JPH0210691Y2 - - Google Patents

Description

[Detailed explanation of the idea] This invention relates to a signal transmission device.

Conventionally, in order to monitor and control multiple slave stations with one master station, each slave station was wired with a 2-core dedicated line, or when using a 2-core communication line, each slave station was A tone frequency method was used in which frequencies were assigned as many as the number of control or monitoring items.
Therefore, the price per item is high, and at the same time there is a limit to the number of items that can be monitored and controlled.

Therefore, an object of this invention is to provide a signal transmission device that is inexpensive, has a simple configuration, and is capable of bidirectional communication.

An embodiment of this invention is shown in the drawings. In the drawing, 1 is a signal transmitting/receiving unit of the master station, 4 is two communication lines whose starting ends are connected to the signal transmitting/receiving unit 1 of the master station, and the terminal ends are short-circuited to form a loop, and 2 and 3 are two communication lines. This is a signal transmitting/receiving section of a slave station inserted in series in the middle of line 4.

The signal transmitting/receiving section 1 of the master station includes master station terminals 1a and 1b connected to the starting ends of two communication lines 4, a current limiting resistor 5, and a photocoupler 6 serving as a master station signal transmitting means and a power source selection means. , a diode 7, a power supply 8 that applies a voltage between the master station terminals 1a and 1b so that the master station terminal 1a becomes the positive electrode, and a diode 9.
A voltage is applied between a photocoupler 10 serving as a power supply selection means, a photocoupler 11 serving as a master station signal receiving means, a resistor 12 for current limiting, and master station terminals 1a and 1b so that the master station terminal 1b becomes a positive pole. Power source 13
It consists of

The power supply selection means selects one of the power supplies 8 and 12, the master station signal transmission means changes the current flowing between the master station terminals 1a and 1b by the power supply 8, and the master station signal reception means selects one of the power supplies 8 and 12. The master station terminal 1a,
Detects changes in the current flowing between 1b.

Resistor 5, photocoupler 6, diode 7, and power supply 8
constitutes a transmitter for the flow of signals from the master station to the slave stations (hereinafter referred to as a downlink signal). In addition, the diode 9, photocouplers 10, 11, resistor 12, and power supply 13 are used for the signal flow from the slave station to the master station (hereinafter referred to as
(referred to as an uplink signal).

On the other hand, the signal transmitting/receiving section 2 of the slave station is connected to the master station terminal 1a.
A slave station terminal 2a located on the side, a slave station terminal 2b located on the master station terminal 1b side, and slave station terminals 2a, 2b.
A series circuit of a light emitting diode 14a and a diode 18 of a photocoupler 14 for signal reception connected in between so that the direction from the slave station terminal 2a to the slave station terminal 2b is the forward direction, and a light emitting diode of the photocoupler 14 for signal reception. A signal is connected between the phototransistor 14b of the photocoupler 14 for signal reception that detects changes in the current flowing through the phototransistor 14a and the slave station terminals 2a and 2b so that the direction from the slave station terminal 2b to the slave station terminal 2a is the forward direction. Photocoupler 1 for transmission
6 phototransistor 16b and diode 2
The light emitting diode 16a of the photocoupler 16 for signal transmission changes the current flowing through the phototransistor 16b of the photocoupler 16 for signal transmission. In this case, photocoupler 14 and diode 18 constitute a receiving section, and photocoupler 16 and diode 20 constitute a transmitting section.

The signal transmitting/receiving section 3 of the slave station also has the same configuration as the signal transmitting/receiving section 2, and has slave station terminals 3a, 3b.
, a receiving section composed of a photocoupler 15 and a diode 19 for signal reception, and a transmitting section composed of a photocoupler 17 and a diode 21 for signal transmission. The photocouplers 14 and 15 pass the line current of the downlink signal to the light emitting diodes 14a and 15a, and receive the downlink signal at the phototransistor 14b and 15b side, and the photocouplers 16 and 17
is for returning an upstream signal, and by controlling the current flowing through the light emitting diodes 16a and 17a, the phototransistor 16b or 17b is turned on and off, and the upstream signal is returned.

The operation of this signal transmission device will be explained below. This device is capable of half-duplex communication, in which the upstream signal is inactive during the downlink signal, and the downlink signal is inactive during the upstream signal. be.

First, the downlink signal will be explained. When a current is applied to the light emitting diode 6a of the photocoupler 6 with the phototransistor 10b turned off by stopping the power supply to the light emitting diode 10a of the photocoupler 10 at the time of a down signal, the phototransistor 6b becomes conductive.
Through the communication line 4, power supply 8 → master station terminal 1a → slave station terminal 2a → light emitting diode 14a → diode 18
→ Slave station terminal 2B → Slave station terminal 3a → Light emitting diode 15a → Diode 19 → Slave station terminal 3b → Master station terminal 1b → Resistor 5 → Phototransistor 6b → Diode 7 → Power supply 8, and the light emitting diode 6a is energized. Therefore, current flows only while the phototransistor 6b is on. During that period, the photocouplers 14 and 1 of the signal transmitting and receiving units 2 and 3 of the slave stations
No. 5 phototransistors 14b and 15b become conductive. Detecting this continuity, each slave station receives a downstream signal.

Next, uplink signals will be explained. During the upstream signal, the phototransistor 6b of the photocoupler 6 is non-conductive. A case will be described in which the signal transmitting/receiving section 2 of the slave station returns an uplink signal, but the operation is similar in the case of the signal transmitting/receiving section 3 of the slave station. When the light emitting diode 10a is energized and the phototransistor 10b is in a conductive state, the power supply 13→
Resistor 12 → Light emitting diode 11a → Phototransistor 10b → Diode 9 → Master terminal 1b → Slave terminal 3b → Phototransistor 17b → Diode 21 → Slave terminal 3a → Slave terminal 2b → Phototransistor 16b → Diode 20 → Slave station Terminal 2a→
A current flows through the path from the master station terminal 1a to the power supply 13.
In this case, the light emitting diodes 16a, 17a of the photocouplers 16, 17 of the signal transmitting/receiving sections 2, 3 of the slave stations are conductive. In this state, the signal transmitter/receiver 2 of the slave station
In order to send a signal back to the signal transmitting/receiving section 1 of the master station, the light emitting diode 16a of the photocoupler 16 is used.
The phototransistor 16b is made non-conductive. When the phototransistor 16b becomes non-conductive, the flow of line current is cut off, the light emitting diode 11a of the signal transmitting/receiving section 1 of the master station stops emitting light, and the phototransistor 11b becomes non-conductive. The signal transmitting/receiving section 1 of the master station is this phototransistor 11
The upstream signal from the signal transmitting/receiving section 2 of the slave station is received by detecting conduction/non-conduction of the terminal b. Then, upon completion of the upstream signal, the phototransistor 10b of the photocoupler 10 is made non-conductive. At this time, the phototransistor may be in any state. This is diode 2
This is because 0 and 21 are inserted. When the signal becomes a downstream signal again, the light emitting diode 6a emits light according to the code, and the slave station starts receiving. Here, the signals for each slave station can be easily distinguished by coding both the upstream signal and the downstream signal and assigning a code to each slave station. The role of the diodes 18 and 19 is to prevent a reverse voltage from being applied to the light emitting diode 14a or 15a when the phototransistor 16b or 17b becomes non-conductive when the slave station returns a signal. . Moreover, the diodes 20 and 21 are
If the light emitting diodes 14a, 15a or the components or circuits of the diodes 18, 19 become open due to some kind of failure, the phototransistor 16
This is to prevent a high reverse voltage from being applied to the terminals b and 17b.

As described above, the signal transmission device of this embodiment uses photocouplers 6, 11, 14 to 17, which are unidirectional elements, as signal transmitting/receiving means in the signal transmitting/receiving sections 1, 2, and 3 of the master station and slave stations. The starting ends of two communication lines 4 are connected to the signal transmitting/receiving section 1 of the station, and the terminal ends of the communication lines 4 are short-circuited to form a loop, and the signal transmitting/receiving sections 2 of a plurality of slave stations are connected in the middle of the communication line 4. , 3 are the polarities of the transmitting power source 8 and the receiving power source 13 of the signal transmitting/receiving section 1 of the master station and the respective photocouplers 14 to 17 of the receiving section and transmitting section of the signal transmitting/receiving sections 2 and 3 of the slave stations 2 and 3. and diode 1
8 to 21 are inserted and connected so that the polarities of terminals 8 to 21 are matched, that is, the slave station terminals 2a and 3a are connected to the master station terminal 1a side, and the slave station terminals 2b and 3b are respectively connected to the master station terminal 1b side, Since the downlink signal and the uplink signal are transmitted as changes in current flowing in opposite directions in the loop, highly practical bidirectional communication can be performed with an inexpensive and simple configuration.

As described above, the signal transmission device of this invention includes a signal transmitting/receiving section of a master station, two communication lines whose starting ends are connected to the signal transmitting/receiving section of the master station and whose terminal ends are short-circuited, and the two communication lines. first and second master station terminals, comprising signal transmitting/receiving units of a plurality of slave stations inserted in series in the middle of the line, and connecting the signal transmitting/receiving units of the master station to the starting ends of the two communication lines; and,
a first power supply that applies a voltage between the first and second master station terminals so that the first master station terminal becomes positive; and a first power supply that applies a voltage between the first and second master station terminals; a second power source that applies a voltage so that the parent terminal becomes positive; a power source selection unit that selects the first and second power sources; comprising a master station signal transmitting means for changing the current flowing between the station terminals, and a master station signal receiving means for detecting a change in the current flowing between the first and second master station terminals by the second power supply, The signal transmitting/receiving section of the slave station is connected to a first slave station terminal located on the first master station terminal side, a second slave station terminal located on the second master station terminal side, and the first slave station terminal and the second slave station terminal located on the second master station terminal side. a series circuit of a light emitting diode and a first diode of a signal receiving photocoupler connected between second slave station terminals so that the direction from the first slave station terminal to the second slave station terminal is the forward direction; and a phototransistor of the signal receiving photocoupler that detects a change in current flowing through the light emitting diode of the signal receiving photocoupler, and a connection between the first and second slave station terminals from the second slave station terminal to the first slave station terminal. A series circuit of a phototransistor and a second diode of a signal transmission photocoupler connected so that the direction toward the slave station terminal is the forward direction, and a signal transmission photocoupler that changes the current flowing through the phototransistor of the signal transmission photocoupler. Since it is configured with two light emitting diodes, it is a simple and inexpensive configuration that requires only arranging two communication lines and inserting the signal transmitting/receiving sections of multiple slave stations in the middle. This has the effect of allowing two-way communication between the two.

[Brief explanation of drawings]

The drawing is a circuit diagram of an embodiment of this invention. DESCRIPTION OF SYMBOLS 1... Signal transmitting/receiving section of master station, 2, 3... Signal transmitting/receiving section of slave station, 4... Communication line, 1a, 1b... Master station terminal, 2a, 2b, 3a, 3b... Slave station terminal,
6...Photocoupler (for reliable transmission, power supply selection),
8...Power supply (first), 10...Photocoupler (for power supply selection), 13...Power supply (second), 14, 15...
Photocoupler (for signal reception), 14a, 15a...
Light emitting diode, 14b, 15b...Phototransistor, 16, 17...Photocoupler (for signal transmission), 16a, 17a...Light emitting diode, 16
b, 17b...phototransistor, 18-21...
…diode.

Claims (1)

[Claims for Utility Model Registration] A signal transmitting/receiving section of a master station, two communication lines whose starting ends are connected to the signal transmitting/receiving section of the master station and whose terminal ends are short-circuited, and a series connection between the two communication lines. signal transmitting and receiving units of a plurality of slave stations inserted into the base station, and first and second master station terminals connecting the signal transmitting and receiving units of the master station to starting ends of the two communication lines;
a first power supply that applies a voltage between the first and second master station terminals so that the first master station terminal becomes positive; and a first power supply that applies a voltage between the first and second master station terminals; a second electrode for applying a voltage so that the parent station terminal becomes a positive electrode; a power source selection means for selecting the first and second power sources; comprising a master station signal transmitting means for changing the current flowing between the station terminals, and a master station signal receiving means for detecting a change in the current flowing between the first and second master station terminals by the second power supply, The signal transmitting/receiving section of the slave station is connected to a first slave station terminal located on the first master station terminal side, a second slave station terminal located on the second master station terminal side, and the first slave station terminal and the second slave station terminal located on the second master station terminal side. a series circuit of a light emitting diode and a first diode of a signal receiving photocoupler connected between second slave station terminals so that the direction from the first slave station terminal to the second slave station terminal is the forward direction; and a phototransistor of the signal receiving photocoupler that detects a change in current flowing through the light emitting diode of the signal receiving photocoupler, and a connection between the first and second slave station terminals from the second slave station terminal to the first slave station terminal. A series circuit of a phototransistor and a second diode of a signal transmission photocoupler connected so that the direction toward the slave station terminal is the forward direction, and a signal transmission photocoupler that changes the current flowing through the phototransistor of the signal transmission photocoupler. A signal transmission device consisting of a light emitting diode.