JPH0241239B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a data transmission circuit that transmits control data and the like in a two-wire system.

BACKGROUND ART FIG. 1 is an electrical circuit diagram of a conventional data transmission circuit that transmits control data and the like. The main body processing section A1 is composed of a power source E1, photocouplers 4, 5, and 6, and resistors 7, 8, and 9. The operating section B1 has switches 1, 2, and 3, one end of the switch 1 is connected to one end of the resistor 7 via a line l1, one end of the switch 2 is connected to one end of the resistor 8 via a line l2, One end of switch 3 is connected to one end of resistor 9 via line l3. switch 1,
The other ends of 2 and 3 are respectively grounded via line l4. When switch 1 is turned on, current from power source E1 flows through photocoupler 4 and resistor 7 through line l1 in the direction of arrow F1, and through line l4 to ground. By this, photocoupler 4
operates and sends out a signal from output Q1. When the switch 2 is turned on, the current from the power source E1 flows through the photocoupler 5 and the resistor 8 to the line l2 at the arrow F.
2 and flows to ground via line 14, and photocoupler 5 operates. When the switch 3 is turned on, the current from the power source E1 flows through the photocoupler 6 and the resistor 9 through the line 13 in the direction of the arrow F3, and through the line 14 to ground, and the photocoupler 6 is activated. As described above, when switch 1 is turned on, a signal is sent from the output Q1 of photocoupler 4, when switch 2 is turned on, a signal is sent from output Q2 of photocoupler 5, and when switch 3 is turned on, a signal is sent from output Q3 of photocoupler 6. be done. Electrical equipment and the like are controlled by such signals.

As described above, in the circuit shown in FIG. 1, the number of transmission lines for transmitting signals requires a large number of switches and a number of common lines, which makes wiring complicated and increases costs.

Purpose The purpose of the present invention is to solve the above-mentioned technical problem,
The purpose of the present invention is to provide a data transmission circuit that uses two-wire wiring to transmit signals and achieves low cost.

The present invention includes: (a) an AC power source E2; (b) first lines l5 and l7 connected to one end of the AC power source E2; and (c) a second line connected to the other end of the AC power source E2. l6, l8, and (d) a pair of first and second impedance elements 3 connected in series to the first lines l5, l7.
(e) a first diode 38 connected in parallel with the first impedance element 36; (f) a first diode 38 connected in parallel with the second impedance element 37 and in the opposite direction to the first diode 38; (g) first level discrimination circuits 32 and 34 that detect the potential difference between both ends of the first impedance element 36 to discriminate the level; (h) the second impedance element 37 second level discrimination circuits 33 and 35 that detect the potential difference between both ends of the switch and discriminate the level; (i2) a second series circuit including a second switch 19 and a fourth diode 17 provided in the same direction as the second diode 39; i3) Third switch 2
0, including at least two of the following;
The first lines l5, l7 and the second line l
This data transmission circuit is characterized in that it includes such an operation section B2 connected between the terminals 6 and 18.

Embodiment FIG. 2 is an electrical circuit diagram of the basic configuration of the present invention. In the main body processing section A2, the terminal a1
is connected to the power supply Vcc via the resistor 11, and also to the collector of the phototransistor 12a of the photocoupler 12. The terminal a2 is connected to the power supply Vcc via the resistor 10, and is also connected to the collector of the phototransistor 13a of the photocoupler 13.
The cathode of the light emitting diode 12b of the photocoupler 12 is connected to one end of the AC power source E2 via the line l7, and the anode of the light emitting diode 12b is connected to the line l5 via the resistor 14. The anode of the light emitting diode 13b of the photocoupler 13 is connected to one end of the AC power supply E2 via the line l7,
The cathode of the light emitting diode 13b is connected to the line l5 via the resistor 14. The other end of AC power supply E2 is connected to line l6 via line l8 and resistor 15.

The operating section B2 has diodes 16, 17 and switches 18, 19, 20. diode 1
The anode of switch 6 is connected to line l5, and its cathode is connected to one end of switch 18. The other end of switch 18 is connected to line l6. The cathode of diode 17 is connected to line l5,
Its anode is connected to one end of switch 19. The other end of switch 19 is connected to line l6. Both ends of switch 20 are connected to line l5 and line l6.

The operation will be explained below with reference to FIG. FIG. 3 1 shows the output waveform of the AC power source E2. When switch 18 is turned on, the output shown in FIG. 3 is rectified by diode 16, and the signal shown in FIG. 3 flows through line 15 and line 16. The photocoupler 13 is activated by this signal and sends out a signal as shown in FIG. 3 from the terminal a2. At this time, the signal at the terminal a1 is at a high level as shown in FIG. 36.

When switch 19 is turned on, the signal is rectified by diode 17, and the signal shown in FIG. 3 flows through line 15 and line 16. The photocoupler 12 operates in response to this signal and sends out a signal as shown in FIG. 38 from the terminal a1. At this time, terminal a2
The signal is at high level as shown in FIG. 37.

When switch 20 is turned on, or when switches 18 and 19 are turned on at the same time, signals as shown in FIG. 3 flow through lines 15 and 16. This signal causes the photocoupler 12 and the photocoupler 13 to operate, and a signal as shown in FIG. 3 is sent out from the terminal a2, and a signal as shown in FIG. 3 is sent out from the terminal a1.

In this way, three modes can be distinguished based on the difference in the specifications of the signals sent from the terminals a1 and a2. In other words, it is possible to determine which of the switches 18, 19, and 20 is being operated, or whether the switch 18 is on, the switch 19 is on, or the switches 18 and 19 are on simultaneously. Note that the operating section B2 shown in FIG. 2 can be replaced with the operating section b2 shown on the left. Operation part b2
are the diodes 21, 22 and the switch 23,
It has 24. The switch 23 corresponds to the switch 18 of the operating section B2, and the switch 24 corresponds to the switch 19 of the operating section B2, and their operations are the same.

FIG. 4 is an electrical circuit diagram of one embodiment of the present invention. In FIG. 4, components corresponding to those shown in FIG. 2 are given the same reference numerals. In the main body processing section A3, the terminal a1 is connected to the power supply Vcc via the resistor 31, and is also connected to the output terminal of the voltage comparator 32. Terminal a2 is connected to power supply Vcc via resistor 30, and also to the output terminal of voltage comparator 33. One input terminal of the voltage comparator 32 is connected to the output terminal of the differential amplifier 34, and the other input terminal of the voltage comparator 32 is given a positive reference potential. One input terminal of the voltage comparator 33 is connected to the output terminal of the differential amplifier 35.
A negative reference potential is applied to the other input terminal of No. 3. That is, the voltage comparator 32 and the differential amplifier 34
a circuit comprising a first level discrimination circuit,
A circuit including voltage comparator 33 and differential amplifier 35 constitutes a second level discrimination circuit. Differential amplifier 3
Both input terminals of the differential amplifier 35 are connected to a resistor 36, which is a first impedance element, and both input terminals of the differential amplifier 35 are connected to a resistor 37, which is a second impedance element. The anode of the diode 38 is connected to the resistor 3
6 and the line 17, and the cathode of the diode 38 is connected to the other end of the resistor 36 and the cathode of the diode 39. diode 3
The cathode of diode 9 is connected to one end of resistor 37, and the anode of diode 39 is connected to the other end of resistor 37 and line l5.

Both ends of the AC power supply E2 are line l7 and line l.
8. The line l8 is connected to the switch 1 of the operating section B2 via the resistor 40 and the line l6.
8, 19, and 20. The other end of switch 18 is connected to the cathode of diode 16, and the other end of switch 19 is connected to the anode of diode 17. anode of diode 16,
The cathode of diode 17 and the other end of switch 20 are connected to line 15.

The operation will be described below with reference to the waveform diagram of FIG. 3. When switch 18 is turned on, line l5
A signal shown in FIG. 32 flows through. This signal is
The current flows through the resistor 37 in the direction indicated by arrow F5, but does not flow through the diode 39. This generates a voltage across the resistor 37, which is amplified by the differential amplifier 35. The signal input to the differential amplifier 34 is lower than the forward voltage of the diode 38.
The voltage comparator 33 removes noise from the output of the differential amplifier 35 and sends out a signal as shown in FIG. 3. When switch 19 is turned on, a signal shown in FIG. 3 flows through line 15. This signal flows through the resistor 36 in the direction indicated by the arrow F4 and through the diode 3.
It doesn't flow to 8. This generates a voltage across resistor 36, which voltage is amplified by differential amplifier 34. The signal input to the differential amplifier 35 is lower than the forward voltage of the diode 39. The voltage comparator 34 removes noise from the output of the differential amplifier 34 and sends out a signal as shown in FIG. 38. When switch 20 is turned on, or when switches 18 and 19 are turned on at the same time, a signal as shown in FIG. 3 flows through line 15. This signal causes resistor 37 and resistor 36 to
Voltages are generated alternately. Therefore, the voltage comparator 33 sends out the signal shown in FIG. 3, and the voltage comparator 32 sends out the signal shown in FIG. 3, 10.

Effects As described above, according to the present invention, the first and second
The first and second level discrimination circuits 32, 34; 33, 35 detect the direction of the current from the AC power supply E2 flowing through the lines l5, l7; l6, l8 of the switch 18, 1
9 and 20 switching states can be determined. Furthermore, a pair of lines l5, l7; l6,
I8 makes it possible to transmit data corresponding to a maximum of four switching states, including a state in which all switches are off.

Further, in the present invention, the first and second level discrimination circuits 32, 34; 33, 35 include the first and second impedance elements 36,
37 detects the current flowing through the first lines l5 and l7, the current flowing through the lines can be reduced. Therefore, small and inexpensive components with low current capacity can be used for switches and diodes.

Furthermore, the first and second impedance elements 3
Since the first and second diodes 38 and 39 are connected in parallel between both ends of 6 and 37, respectively,
Regarding the forward direction of each diode 38, 39, the input voltage of each level discrimination circuit 32, 34; 33, 35 is suppressed to be higher than the forward direction voltage of the diode, and is protected from generation of excessive voltage due to noise etc. Can be done. Further, since noise below the discrimination level of the level discrimination circuit can be removed, accurate data can be transmitted.

[Brief explanation of drawings]

Figure 1 is an electrical circuit diagram of a conventional data transmission circuit.
FIG. 2 is an electric circuit diagram of the basic configuration of the present invention,
FIG. 3 is a waveform diagram for explaining the operation of the circuit of FIG. 2, and FIG. 4 is an electric circuit diagram of an embodiment of the present invention. A2, A3...Main processing unit, B2...Operation unit,
10, 11, 14, 15, 30, 31, 36, 3
7,40...resistance, 12,13...photocoupler,
16, 17, 38, 39...diode, 18,
19, 20... Switch, 32, 33... Voltage comparator, 34, 35... Differential amplifier, E2... AC power supply, l5-l8... Line.

Claims (1)

[Claims] 1 (a) an AC power source E2; (b) first lines l5 and l7 connected to one end of the AC power source E2; and (c) connected to the other end of the AC power source E2. second lines l6, l8; and (d) a pair of first and second impedance elements 3 connected in series to the first lines l5, l7.
(e) a first diode 38 connected in parallel with the first impedance element 36; (f) a first diode 38 connected in parallel with the second impedance element 37 and in the opposite direction to the first diode 38; (g) first level discrimination circuits 32 and 34 that detect the potential difference between both ends of the first impedance element 36 to discriminate the level; (h) the second impedance element 37 second level discrimination circuits 33 and 35 that detect the potential difference between both ends of the switch and discriminate the level; (i2) a second series circuit including a second switch 19 and a fourth diode 17 provided in the same direction as the second diode 39; i3) Third switch 2
0, including at least two of the following;
The first lines l5, l7 and the second line l
6, l8;