JP3156309B2 - Signal transmission method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply unit in which a plurality of control units and a plurality of controlled units are connected to a transmission line from a power supply unit, and the power supply unit receives a current mode signal transmitted from the control unit or the controlled unit. The present invention relates to a signal transmission method in a remote monitoring and control system in which the polarity of an output voltage is changed upon reception to transmit and receive a control signal between a control unit and a controlled unit.

[0002]

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

[0003]

However, in the conventional remote monitoring and control system, when the output voltage of the power supply unit is inverted when the polarity of the output voltage of the power supply unit is changed, the output voltage becomes zero potential. As a result, the transmission current becomes zero, so that the output voltage of the power supply unit is controlled to return to the original polarity. Therefore, there is a problem that the output voltage of the power supply voltage oscillates.

The present invention has been made in view of the above points, and has as its object the purpose of connecting a plurality of control units and a plurality of controlled units to a transmission line from a power supply unit, wherein the power supply unit is a control unit or a controlled unit. In a remote monitoring and control system in which the polarity of an output voltage is changed when a current mode signal transmitted from the control unit is received to transmit and receive a control signal between a control unit and a controlled unit, It is an object of the present invention to provide a signal transmission method capable of preventing oscillation of a voltage output from a device.

[0005]

According to a first aspect of the present invention, there is provided a signal transmission system comprising: a two-wire transmission line; a bipolar voltage output means for outputting a bipolar voltage signal to the two-wire transmission line; Designation means for designating the polarity of the bipolar voltage signal output from the voltage output means by an output level; current change detection means for detecting a change in current flowing through the transmission line; and a change in current by the current change detection means. Means for inverting the output level of the designating means when detected, and for prohibiting switching of the designating means for a fixed time thereafter.

According to a second aspect of the present invention, there is provided a signal transmission system, comprising: a two-wire transmission line; a multi-pole voltage output means for outputting a multi-pole voltage signal to the two-wire transmission line; Designating means for designating the polarity of the bipolar voltage signal by an output level, voltage detecting means for detecting a voltage supplied to the two-wire transmission line, and current detecting means for detecting a current flowing through the two-wire transmission line. , The voltage detected by the voltage detecting means
And that the current detected by the current detecting means is zero.
Switching means for holding the output level of the designation means and switching the output level of the designation means based on the voltage detected by the voltage detection means and the current detected by the current detection means. It is characterized by the following.

[0007]

According to the first aspect, when a change in the current is detected by the current change detecting means, the output level of the specifying means is inverted, and thereafter, the switching of the specifying means is prohibited for a certain period of time.

[0008] In the second aspect, the voltage and current of the transmission line are detected, and when the detected voltage and current are zero.
Keeps the output level of the designation means and detects
The output level of the power supply section is switched according to the voltage and the current .

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A signal transmission system according to a first embodiment of the present invention will be described below with reference to the drawings. 1 is a schematic 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 circuit diagram showing a detailed configuration of a controlled unit, and FIG. 4 is a detailed configuration of a control unit. FIG. 5 is a diagram showing the format of transmission data transmitted via a transmission line;
FIG. 6 is a diagram illustrating a voltage and a transmission current output from the power supply unit to the transmission line.

In FIG. 1, reference numeral 11 denotes a power supply unit for explaining a detailed configuration thereof with reference to FIG. The power supply unit 11 has a plurality of control units 13 and control units 1 via a two-wire transmission line 12.
3 is connected to the controlled unit 14 controlled by the control unit 3.

The control unit 13 is provided with a switch SW1, and the controlled unit 14 is connected to, for example, an illumination load 141 that is turned on / off by the switch SW. Commercial power is supplied to these lighting loads 141.

The control unit 13 is constructed mainly of a microcomputer, for example, and has a memory for storing the address of the lighting load controlled by the switch SW1 of the control unit 13. When the switch SW1 is turned on, the two-wire transmission line 12 is short-circuited and opened via the low impedance element in the control unit 13 to transmit data.

As described above, when the two-wire transmission line 12 is short-circuited through the low impedance element in the control unit 13, 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 gap 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 through the power supply unit 11.

The power supply unit 11 detects the presence or absence of the transmission current, and reverses the polarity of the output voltage when the transmission current is detected or when the transmission current is no longer detected.

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

Further, the anode of the DC power supply 21 is connected to the collectors of the npn transistors Q1 and Q2. The emitters of the transistors Q1 and Q2 are pnp type transistors Q
3 and Q4, respectively.

After the collectors of the transistors Q3 and Q4 are connected to each other, they are grounded via a transmission current detecting resistor r2.

A connection point A between the emitter of the transistor Q1 and the emitter of Q3 and a connection point B between the emitter of the transistor Q2 and the emitter of the transistor Q4 are two-wire transmission lines 1.
2 are connected.

The non-ground side terminal of the resistor r2 is a comparator CO.
Connected to the negative terminal of M1. The + terminal of the comparator COM1 is supplied with a voltage obtained by dividing the reference voltage (5 V) by the resistors r3 and r4. This comparator COM1 is the control unit 1.
3 or the transmission current from the controlled end 14 flows into the resistor r2, the potential of the non-ground side terminal (point C) of the resistor r2 rises, an L level signal is output, and the transmission current stops flowing into r2. Output an H level signal.

The output of the comparator COM1 is input to the B terminal of the one-shot circuit 22 and the AND circuit 23
Is input to one of the input terminals. The one-shot circuit 22 outputs an L level signal from its Q output for a predetermined time T after the output of the comparator COM1 falls from H level to L level. This Q output is input to the other input terminal of the AND circuit 23.

The output of the AND circuit 23 is connected to the negative terminal of a comparator COM2 via an inverter 24.
Connected directly to negative terminal of comparator COM3. A voltage obtained by dividing the reference voltage (5 V) by the resistors r5 and r6 is input to the + terminals of the comparators COM2 and COM3 as the reference voltage.

That is, the comparators COM2 and COM3 are configured so that one comparator outputs an H level signal and the other comparator outputs an L level signal in accordance with the output level of the AND circuit 23. .

The output of the comparator COM2 is a transistor Q
The output of comparator COM3 is connected to the bases of transistors Q1 and Q2.

Next, a detailed configuration of the controlled unit 14 will be described with reference to FIG. The controlled unit 14 is an on / off terminal for controlling the lighting load 141 connected thereto to be turned on / off. In FIG. 3, p1 and p2 are transmission terminals for connecting to the transmission line 12. This transmission terminal p
The input terminals of the diode bridge DB1 are connected to both ends of 1 and p2. Further, the transmission terminal p2 is grounded via a resistor r11 and a Zener diode ZD2, and the potential at the connection point between the resistor r11 and the Zener diode ZD2 is input to the processing unit 31 as a reception signal RD. Diode bridge D
The output terminal of B1 is connected via a resistor r12 to the collector of transistor Q11, whose emitter is grounded. The return signal SD output from the processing unit 31 is input to the base of the transistor Q11 via the resistor r13.

Further, a smoothing circuit 32 is connected to the diode bridge DB1, and this smoothing circuit 32
2 is rectified and smoothed to generate a voltage of 5 V, which is supplied to the processing unit 31 and the like.

The processing section 31 is mainly composed of a microcomputer, and reads a destination address from transmission data (having a transmission format shown in FIG. 5) received as a reception signal RD. The other party's address is compared with the address of the controlled unit 14 stored in the storage means (not shown), and if they match, control is performed to fetch all transmission data. Then, processing corresponding to the control data, for example, the relay coil RY1 or RY2 is selectively excited to control the lighting load 141 to turn on and off.

The output terminal Do of the processing unit 31 is connected to a resistor r.
14 is connected to the base of the transistor Q12. The emitter of this transistor Q12 is grounded. The collector of this transistor Q12 is a set relay coil RY.
1 is connected to one end.

The output terminal D1 of the processing section 31 is connected to a resistor r.
15 is connected to the base of the transistor Q13. The emitter of this transistor Q13 is grounded. The collector of this transistor Q13 is a relay coil R for resetting.
Connected to one end of Y2.

The output terminal of the diode bridge DB1 is connected to the other ends of the relay coils RY1 and RY2 via a smoothing circuit composed of a diode and a capacitor.

A relay switch S1 is closed when the relay coil RY1 is excited, and is opened when the relay coil RY2 is excited. This relay switch S
Lighting loads 141 are connected to both ends of the light source 1.

Next, a detailed configuration of the control unit 13 will be described with reference to FIG. In FIG. 4, p3 and p4 are transmission terminals for connecting to the transmission line 12. This transmission terminal
The input terminals of the diode bridge DB2 are connected to both ends of p3 and p4. Further, the transmission terminal p4 is grounded via a resistor r21 and a Zener diode ZD3, and the potential at the connection point between the resistor r21 and the Zener diode ZD3 is input to the processing unit 41 as a reception signal RD. Diode bridge D
The output terminal of B2 is connected via a resistor r22 to the collector of a transistor Q21, whose emitter is grounded. The transmission signal SD output from the processing section 41 is input to the base of the transistor Q21 via the resistor r23.

Further, a smoothing circuit 42 is connected to the diode bridge DB2.
2 is rectified and smoothed to generate a voltage of 5 V and supplied to the processing unit 41 and the like.

The processing section 41 is mainly composed of a microcomputer, and reads a destination address from transmission data (having a transmission format shown in FIG. 5) received as a reception signal RD. The other party address is compared with the address of the control unit 13 stored in the storage means (not shown), and if they match, control is performed to fetch all the transmission data. When the switch SW1 is operated, the transmission signal SD is output in the transmission format shown in FIG.

The potential at the connection point between the switch SW1 and the resistor r24 is input to the input terminal Io of the processing section 41.
One end of the resistor r24 is grounded.

Further, the output terminal Do of the processing section 41 is connected to the base of the transistor Q22. The emitter of this transistor Q22 is grounded. The collector of the transistor Q22 is connected to the resistor r25 via the light emitting element 43.
To one end.

The output terminal of the diode bridge DB2 is connected to one end of a resistor r25 via a smoothing circuit composed of a diode and a capacitor.

Next, the transmission format of a signal transmitted through the transmission line 12 will be described with reference to FIG.
In this transmission format, the "start" signal is followed by the "self address", "other party address", "control code", and "AC".
K "signal.

Next, the operation of the first embodiment of the present invention configured as described above will be described. When no transmission current flows through the power supply unit 11, the potential of the non-ground terminal (point C) of the resistor r2 is the ground potential. Therefore, the output of the comparator COM1 is at the H level. Further, since the output of the one-shot circuit 22 is at the H level in the normal state, the output of the AND circuit 23 is also at the H level. Therefore, when no transmission current is flowing, the comparator
The output of COM2 goes high and the output of comparator COM3 goes low. Therefore, the transistors Q2 and Q
3 is turned on, and a pulse voltage of +24 V is output to the transmission line 12 from the point B.

The control unit 13 or the controlled unit 14
, The potential of the non-ground terminal (point C) of the resistor r2 rises, and the output of the comparator COM1 becomes H
It falls from the level to the L level.

In synchronization with the fall of the output of the comparator COM1, the output of the one-shot circuit 22 is set for a predetermined time T.
Only after changing to the L level state, it returns to the H level state.

For this reason, once the output of the comparator COM1 falls from the H level to the L level, the output of the AND circuit 23 outputs the L level signal for at least the predetermined time T.

As a result, an H level signal is output from the comparator COM2, and an L level signal is output from the output of the comparator COM3. Therefore, the transistors Q1 and Q
4 is turned on, and a pulse voltage of −24 V is output from the point A to the transmission line 12.

As described above, when the power supply unit 11 detects the transmission current, it reverses the polarity of the output voltage. During the process of inverting the polarity of the output voltage, the power supply 11
, The transmission current temporarily becomes zero. At this time, if the one-shot circuit 22 is not provided, the output of the AND circuit 23 goes to the H level, so that a voltage of +24 V is again output from the point B.

However, in this embodiment, the one-shot circuit 2
2, the output of the AND circuit 23 is kept at L level only for a certain time T after the output of the comparator COM1 falls. Therefore, even if the transmission current temporarily becomes zero as shown in FIG. The polarity of the output voltage of the unit 11 is not inverted, and oscillation can be prevented.

In the first embodiment, the gate of the AND circuit 23 is closed for a certain time T after the output of the comparator COM1 falls by the one-shot circuit 22. As shown in the figure, the comparator CO
The output of M1 is connected to a NAND circuit 51, capacitors C31, r31, r
32, a comparator comprising a circuit comprising a NAND circuit 52
The gate of the AND circuit 23 may be closed for a predetermined time T after the output level of COM1 falls.

Next, a signal transmission system according to a second embodiment of the present invention will be described with reference to FIGS. The overall configuration diagram of the remote monitoring and control system according to the signal transmission system of the second embodiment is the same as that of FIG. 1, and the configurations of the control unit 13 and the controlled unit 14 are also the same as those of FIGS. The detailed configuration is omitted.

In the second embodiment, the configuration of the power supply unit 11 is different from that of the first embodiment. Hereinafter, a detailed configuration of the power supply unit 11 will be described with reference to FIG.

In FIG. 8, reference numerals 61 and 62 represent, for example, 24
V battery. The cathode of the battery 61 and the anode of the battery 62 are connected and the connection point is grounded. The voltage of 5 V is shaped at the anode of the battery 61 via the power supply circuit 63.

COM11 is a comparator. The output of the comparator COM11 is an npn transistor Q31.
And the pnp transistor Q3
2 base. The emitter of the transistor Q31 and the emitter of the transistor Q32 are connected, and the connection point E is connected to one transmission line of the transmission line 12. Further, a DC voltage of +24 V is supplied to the collector of the transistor Q31, and −2 V is supplied to the collector of the transistor Q32.
A DC voltage of 4V is supplied.

When the output level of comparator COM11 is at the H level, transistor Q31 conducts.
A voltage of + 24V is output to the connection point E, and the comparator CO
When the output level of M11 is at the L level, the transistor Q32 conducts, so that a voltage of −24 V is output to the connection point E.

The connection point E is grounded via resistors r41 and r42. The output voltage of the power supply unit 11 is detected based on the voltage generated at the non-ground terminal of the resistor r42. This resistance r
The non-ground side terminal of 42 is compared via resistors r43 and r44.
Connected to the + terminals of COM12 and COM13, respectively. A voltage of +15 V is input to the negative terminal of the comparator COM12, and a voltage of -15 V is input to the negative terminal of the comparator COM13 as a reference voltage.

One transmission line of the transmission line 12 is grounded via a transmission current detecting resistor r45. The non-ground side terminal of the resistor r45 is connected to the + terminal of the comparator COM14 via the resistor r46. A reference voltage for detecting +500 mA is input to the negative terminal of the comparator COM14.

Further, the non-ground side terminal of the resistor r45 is connected to the + terminal of the comparator COM15 via the resistor r49. -500mA is connected to the-terminal of this comparator COM15.
Is input.

The outputs of the comparators COM12 to COM15 are connected to the bases of the transistors Q33 to Q36, respectively. The emitters of these transistors Q33 to Q36 are grounded.

The collectors of the transistors Q33 and Q35 are input to the NAND circuit 64, and the transistors Q34 and Q36
Is input to the NAND circuit 65. The output of the NAND circuit 64 is input to a RS flip-flop 71 composed of NOR circuits 66 and 67 as the set terminal S and the output of the NAND circuit 65 as the reset terminal R.

The Q output of the flip-flop 71 is input to the + terminal of the comparator COM11. This comparison
The COM11 outputs an H level signal when the Q output is at an H level, and outputs an L level signal when the Q output is at an L level.

Next, the operation of the second embodiment of the present invention configured as described above will be described. In the second embodiment, the S input and the R input of the flip-flop and the Q current are larger than the voltage at the connection point E and the current flowing through the resistor r45.
The output is as shown in FIG.

As described above, since the output voltage level of the power supply unit 11 is switched by detecting the output voltage and the transmission current of the power supply unit 11, the same effect as that of the first embodiment can be obtained.

[0059]

As described above in detail, according to the present invention, a plurality of control units and a plurality of controlled units are connected to the transmission line from the power supply unit, and the power supply unit is transmitted from the control unit or the controlled unit. When a current mode signal is received, the polarity of the output voltage is changed so that a control signal is transmitted and received between the control unit and the controlled unit. And a signal transmission method capable of preventing oscillation of a high voltage.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a remote monitoring control system according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a detailed configuration of a power supply unit according to the embodiment.

FIG. 3 is a circuit diagram showing a detailed configuration of a controlled unit according to the embodiment.

FIG. 4 is a circuit diagram showing a detailed configuration of a control unit according to the embodiment.

FIG. 5 is an exemplary view showing a format of transmission data transmitted via a transmission line according to the embodiment;

FIG. 6 is a view showing a voltage and a transmission current output from the power supply unit to the transmission line according to the embodiment.

FIG. 7 is a diagram showing a modification of the power supply unit of the first embodiment.

FIG. 8 is a circuit diagram showing a detailed configuration of a power supply unit according to a second embodiment of the present invention.

FIG. 9 is a diagram showing a relationship between Q outputs of flip-flops.

[Explanation of symbols]

11 power supply unit, 12 transmission line, 13 control unit, 14 controlled unit.

Claims (2)

(57) [Claims] 1. A two-wire transmission line, a bipolar voltage output means for outputting a bipolar voltage signal to the two-wire transmission line, and an output level indicating the polarity of the bipolar voltage signal output from the bipolar voltage output means Designation means for designating, a current change detection means for detecting a change in current flowing through the transmission line, and when a change in current is detected by the current change detection means, inverts the output level of the designation means and thereafter keeps the output level constant Means for prohibiting switching of the designation means for time. 2. A two-wire transmission line, a bipolar voltage output means for outputting a bipolar voltage signal to the two-wire transmission line, and an output level indicating the polarity of the bipolar voltage signal output from the bipolar voltage output means. Designation means, a voltage detection means for detecting a voltage supplied to the two-wire transmission line, a current detection means for detecting a current flowing through the two-wire transmission line, and a voltage detected by the voltage detection means And the current detection
If the current detected by the output means is zero,
Switching means for holding the output level of the means and switching the output level of the designation means based on the voltage detected by the voltage detection means and the current detected by the current detection means. Signal transmission method.