show correspondence,
The search means,
A multi-drop wiring system, wherein the database is searched and the fault location is read using the difference calculated by the calculating means as a key instead of the DC voltage measured by the voltage measuring means.

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