JP3201623B2 - Line monitor terminal for remote monitoring and control system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a line monitor terminal of a remote supervisory control system for transmitting control data and supervisory data in a time division multiplex manner.

[0002]

2. Description of the Related Art Conventionally, there has been a remote monitoring control system of this type in which control data and monitoring data are transmitted by time division multiplexing as shown in FIG. That is, the central control unit 1, a plurality of monitoring terminal device 2 for monitoring the switches S ₁ to S ₄ unique address is set, the load L
₁ ~L ₄ control terminal device 3 for controlling the wireless relay terminal unit 7 are connected to an external interface terminal unit 8, and a pattern setting terminal unit 9 by a pair of signal lines 4, the central control unit 1 As shown in FIG. 3 (a), the transmission signal Vs transmitted from the terminal to the signal line 4 includes a start pulse signal ST indicating the start of signal transmission, a mode data signal MD indicating a signal mode, and terminals 2, 3, 7,. 9, an address data signal AD for transmitting 8-bit address data, and a load L
Control data signal CD for transmitting the control data for controlling the ₁ ~L _4, check sum data signal CS and the terminal device 2,
Return wait signal WT for setting a return period from 3, 7 to 9
It is a multipole (± 24 V) time division multiplexed signal, and data is transmitted by pulse width modulation. Each of the terminals 2, 3, 7 to 9 takes in control data of the transmission signal Vs when the address data of the transmission signal Vs received via the signal line 4 matches its own unique address data, and transmits the control data of the transmission signal Vs. The monitoring data signal is returned to the central controller 1 in a current mode return signal obtained by connecting an appropriate low resistance between the signal lines 4 in synchronization with the return waiting signal WT of the signal Vs. . The central control unit 1 receives an interrupt as shown in FIG. 3B returned from one of the monitoring terminal 2 or the wireless relay terminal 7, the external interface terminal 8, and the pattern setting terminal 9. When the signal Vi is received, there is provided an interrupt processing means for detecting the interrupt generation terminals 2, 7 to 9 and accessing the terminals 2, 7 to 9 to return the monitoring data. In the central control device 1, the monitoring terminal 2 or the wireless relay terminal 7, the external interface terminal 8, and the pattern setting terminal 9 are accessed as described above, and the monitoring returned to the central control device 1 is performed. Based on the data, control data to be transmitted to the control terminal 3 for controlling the corresponding loads L _{1 to} L ₄ is created, and the control data is time-division multiplexed to the control terminal 3 via the signal line 4. transmission to and controls the load L ₁ ~L _4.

A wireless relay terminal 7 is a terminal for relaying data of an optical wireless system composed of an optical wireless transmitter Y, an optical wireless receiver X and a wireless signal line 4a. The received optical signal is received by the optical wireless receiver X, the received data is received via the wireless signal line 4a, and the data is transferred to the central control device 1. Also, the external interface terminal 8 is
It is a terminal that performs data transmission with the external control device 8a, and the pattern setting terminal 9 is a terminal that transfers the pattern control data input from the data input unit 9a to the central control device 1. The main panel 6 or the distribution panel 6
a monitoring terminal 2 and a control terminal 3 disposed in a
Has a common size of a distribution board, and its control output controls a remote control relay (a latching relay that can be turned on and off by a hand switch) 5 for load control.

FIG. 4 shows an arrangement example, for example, from a central control unit 1 disposed in a main panel 6 to a monitoring and control terminal in a distribution panel 6a disposed on each floor of a building. vessels 2, 3 and interconnect the branch signal line 4 'branched from the main signal line 4, the monitoring operation switches S ₁ to S ₄ which are disposed on each floor, the control of the load L ₁ ~L ₄ both This is performed through the terminals 2 and 3 and the central control device 1.

However, in the above conventional example,
Although a large number of terminals 2 and 3 are distributed and arranged in a wide range (for example, in the distribution board 6a on each floor), the central control unit 1 detects system abnormalities such as address duplication and signal line short-circuit. Since the detection has been performed, there has been a problem that the recovery work in the event of a system abnormality becomes troublesome and the recovery of the system abnormality takes time. In other words, when a system error occurs, to detect a terminal whose address is duplicated or to detect a short-circuited portion of the signal line 4, any distribution board 6a disposed on each floor is required.
It is necessary to check whether or not a system error has occurred (by removing the terminals 2 and 3 arranged on the distribution board 6a). In such a case, there has been a problem that the time during which the entire system is down becomes longer.

The present inventors have proposed a monitor terminal as shown in FIG. This monitor terminal connects the central control device 1 with a plurality of monitoring and control terminals 2 and 3 each having a unique address set thereto through a pair of a main signal line 4 and a branch signal line 4 '. Central control unit 1 transmits transmission signal Vs for time division multiplex transmission of control data by accessing
Remote monitoring control in which monitoring data is returned from each of the terminals 2 and 3 to the central controller 1 by a current mode return signal obtained by connecting a low resistance to the signal lines 4 and 4 '. In the line monitor terminal 10 of the system, in the circuit example, the line monitor terminal 10 is inserted at a branch point of the branch signal line 4 '.

Here, the line monitor terminal 10 includes a current transformer 14 for detecting a current flowing through the branch signal line 4 ′,
An abnormality detection means including an overlap detection circuit 15a and a short-circuit detection circuit 15b for detecting a system abnormality such as address duplication or signal line short-circuit based on the output of the current transformer 14, and an operation display section 17a for displaying an abnormal state when an abnormality is detected
And an operation display means comprising a duplicate address display section 17b, and a switch means comprising a disconnection relay 19 having a relay contact 19a inserted in series with the signal line 4 'and turned off when a signal line short circuit is detected.

In the illustrated example, the signal line short-circuit state is eliminated.
The transmission signal Vs is received and the circuit power is supplied.
Automatic return means that automatically turns on the switch means when
(Soft). Here, the transmission signal reception
The circuit 12 converts the transmission signal Vs into a diode D₁Rectification at
And Zener diode ZD₁At TTL level signal
And output. The power supply circuit 13 outputs the transmission signal Vs
Capacitor C rectified by diode bridge DB ₁To
And smooth, Zener diode ZD_TwoAnd Transis
TA Q₁The constant voltage obtained by
Supply. Duplication detection circuit 15a and short circuit detection circuit 15
b is the comparator CP₁, CP_TwoFormed by the signal
The output of the current transformer 14 for detecting the current flowing through the line 4 'is
When the voltage exceeds the preset reference voltage,
An overlap detection signal and a short-circuit detection signal are output. Operation display 1
7a is a signal indicating that the transmission signal Vs is being received.
A light emitting diode (LDa) for displaying address duplication;
Light emitting diode for indicating short circuit of signal line with LD LDb
And the transistor Qc._Four~ Q₆More
The lighting control is performed by the drive circuit 16. Duplicate ad
Display part 17b is formed by a two-digit number display LED.
And a drive circuit 16b composed of a drive IC.
Driven. Latching relay 19 is set winding L
_SAnd reset winding L_R-Winding latching equipped with
Formed by a relay, the transistor Q_Two, Q_ThreeConsists of
Driven by the drive circuit 18. The arithmetic processing circuit 11
Formed using a microcomputer and received
Transmission signal Vs, duplicate detection circuit 15a, short circuit detection circuit
15b based on each detection signal output from the
And display of duplicate addresses
The relay 19 is controlled. Switch times
The path 20 includes a reset switch SWb and a recovery switch SW
c, formed by the display switch SWd. Also, 1
1a: Runaway of microcomputer of arithmetic processing circuit 11
Watchdog that automatically resets when
I'm imma.

Hereinafter, the operation of the circuit example of FIG. 5 will be described. Now, the terminals 2 and 3 are sequentially and cyclically accessed by the transmission signal Vs transmitted from the central controller 1 via the signal lines 4 and 4 ', and the monitoring data (switch The state monitoring data and the load operation confirmation data) are returned by a return signal including a current mode signal. This current mode signal is a signal obtained by connecting a low resistance between the signal lines 4 'during the return period set by the return standby signal WT. When the low resistance is connected, the signal lines 4 and 4' The current flowing through increases. Therefore, the central controller 1 detects a current increase in the return period of the current flowing through the signal line 4 and receives the return signal.

Here, if an address duplication in which the same unique address is set in the plurality of terminals 2 and 3 occurs, the plurality of terminals 2 and 3 are accessed simultaneously, and during the same return period, Since the low resistance is connected to the plurality of terminals 2 and 3, the amount of increase in the current flowing through the branch signal line 4 'is multiplied by a plurality (for example, when the unique addresses of the two terminals 2 and 3 are the same). Is doubled). Therefore, the duplication detection circuit 15a of the line monitor terminal 10 detects an address duplication by checking whether the current flowing through the branch signal line 4 'during the return period is twice or more the normal current mode signal.

On the other hand, when a short circuit occurs in the branch signal line 4 ', the current flowing through the branch signal line 4' is much larger than a normal current. '' Current transformer 14 that detects the current flowing through
Short-circuit detection is performed based on whether the output is equal to or higher than a preset short-circuit detection reference voltage. Here, in the illustrated example, the signal line short-circuit can be reliably determined by the processing flow as shown in FIG. 6, and the burden is not placed on the arithmetic processing circuit 11 composed of a microcomputer. That is, in order to reliably detect a short circuit, it is necessary to constantly check whether or not there is a short circuit. In this case, the arithmetic processing circuit 11 cannot perform other arithmetic processing. Checking. However, it is not appropriate when the response speed becomes a problem or when it is desired to prevent malfunction due to noise.

Therefore, in the illustrated example, in a normal case where no signal line short circuit has occurred, it is checked whether or not the sign of the transmission signal Vs transmitted via the signal line 4 'is always inverted. The current is checked to reliably determine a signal line short circuit. FIG.
When a short-circuit current flows as shown in FIG. 7A, a pulse signal (pulse width t) as shown in FIG. 7B is output as a detection signal output from the short-circuit detection circuit 15b.

Here, the arithmetic processing circuit 11 transmits the transmission signal V
It is checked whether or not there is a signal stop of s. If there is no signal stop, other arithmetic processing other than the short circuit detection is performed. On the other hand, if a signal line short circuit occurs, the transmission signal Vs cannot be detected. Therefore, first, a 10 ms timer is set, and “3” is set in the counter. Next, a timer checks whether or not the short-circuit detection signal output from the short-circuit detection circuit 15b has been stopped for 10 ms or more. If it is determined that the short-circuit has been detected, "1" is subtracted from the counter value. When the counter value becomes "0" by repeatedly performing the above, it is determined that a short circuit has occurred. Next, when it is determined that the signal line is short-circuited, the disconnection relay 19 is driven to turn off the relay contact 19 a, and the branch signal line 4 ′ farther than the line monitor terminal 10 is disconnected from the main signal line 4. Therefore, the terminals 2, 3 connected to the disconnected branch signal line 4 '
Does not operate, but the terminals 2 and 3 connected to the other branch signal lines 4 'operate normally and the whole system does not go down.

Since the determination of the signal line short-circuit in the central control unit 1 is made based on whether or not the short-circuit current is continuously obtained for 100 ms or more, the determination of the signal line short-circuit in the line monitor terminal 10 is made in 60 ms. In this way, before the short-circuit detection process of the central control unit 1 is performed, the line monitor terminal 10 disconnects the farther branch signal line 4 ′ so that the entire system does not go down.

In a state where the signal line short-circuit processing (relay contact 19a is turned off) is performed, the central control device 1 is temporarily stopped.
When the power supply is turned off, the signal line short circuit is released, and the power supply is turned on again, the line monitor terminal 10 transmits the transmission signal Vs
Is received and the circuit power is supplied. When the power is turned on, the disconnecting relay 19 is reset, the relay contact 19a is turned on, and the branch signal line 4 ′ is connected to the main signal line 4 ′.
Automatically connected to the system, and the entire system returns to a normal operation state. Therefore, the reset operation at the time of occurrence of the signal line short circuit becomes unnecessary, and the operation becomes easy.

[0016]

However, when constructing a system and connecting a plurality of terminals while constructing a live line, a large inrush current may flow. Due to this inrush current, the line monitor terminal 10 may erroneously determine that the current is a short-circuit current.

SUMMARY OF THE INVENTION The present invention has been made in view of such problems, and an object of the present invention is to provide a line monitor terminal of a remote monitoring control system which does not erroneously determine an inrush current as a short circuit current. It is in.

[0018]

According to the present invention, in order to achieve the above-mentioned object, a central control unit is connected to a plurality of monitoring and control terminals having unique addresses by a pair of signal lines. The central control unit sends out a transmission signal for time division multiplexing transmission of control data by accessing each terminal device, and monitors each terminal with a current mode return signal obtained by connecting a low resistance to a signal line. A line monitor terminal of a remote monitoring and control system adapted to return a signal from a device to a central control device, wherein the current transformer detects a current flowing through a signal line, and a short circuit detection detects a signal line short circuit based on a current transformer output. Means, operation display means for displaying a short-circuit state when a short-circuit is detected, and switch means which is inserted in series with the signal line and is turned off when the signal line short-circuit is detected,
The maximum value at which the signal voltage drops due to the inrush current is set in advance as a reference voltage, and this reference voltage is compared with the signal voltage.
If the signal voltage does not fall below the reference voltage,
Inrush current monitoring means for preventing the output means from starting short circuit detection is provided.

[0019]

According to the line monitor terminal of the remote monitoring and control system of the present invention, when an inrush current flows during construction work in a live state, the signal voltage of the signal line does not decrease unlike a short circuit accident. When the signal voltage drop does not fall below the predetermined reference voltage, the inrush current monitoring means does not start the short-circuit detection of the short- circuit detection means. Therefore, the short circuit detecting means does not erroneously detect a short circuit due to the rush current.

[0020]

The present invention will be described below with reference to examples. FIG. 1 shows a circuit of a line monitor terminal 10 of the present invention,
Circuits and elements having the same numbers and symbols as those of the circuit and elements of FIG. 5 have the same configuration and operation, and the main points different from the line monitor terminal 10 of FIG. 5 are as follows.

First, the difference is that the display at the time of the overlap detection is lit by the two-color light emitting diodes LEDb ₁ and LEDb ₂ , and Q ₅₁ and Q ₅₂ are driving transistors. In addition, the short-circuit detection is different from the output of the current transformer 14 by monitoring whether or not the signal voltage has become substantially zero, and when any of the detections is present, it is determined that the short-circuit is detected.
It is the comparator circuit 21 that performs this signal voltage detection.

Further, the difference is that a means for monitoring an inrush current, which is a main component of the present invention, is added. The comparator circuit 22 as the inrush current monitoring means has a maximum reduction in signal voltage when an inrush current flows. Assuming the voltage at the time, the resistance R
Using the voltage divided by a and Rb as a reference voltage, the reference voltage is compared with the signal voltage divided by the resistors Rc and Rd, and the comparison output is input to the arithmetic processing circuit 11 to the inrush current detection port. The arithmetic processing circuit 11 does not start the short circuit detection while the comparator circuit 22 detects the inrush current.

Therefore, it is possible to prevent the output of the current transformer 14 from judging a short circuit, and to prevent the erroneous judgment of a short circuit when an inrush current is flowing and short circuit processing.

[0024]

According to the present invention, in the line monitor terminal configured as described above, the maximum value at which the signal voltage drops due to the inrush current is set in advance as the reference voltage, and the signal voltage does not drop below this reference voltage. Then, since the inrush current monitoring means for delaying the detection start of the short-circuit detection means is provided, even if an inrush current flows when the construction work is performed in a live state, the inrush current monitoring means may detect the short-circuit detection means. There is an effect that the detection operation is not started and the rush current can be prevented from being erroneously detected as a short circuit by the short circuit detection unit.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing one embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of a remote monitoring control system according to the present invention.

FIG. 3 is an operation explanatory diagram of the system of FIG. 2;

FIG. 4 is a diagram illustrating the arrangement of the system of FIG. 2;

FIG. 5 is a conventional line monitor terminal.

FIG. 6 is a flowchart for explaining the operation of FIG. 5;

FIG. 7 is an operation explanatory diagram of a conventional example.

[Description of Signs] 11 Arithmetic processing circuit 14 Current transformer 22 Comparator circuit

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q 9/00-9/16 H03J 9/00-9/06

Claims (1)

(57) [Claims] 1. A central control unit is connected to a plurality of monitoring and control terminals to which a unique address is set via a pair of signal lines, and each terminal is accessed to transmit control data in a time-division multiplex manner. While transmitting the transmission signal from the central controller,
A line monitor terminal of a remote monitoring and control system configured to return monitoring data from each terminal to a central control device with a current mode return signal obtained by connecting a low resistance to a signal line, A current transformer for detecting a flowing current, a short-circuit detecting means for detecting a signal line short-circuit based on a current transformer output, an operation display means for displaying a short-circuit state when a short-circuit is detected, and a series-inserted signal line for detecting a signal line short-circuit A switch means to be turned off is provided, and a maximum value at which a signal voltage drops due to an inrush current is set in advance as a reference voltage, and the signal is compared by comparing the reference voltage with the signal voltage.
If the signal voltage does not fall below the reference voltage,
A line monitor terminal for a remote monitoring and control system, characterized by comprising an inrush current monitoring means that does not start short-circuit detection by a stage .