JPH0591562A - Remote supervisory and control system - Google Patents

Abstract

PURPOSE:To provide a remote supervisory control system capable of preventing the occurrence of a trouble due to the generation of ringing and executing direct communication between a control part and a controlled part at random. CONSTITUTION:This remote supervisory and control system is provided with a detection means (consisting of a resistor r2 and a comparator (COM) 1), a holding circuit 22 for masking current detection by a current detection means only for a fixed time from the detection of a change in a current mode signal by the detection means and holding an output level for a fixed time after changing an output voltage level by detecting a change in a transmission current, and an output voltage switching means (consisting of COMs 2, 3 and TRs Q1 to Q4) for inverting the output voltage level of a power supply part or the polarity of an output voltage in accordance with the output level of the circuit 22.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a two-wire transmission line from a power source unit to which a plurality of control units and a plurality of controlled units are connected, and the power source unit is a current mode transmitted from the control unit or the controlled unit. 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 an output voltage level or a polarity of an output voltage when receiving a signal.

[0002]

2. Description of the Related Art A plurality of control parts and a plurality of controlled parts are connected to a two-wire transmission line from a power supply part, and the power supply part outputs when a current mode signal transmitted from the control part or the controlled part is received. There is known a remote monitoring control system in which a control signal is transmitted and received between a control unit and a controlled unit by changing a voltage level or a polarity of an output voltage.

[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 changed, the wiring length of the transmission line becomes long, and the wiring becomes long. Ling and C components cause ringing. Due to this ringing, the control unit or controlled unit outputs the transmission current, but the current cannot be detected or it is erroneously detected that the current is flowing even though the output of the transmission current is stopped. 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 with each other randomly. 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 transmission current transmitted from the unit changes, the current detection means for detecting the change in the transmission current and the current detection means Holding means for masking the current detection by the current detecting means for a fixed time after detecting the change of the transmission current and holding the output level for the fixed time after changing the output voltage level when detecting the change of the transmission current. And output voltage switching means for changing the output voltage level of the power supply section or the polarity of the output voltage according to the output voltage level of the holding means. To.

[0006]

When the change of the transmission current is detected by the current detection means, the current detection by the current detection means is masked for a fixed time, and when the change of the transmission current is detected, the output voltage level is changed and then the fixed time is reached. By providing the holding means for holding the output level only, the output voltage level of the power supply unit or the polarity of the output voltage is not changed by ringing.

[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 structure will be described with reference to FIG. A plurality of control units 13 and a control unit 1 are connected to the power supply unit 11 via a two-wire transmission line 12.
The controlled unit 14 controlled by 3 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 control unit 13 short-circuits and opens the two-wire transmission line 12 via the low impedance element to transmit data.

As described above, when the two-wire transmission line 12 is short-circuited in the control unit 13 via the low impedance element, a closed circuit is formed between the power supply unit 11 and the control unit 13. A transmission current flows through the power supply unit 11 and the two-wire transmission line 12
When the space is opened, a closed circuit is not formed between the power supply unit 11 and the control unit 13, so that the transmission current does not flow in the power supply unit 11. The power supply unit 11 detects the presence or absence of the transmission current, and inverts the polarity of the output voltage when the transmission current is detected or when the transmission current is not detected.

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 24 V DC power source. The anode 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 transmission 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 side 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 resistors r3 and r4 is supplied to the + terminal of the comparator COM1. This comparator COM1 is a control unit 1
3 or when the transmission current from the controlled portion 14 flows into the resistor r2, the potential of the non-grounded side terminal (point C) of the resistor r2 rises, an H level signal is output, and the transmission current stops flowing into r2. , L level signals are output.

The output of the comparator COM1 is the holding circuit 2
Entered in 2. This holding circuit 22 is a comparator COM1.
Is compared for a certain period of time T after the output level of the
The current detection by the comparator COM1 is masked, the output level is changed in response to the change in the output level of the comparator COM1, and then the output level is maintained for a certain time T or more.

The output of the holding circuit 22 is the inverter 23.
And is directly connected to the negative terminal of the comparator COM3. These comparators COM2 and COM3 have a reference voltage (5
A voltage obtained by dividing V) by resistors r5 and r6 is input as a reference voltage.

That is, 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 accordance with the output level of the holding circuit 22. .. The output of the comparator COM2 is connected to the bases of the transistors Q2 and Q4, and the output of the comparator COM3 is connected to the bases of the transistors Q1 and Q2.

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 and the transmission current flows through the resistor r2 of the power supply unit 11, the potential at the point C rises. Therefore, the output level of the comparator COM1 rises from the L level to the H level. The holding circuit 22 masks the current detection of the comparator COM1 for a fixed time T from the rising of the comparator COM1 and holds the output level at the H level for a fixed time T or more from the rising of the comparator COM1.

Therefore, for a certain period of time T, the comparator
The output of 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 is turned on and the transistor Q4 is turned 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 state, when the transmission current stops flowing,
The potential at point C becomes the ground potential. Therefore, the comparator
The output level of COM1 falls from H level to L level. The holding circuit 22 masks the current detection of the comparator COM1 for a fixed time T from the fall of the comparator COM1 and holds the output level at the L level for a predetermined time T or more after the fall of the comparator COM1.

For this reason, the comparator is operated for a fixed time T.
The output of 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. In this way, the polarity of the voltage supplied to the transmission line 12 is reversed.

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 transmission current rigs as shown in B of FIG. Therefore, the output of the comparator COM1 also changes as shown in C of FIG.
3 shows the polarity of the voltage output to the transmission line 12 as shown in E of FIG. 3 because the output level of the comparator COM1 is changed and the output level is held for a predetermined time T or more as shown in D of FIG. Is not affected by rigging. Although the power supply unit inverts the polarity of the output voltage according to the transmission current in the above embodiment, the present invention can be applied to a system in which the output level is changed.

[0024]

As described above in detail, according to the present invention, it is possible to provide a remote monitoring control system which can prevent a trouble caused by the occurrence of ringing and can directly communicate with a controlled unit at random. 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 ... 2-wire transmission line, 13 ... Control unit, 14
... Controlled part, 15 ... Lighting load.

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 the power supply unit outputs or changes an output voltage level when a transmission current transmitted from the control unit or the controlled unit changes. In a remote monitoring control system that changes the polarity of the output voltage, a current detection unit that detects a change in the transmission current, and the current detection unit for a fixed time after the change in the transmission current is detected by the current detection unit. Holding means for masking the current detection by the detecting means, detecting the change in the transmission current to change the output voltage level, and holding the output level for the fixed time or more, and the power supply according to the output level of the holding means. And an output voltage switching means for changing the output voltage level of the unit or the polarity of the output voltage.