JPH0630475A - Remote supervisory and control system - Google Patents

Abstract

PURPOSE:To prevent the generation of a trouble due to the generation of ringing by setting up a period for masking the detection of a change by a current detecting means during the period of specific set time in accordance with the changed state of a return current. CONSTITUTION:Time to be required from the setting of a J-KFF 23 up to its reset is set up in set time T1. When the flow of a return current is interrupted under the status, the potential of a point C is turned to ground potential. Thereby the output of a comparator COM1 is raised to an 'H' level. Synchronously with the rise of the output, a change detecting circuit 22 outputs a trigger signal to the J terminal of the F-KFF 23. Thereby the Q output of the FF 23 is turned to the 'H' level and the Q output of a D-FF 26 is turned to an 'L' level. Time to be required from the setting of the FF 23 up to its reset is set up in set time T2. Thereby even when the polarity of voltage of a transmission line 12 is inverted, the output of the comparator COM1 is set up to the changed level time T1 or T2 and the influence of ringing is not generated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention has a plurality of control units and a plurality of controlled units connected to a two-wire transmission line from a power supply unit, and the power supply unit receives a return current returned from the control unit or the controlled unit. Then, the present invention relates to a remote monitoring control system in which a control signal is transmitted and received between a control unit and a controlled unit by changing the output voltage level or the polarity of the output voltage.

[0002]

2. Description of the Related Art A plurality of control units and a plurality of controlled units are connected to a two-wire transmission line from a power supply unit, and when the power supply unit receives a return current returned from the control unit or the controlled unit, the output voltage level or By changing the polarity of the output voltage,
A remote monitoring control system is known in which a control signal is transmitted and received between a control unit and a controlled unit.

[0003]

However, in the conventional remote monitoring and control system, when the output voltage level of the power supply section or the polarity of the output voltage is reversed, the wiring length of the transmission line becomes longer, which leads to the wiring. Ringing occurs due to the L and C components of. Due to the occurrence of this ringing, the control unit or controlled unit outputs the return current, but the current cannot be detected, or the output of the return current is stopped and the current is erroneously detected as flowing. There was a problem to do.

The present invention has been made in view of the above points, and an object thereof is to provide a remote monitoring control system capable of preventing a defect due to the occurrence of the ringing and allowing the control section and the controlled section to directly communicate at random. To provide.

[0005]

In a remote monitoring control system according to the present invention, a plurality of control units and a plurality of controlled units are connected to a two-wire transmission line from a power supply unit, and the power supply unit is a control unit or a controlled unit. In a remote monitoring control system in which the output voltage level or the polarity of the output voltage is changed when the return current returned from the unit is received, current detection means for detecting the change in the return current and detection by the current detection means A state in which the return current has a period for masking the detection of the change by the detection unit according to the change state of the return current detected by the current detection unit The time for masking the detection of the change in the return current is set to the first when the change to the non-existence state and the case where the change to the non-existence state occurs. Time setting section or a second setting time that can be switched and set, holding means for holding the detection output of the current detecting means during the first setting time and the second setting time, and this holding And means for changing the output voltage level of the power supply unit or the polarity of the output voltage according to the output level of the means.

[0006]

With the change period of the return current depending on the change state of the return current, the period of masking the detection of the change by the current detecting means changes depending on the change of the return current depending on whether there is a return current or not. The detection is masked only during the first set time or the second set time.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A remote monitoring control system according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is an overall configuration diagram of a remote monitoring control system, FIG. 2 is a diagram showing a detailed configuration of a power supply unit, and FIG. 3 is a timing diagram for explaining the operation.

In FIG. 1, reference numeral 11 is a power supply unit whose detailed configuration is described with reference to FIG. A plurality of control units 13 and control unit 1 are connected to the power supply unit 11 via a two-wire transmission line 12.
The controlled unit 14 controlled by 2 is connected.

The control unit 13 is provided with a switch SW,
For example, a lighting load 15 that is on / off controlled by a switch SW is connected to the controlled unit 14.
Commercial power is supplied to these lighting loads 15.

The control unit 13 is mainly composed of, for example, a microcomputer, and has a memory for storing the address of the illumination load controlled by the switch SW of the control unit 13. When the switch SW is turned on, the two-wire transmission line 12 is short-circuited in the control unit 13 via the low impedance element.

As described above, when the two-wire transmission line 12 is short-circuited in the control unit 12 via the low impedance element, a closed circuit is formed between the power supply unit 11 and the control unit 13, When the return current flows through the power supply unit 11 and the switch SW is turned off, a closed circuit is not formed between the power supply unit 11 and the control unit 13, and thus the return current does not flow through the power supply unit 11. As described above, by sending the return current intermittently, the address of the control unit 13 to be controlled, its own address, the lighting control signal (for example, ON / OFF signal), etc. are transmitted in the current mode. The power supply unit 11 detects the presence of the return current, detects the presence of the return current, and inverts the polarity of the output voltage accordingly.

Next, the detailed structure of the power supply unit 11 will be described with reference to FIG. In FIG. 2, reference numeral 21 is, for example, a DC power supply of 24V. The curve of the DC power source 21 is grounded via a resistor r1 and a Zener diode ZD1.
A reference voltage of 5V is taken out from the non-grounded side terminal of the Zener diode ZD1.

Further, the DC power supply 21 is connected to the collectors of npn type transistors Q1 and Q2. The emitters of the transistors Q1 and Q2 are connected to the emitters of pnp type transistors Q3 and Q4, respectively. Transistor Q
The collectors of 3 and Q4 are connected to each other and then grounded via a resistor r2 for detecting a return current.

The connection point A between the emitter of the transistor Q1 and the emitter of Q3 and the connection point B between the emitter of the transistor Q2 and the emitter of transistor Q4 are the two-wire transmission line 1
Connected to 2.

The non-grounded terminal of the resistor r2 is a comparator CO.
Connected to the-terminal of M1. A voltage obtained by dividing the reference voltage (5V) by the resistors r3 and r4 is supplied to the + terminal of the comparator COM1. This comparator COM1 is a control unit 1
2 or when the return current from the controlled part 13 flows into the resistor r2, the potential of the non-grounded side terminal (point C) of the resistor r2 rises, an L level signal is output, and the return current stops flowing into r2. , H level signal is output.

The output of this comparator COM1 is a comparator.
The output of the comparator COM1 detects a change between the H level and the L level and is input to the change detection circuit 22 which outputs a trigger signal. The trigger signal output from the change detection circuit 22 is input to the J terminal of the JK flip-flop 23. The clock output from the clock generation circuit 24 is input to the clock terminal of the JK flip-flop 23.

The clock output from the clock generation circuit 24 is also output to the counter 25. The counter 25 starts counting after the enable terminal ET becomes the H level, and when the count value counts a count value preset as a load value, the carry terminal CR
Outputs a carry signal to the K terminal of the JK flip-flop 23.

The Q output of the JK flip-flop 23 is input to the clock terminal of the D-type flip-flop 26. The number 1 output of the D-type flip-flop 26 is connected to the D input, and its Q output is connected to the-terminal of the comparator COM2 via the inverter 27 and directly to the-terminal of the comparator COM3. Connected to the terminal. To the + terminals of these comparators COM2 and COM3, a voltage obtained by dividing the reference voltage (5V) by the resistors r5 and r6 is input as the reference voltage.

[0019]

[Equation 1]

That is, the COM2 and COM3 are constructed so that an H level signal is output from one of the comparators and an L level signal is output from the other comparator in response to the Q output of the flip-flop 26. . Comparator COM2
Is connected to the bases of transistors Q2 and Q4, and the output of comparator COM3 is connected to transistors Q1 and Q4.
It is connected to two bases.

Next, the operation of the embodiment of the present invention constructed as above will be described. When the switch SW of the control unit 13 is turned on, the control unit 13 starts transmitting the current mode signal. As a result, when the return current flows through the resistor r3 of the power supply unit 11, the potential at the point C rises. Therefore, the output level of the comparator COM1 falls from H level to L level. Then, the change detection circuit sends the trigger signal to the JK flip-flop 23 of the J in synchronization with this fall.
Output to the terminal. As a result, the Q output of the JK flip-flop 23 changes to the H level, and the Q output of the D-type flip-flop 26 is inverted and becomes the H level.

Therefore, the output of the comparator COM2 becomes L level and the output of the comparator COM3 becomes H level. When the output level of COM2 becomes L level, the transistor Q2 turns off and the transistor Q4 turns on. When the output level of COM3 becomes H level, the transistor Q1 is turned on and the transistor Q3 is turned off. Therefore, 24V is supplied to the point A.

By the way, the counting operation of the counter 25 is started after the Q output of the JK flip-flop 23 becomes H level, and when the count value preset as the load value is reached, the carry from the counter 25 is carried out. A signal is output to the K terminal of the JK flip-flop 23, and J
The Q output of the K flip-flop 23 returns to the L level.
That is, the D-type flip-flop 26 cannot be inverted even if the trigger signal is input from the change detection circuit 22 before the JK flip-flop 23 is set and reset. The time from when the JK flip-flop 23 is set to when it is reset is the counter 2
It is determined by the load value of 5 and is set to the set time T1 here.

In this state, if the return current stops flowing,
The potential at point C becomes the ground potential. Therefore, the comparator
The output level of COM1 rises from L level to H level. Then, the change detection circuit outputs a trigger signal to the J terminal of the JK flip-flop 23 in synchronization with this rising edge. As a result, the Q output of the JK flip-flop 23 changes to the H level and the Q output of the D-type flip-flop 26.
The output is inverted and becomes L level.

Therefore, the output of the comparator COM2 becomes H level and the output of the comparator COM3 becomes L level. When the output level of COM2 becomes H level, the transistor Q2 turns on and the transistor Q4 turns off. Further, when the output level of COM3 becomes L level, the transistor Q1 turns off and the transistor Q3 turns on. Therefore, 24V is supplied to the point B. In this way, the polarity of the voltage supplied to the transmission line 12 is reversed.

By the way, when the count output of the counter 25 is started after the Q output of the JK flip-flop 23 becomes H level and the count value preset as the load value is reached, the carry from the counter 25 is carried out. A signal is output to the K terminal of the JK flip-flop 23, and J
The Q output of the K flip-flop 23 returns to the L level.
That is, the D-type flip-flop 26 cannot be inverted even if the trigger signal is input from the change detection circuit 22 before the JK flip-flop 23 is set and reset. The time from when the JK flip-flop 23 is set to when it is reset is the counter 2
It is determined by the load value of 5 and is set to the set time T2 here.

When the polarity of the voltage supplied to the transmission line 12 is reversed, ringing occurs as shown in A of FIG. 3 due to the L and C components of the wiring due to the increase in the wiring length of the transmission line 12. To do. Therefore, the return current rigs as shown in B of FIG. Therefore, the output of the comparator COM1 also changes as shown in C of FIG.
Set the output of COM1 to the level after change for the set time T1 or T
Since only 2 is held, the polarity of the voltage appearing on the transmission line 12 is not affected by rigging as shown in E of FIG.

[0028]

As described above in detail, according to the present invention, it is possible to provide a remote monitoring control system capable of preventing a trouble caused by the occurrence of ringing and allowing the control section and the controlled section to directly communicate with each other randomly. it can.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a remote monitoring control system.

FIG. 2 is a diagram showing a detailed configuration of a power supply unit.

FIG. 3 is a timing chart for explaining the operation.

[Explanation of symbols]

11 ... Power supply unit, 12 ... Two-wire transmission line, 13 ... Control unit, 14
... Controlled part, 15 ... Lighting load.

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[Procedure amendment]

[Submission date] September 1, 1993

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

[Figure 1]

[Fig. 2]

[Figure 3]

Claims (1)

[Claims] 1. A plurality of control units and a plurality of controlled units are connected to a two-wire transmission line from a power supply unit, and when the power supply unit receives a return current returned from the control unit or the controlled unit, the output voltage level or In a remote monitoring control system in which the polarity of the output voltage is changed, a current detection means for detecting a change in the return current and a trigger signal is generated at the timing when the return current detected by the current detection means changes. The period for masking the detection of the change by the detection means depending on the change state of the return current detected by the trigger generation means and the current detection means is changed from the state with the return current to the state without the return current and the state without the return current. The time for masking the detection of the change in the return current depending on the change is set as the first set time or the second set time. Possible clock measuring section, holding means for holding the detection output of the current detecting means during the first set time and the second set time, and the output voltage level of the power supply section according to the output level of the holding means. Alternatively, the remote monitoring and control system is provided with means for changing the polarity of the output voltage.