JPS63254840A - Full duplex communication interface unit - Google Patents

Abstract

PURPOSE:To save wiring by forming a control signal in response to room temperature and sending the signal so as to apply power supply and signal transmission/reception simultaneously. CONSTITUTION:A controller 1 fetching room temperature data of a vinyl house 19 to control the ventiration, a room ventilation controller 20 and a full duplex communication interface unit 3 are provided. The room temperature of the house 19 is measured via a digital thermometer 18 and an interface 8 to turn on a switch SW 2 and the current change of the resistor (r) by a synthesized constant current by power supplies 10, 5 is fed to the controller 1 via an amplifier 26. The SW1 is switched by using a control signal 2 in response to room temperature, voltages 24, 22 are selected and the power of the power supply 5 is given to the circuit 8 and each VC temrinal of the thermometer 18 via the constant current source. The motor 14 is driven by a control signal 9 via each VC terminal for the circuit 8 and the thermometer 18 and a constant voltage circuit 6 thereby applying ventilation. As a result, the room temperature is kept to a prescribed value.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a full-duplex communication interface unit, and in particular to a full-duplex communication interface unit for connecting a control device such as a personal computer and terminal equipment, etc. for signal transmission. This invention relates to a full-duplex communication interface unit.

[Conventional technology]

Normally, in a full-duplex data communication system, a data transmitting device and a data receiving device are installed on both the data transmitting side and the data receiving side, and signal transmission between the two is performed via a communication interface unit. .

FIG. 4 shows the overall configuration of an example of an automatic ventilation system for a greenhouse in which this type of data communication is performed. In FIG. 4, 51 is a control device, 52 is a signal transmission line, 53 is an interface, 54 is a digital thermometer, 55 is a DC power supply, 56 is a motor, 57 is a transistor, 58 is an SSR,
59 indicates a vinyl greenhouse, and R51 and R52 indicate resistance.

Parallel data indicating the room temperature from the digital thermometer 54 is converted into serial data by the interface 53, and sent to the control device 51 via the signal line 52A of the signal transmission path 52.
transmitted to. The control device 51 determines whether the room temperature of the greenhouse 59 is above a predetermined value based on this data, and as a result, if the room temperature is above the predetermined value,
A control signal for turning on the transistor 57 is sent to the interface 53 via the signal line 52B. As a result, the 5SR 58 becomes conductive and the motor 56 is driven to rotate, thereby ventilating the room. The control device 51 controls the transistor 5 when the room temperature falls below a predetermined value while ventilation is being performed.
A control signal for turning off the motor 7 is sent to the interface 53 via the signal line 52B to stop the rotation of the motor 56. In this way, in controlling the temperature of the greenhouse 59, the control device 51 receives a signal indicating temperature data through the signal line 52A1 and the signal line 5 transmits a control signal for the motor 56.
At least three wires are required: 2B and a common signal line 52C (earth line) for the signal lines 52A and 52B.

[Problem that the invention seeks to solve]

However, in the conventional communication interface unit, when the distance between the control device 51 and the greenhouse 59 is short, the wiring cost of the signal line accounts for a small proportion of the overall system price, but when the two are far apart, In some cases, it becomes large.

For this reason, generally, one device transmits signals via two signal lines, and the other device receives signals, and after the specified data transmission and reception is completed, both devices transmit and receive signals. A half-duplex transmission method is used in which signals are transmitted alternately with the signals reversed. Although this method is beneficial in terms of reducing wiring costs, it is difficult to set conditions for switching timing between transmission and reception, and the software of the control device that controls transmission and reception becomes complicated. In addition, in such a control system, when it is necessary to urgently communicate abnormal system operation between devices, if the device that reports the abnormality does not have the right to send a signal, the abnormal state will be maintained until the other party finishes transmitting. There are problems that cannot be communicated. Furthermore, if a power source for an interface or the like is not provided on the device to be controlled, wiring for the power source is required separately from the signal line, which increases wiring costs.

SUMMARY OF THE INVENTION In view of the problems of the prior art described above, it is an object of the present invention to provide a full-duplex communication interface unit that can simultaneously supply power and transmit and receive signals, and reduce wiring costs.

[Means for solving problems]

The full-duplex communication interface unit according to the present invention is a full-duplex communication interface unit for transmitting control signals from a control device such as a personal computer to a terminal device to be controlled and receiving an output signal from the terminal device, etc. In the interface unit, a first constant voltage power supply unit outputs a power supply voltage for the terminal equipment, etc. to be controlled, and a second constant voltage power supply unit generates a voltage signal corresponding to a control signal from the control device. a selection means for selecting a power supply voltage from the first constant voltage power supply means and a voltage signal from the second constant voltage power supply means based on a control signal output from the control device; a signal transmission means for transmitting an output signal from the means; and a first constant for causing a current corresponding to a power supply voltage from the first constant voltage power supply means outputted from the selection means to flow through the signal transmission means. a current power supply means; a third constant voltage power supply means that outputs a constant power supply voltage based on the constant current output from the first constant current power supply means;
A first extracting control signal corresponding to the voltage signal from the second constant voltage power supply means from the transmission signal of the signal transmission means.
a second signal extracting means for causing a current corresponding to an output signal from the terminal equipment, etc., which operates based on the control signal extracted by the first signal extracting means, to flow through the signal transmitting means; a constant current power supply means, a current intermittent means for intermittent the flow of current output from the second constant current power supply means based on an output signal from the terminal device, etc.; the first constant current power supply means; a second constant current means for detecting the output current from the signal transmission means; and a second constant current means for extracting an output signal from the terminal device etc. from the detection signal detected by the current detection means. The apparatus is characterized in that it is comprised of a signal extraction means.

[For production]

In the full-duplex communication interface unit according to the present invention, the power supply voltage for the terminal equipment to be controlled is outputted from the first constant voltage power supply means, and the voltage signal corresponding to the control signal from the control device is outputted from the first constant voltage power supply means. The voltage signal is output from the second constant voltage power supply means, and the power supply voltage from the first constant voltage power supply means and the voltage signal from the second constant voltage power supply means are selected by the selection means. The output signal from the selection means is transmitted to the signal transmission means, and a constant current corresponding to the power supply voltage from the first constant voltage power supply means flows to the signal transmission means by the first constant current power supply means. A constant voltage power supply voltage based on the constant current output from the first constant current power supply means is output from the third constant voltage power supply means.

Further, the first signal extraction means extracts a control signal corresponding to the voltage signal from the second constant voltage power supply means from the transmission signal of the signal transmission means, and the terminal equipment, etc. operates based on the extracted control signal. A current corresponding to the output signal is caused to flow to the signal transmission means by the second constant current power supply means. The flow of current outputted from the second constant current power supply means is interrupted by the current intermittent means based on the output signal from the terminal device etc., and the output from the first constant current power supply means and the second constant current means is outputted from the first constant current power supply means and the second constant current means. The current is detected from the transmission signal of the signal transmission means by the current detection means, and the output signal from the terminal device or the like is extracted from the detected signal by the second signal extraction means.

As a result, data can be transmitted and received between the control device and the terminal device, etc. to be controlled simultaneously using voltage signals and current signals, and the X source voltage for the terminal device, etc. can be transmitted from the control device side together with the voltage signal. Can be supplied.

〔Example〕

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a full-duplex communication interface unit according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a full-duplex communication interface according to the present invention.
The greenhouse automatic ventilation system to which the unit is applied is shown, and the greenhouse automatic ventilation system is
A control device 1 mainly includes a personal computer or the like that takes in room temperature data of the greenhouse 19 and controls and instructs predetermined indoor ventilation based on this room temperature data; It is composed of a ventilation control device 20 that performs ventilation, and a full-duplex communication interface unit 3 according to the present invention for connecting the control device 1 and the ventilation control device 20 and transmitting and receiving signals between them. There is.

The digital control signal 2 from the control device 1 is sent to the analog switch SW of the full-duplex communication interface unit 3.
1, and the analog switch SWl performs a switching operation in response to this control signal 2. Analog switch SW
1 has 2 contacts (contact a.

b) method, and the constant voltage voltage R<output voltage E is on the contact a side.
l) The positive electrode of the constant voltage power supply (output voltage E2) 24 is connected to the contact side of the positive electrode 22 (however, E
l<E2). The negative electrode of the constant voltage power supply 22 and the constant voltage power supply 24
One end of the capacitor C2 is connected to this common connection point, and the other end of the capacitor C2 is connected to one end of the input end of the amplifier 26. Further, a resistor r for detecting current is connected to the common connection point, and this resistor r is connected to one end of the input terminal of the amplifier 20.

There are two signal lines 4A on the output side of the analog switch SWI.
, 4B is connected to the signal line 4A, and the signal line 4B is connected to the input end of the amplifier 26 to which the resistor r is connected.

A constant current power source 5.10 and a capacitor C1 are connected to the signal line 4A of the signal transmission path 4, and a constant voltage circuit 6 is connected to the output side of the constant current power source (output current 1) 5. This constant voltage circuit 6 supplies a power supply voltage based on the output current from the constant current power supply 5 to the power supply receiving terminal VC of the bidirectional interfurniture 8 . The other end of the capacitor C1 is connected to the signal input terminal IN of the bidirectional interface 8, and the output side of the constant current power supply (output current 12) 10 receives a digital signal from the signal output terminal S of the bidirectional interface 8. Analog switch S that turns ON and ○FF in response to 9.
5) connected to W2. The output side of the analog switch SW2 is connected to the signal line 4B and the ground terminal of the bidirectional interface 8.

The interface 8 outputs a predetermined output signal from the signal output terminal OUT based on a control signal inputted to the signal input terminal IN.

The base of a transistor 12 of the ventilation control device 20 is connected to the signal output terminal OUT of the bidirectional interfunis 8, and the collector of this transistor 12 is connected to the photocoupler 9.
The cathode of the light emitting diode 10 is connected, and the emitter is grounded.

The anode of the light emitting diode 10 is connected to the output side of the constant voltage circuit 6 via a resistor R1, so that a predetermined current flows through the light emitting diode 10. Light 11 from the light emitting diode 10 is received by a photodiode 13, whose anode is connected to the voltage JV via a resistor R2, and its cathode is connected to the base of a transistor 16, respectively. The collector of the transistor 16 is connected to a ventilation motor 14 connected to the power supply (2), and the emitter is grounded.

A digital thermometer 18 is connected to the data input terminal P/S of the interface 8 . digital thermometer 18
The power supply voltage from the constant voltage circuit 6 is supplied to the power supply terminal VC.

Next, an overview of the operation of the automatic ventilation system for a greenhouse constructed as described above will be described with reference to FIGS. 2 and 3.

The room temperature of the greenhouse 19 is detected by a digital thermometer 18, and parallel data from the digital thermometer 18 indicating the indoor temperature t is input to the data input terminal P/S of the interface 8. The interface 8 converts the manually input parallel data into serial data, and converts this serial data into a switch signal 9 of the analog switch SW2 (Fig. 2(a)).
). As a result, the analog switch SW2 is turned on based on the high level of the switch signal 9.
At this time, the constant current 12 from the constant current power supply 10 becomes the composite current (11+I2
) flows through the resistance r (see FIG. 2(b)). A voltage drop occurs in the resistor r as the current changes, and the current signal represented by this voltage drop has its direct current component removed by the capacitor C2 and is input to the amplifier 26 (see FIG. 2(C)). The amplifier 26 amplifies the voltage of this human input signal to TTL level and outputs it to the control device 1. Regulation? 11 The device 1 determines whether the room temperature of the greenhouse 19 is above a predetermined value based on the output signal from the amplifier 26, and if it is determined that the room temperature is above the predetermined value, ventilation is performed. A digital control signal 2 (see FIG. 3(a)) for driving the motor 14 is output to the analog switch SWI in order to lower the room temperature to a predetermined value. The analog switch SWI switches D based on this control signal 2.
When is at a high level, the switch is switched to the contact side and the output voltage (E2) from the power supply voltage 24 is selected, and when it is low level, the switch is switched to the contact a side and a constant voltage voltage is selected. 22 (El) is selected. Analog switch SW
The output voltage from the constant voltage power supply 22, 24 selected by 1 is output to the signal transmission path 4 (see FIG. 3(b)). As a result, the output current 11 from the constant current power supply 5 is converted into a constant voltage El (power supply voltage) by the constant voltage circuit 6, and then supplied to each power supply receiving terminal VC of the digital thermometer 18 of the inter-fnis 8 digital thermometer 18. In addition, the control signal (
(see FIG. 3(d)) is input to the signal input terminal IN of the interfinice 8. The interfunis 8 receives this digital control signal and turns on the transistor 12 of the ventilation control device R20 from the signal output terminal OUT.
It continues to output based on the level signal.

As a result, the transistor 12 is turned on, the light emitting diode 10 of the photocoupler 9 emits light, and the light 11 from the light emitting diode 10 is received by the photodiode 13. As a result, the photodiode 13 is turned on,
Accordingly, the transistor 16 is turned on, and the motor 14 is driven. The room temperature of the greenhouse 9 is ventilated by driving the motor 14, and the warm air stored in the room is discharged outside the greenhouse 9, so that the room temperature drops to a predetermined value.

As described above, in the greenhouse automatic ventilation system of this embodiment, the room temperature inside the greenhouse 19 is indicated by the current flowing through the signal transmission path consisting of two signal lines of the full-duplex communication interface unit. It is configured so that a control signal corresponding to the room temperature based on the current value is expressed as a voltage and transmitted to the ventilation control device in the greenhouse.

In addition, according to the full-duplex interface unit according to the present invention, from the control device to the terminal equipment to be controlled,
By superimposing the voltage signal on the power supply voltage and transmitting it,
The terminal equipment receives the power supply voltage separated from the received signal and at the same time performs control based on the voltage signal, and the data signal output from the terminal equipment to the control device is expressed as a current flowing through the signal transmission path. ing.

Note that the power source of the full-duplex communication interface unit 2) does not need to be a DC constant voltage power supply or a DC constant current power supply, and may be an AC constant voltage power supply or an AC constant current power supply.

(Effects of the Invention) As described above, in the full-duplex communication interface unit according to the present invention, a control signal is transmitted from a control device such as a personal computer to a terminal device to be controlled, and a control signal is transmitted from the terminal device, etc. In a full-duplex interface unit for receiving an output signal, a first constant voltage power supply means outputs a power supply voltage of a terminal device, etc. to be controlled, and a voltage signal corresponding to a control signal from a control device is generated. Selection of selecting a second constant voltage power supply means, a power supply voltage from the first constant voltage power supply means, and a voltage signal from the second constant voltage power supply means based on a control signal output from the control device. means, a signal transmission means for transmitting an output signal from the selection means, and a first means for causing a current corresponding to the power supply voltage from the first constant voltage power supply means outputted from the selection means to flow through the signal transmission means. constant current power supply means; third constant voltage power supply means for outputting a constant voltage power supply voltage based on the constant current output from the first constant current power supply means; a first signal extracting means for extracting a control signal corresponding to the voltage signal from the voltage power source means; and a first signal extracting means for extracting a control signal corresponding to the voltage signal from the voltage power supply means; a second constant current power supply means for causing current to flow through the signal transmission means;
Current detection means for intermittent flow of current output from the second constant current power supply means based on an output signal from a terminal device, etc. Output current from the first constant current power supply means and the second constant current power supply means current detection means for detecting from the signal transmission means;
Since the second signal extraction means extracts the output signal from the terminal equipment etc. from the detection signal detected by the current detection means, data exchange between the control device and the terminal equipment etc. to be controlled is reduced. Transmission and reception can be performed simultaneously using voltage signals and current signals, and various controls can be performed without interfering with data transmission and reception timing.

Furthermore, since signals in which the power supply voltage and voltage signals are superimposed and current signals can be transmitted between devices and devices via two signal lines, wiring costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 shows a full-duplex communication interface according to the present invention.
A block diagram showing the overall general configuration of the automatic ventilation system for a greenhouse to which the unit is applied. Figure 2 shows an example of the current signal waveform in the full-duplex communication interface unit of the automatic ventilation system for the greenhouse shown in Figure 1. Figure 3 is a waveform diagram showing an example of the voltage IN waveform in the full-duplex communication interface unit of the automatic greenhouse ventilation system shown in Figure 1, and Figure 4 is a waveform diagram of the conventional automatic ventilation system for greenhouses. Overall system overview @
FIG. 1...Control device, 4...Signal transmission path, 5゜lO
...Constant current power supply, 8...Bidirectional interface, 18...Digital thermometer, 22.24...
Constant voltage power supply, 26...Amplifier, SWi, SW2
...Analog switch.

Claims (1)

[Claims] (1) In a full-duplex communication interface unit for transmitting control signals from a control device such as a personal computer to a terminal device, etc. to be controlled and receiving an output signal from the terminal device, etc., the device to be controlled a first constant voltage power supply means that outputs a power supply voltage for terminal equipment, etc.; a second constant voltage power supply means that generates a voltage signal corresponding to a control signal from the control device; and the first constant voltage power supply means. and the power supply voltage from the second
a selection means for selecting a voltage signal from a constant voltage power supply means based on a control signal output from the control device; a signal transmission means for transmitting an output signal from the selection means; and a signal transmission means for transmitting an output signal from the selection means. a first constant current power source that causes a current corresponding to the power supply voltage from the first constant voltage power source to flow through the signal transmission means; and a constant current that is output from the first constant current power source. a third constant-voltage power supply means that outputs a constant-voltage power supply voltage based on the reference voltage; and a first constant-voltage power supply means that extracts a control signal corresponding to the voltage signal from the second constant-voltage power supply means from the transmission signal of the signal transmission means.
a second signal extracting means for causing a current corresponding to an output signal from the terminal device, etc. that operates based on the control signal extracted by the first signal extracting means to flow through the signal transmitting means.
a current intermittent means for intermittent current flow output from the second constant current power supply means based on an output signal from the terminal device, etc.; and the first constant current power supply means. a current detection means for detecting an output current from the second constant current means from the signal transmission means; and a second current detection means for extracting an output signal from the terminal equipment etc. from a detection signal detected by the current detection means. A full-duplex communication interface unit comprising: a signal extraction means; and a full-duplex communication interface unit.