JPH09147274A - Monitoring device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To decrease the number of signal lines and also to reduce the cost of parts needed for transmission of signals when the signals are transmitted in a long distance between a main device and sensors respectively. SOLUTION: A main device 1 is provided with the transistors TR Q1 to Q2, and the series connection is secured between the TR Q3 and Q4 and also between the TR Q3 and Q4 respectively. Then a common current loop is formed by a pair of signal lines which secure the connection between the connection point of both TR Q1 and Q2 and that of both TR Q3 and Q4. The TR Q2 and Q3 are turned on and off respectively to send the signals to the sensors. At the same time, the TR Q1 and Q4 are turned on to receive the signals via a photocoupler PC1. On the other hand, the sensors receive the signals via the photocouplers PC2 and PC4 and the photocouplers PC3 and PC5 are driven to transmit the signals. As a result, the sure transmission of signals is attained in a simple constitution and in a least number of signal lines.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a monitoring device for monitoring the detection status of each sensor.

[0002]

2. Description of the Related Art A monitoring device of this kind for monitoring the states of a plurality of sensors comprises a main device and each sensor.
Here, the main device has a plurality of ports, and the main device and each sensor are connected by a so-called star wiring in which each sensor is individually connected to each port of the main device. In this case, the main device transmits data to each sensor through each line and monitors the detection status of each sensor.

[0003]

However, in the case of star wiring, the number of ports of the main unit and the number of outgoing lines from the main unit are required for the number of sensors, and the main unit becomes large and the wiring work becomes complicated. There is a problem of inviting. In addition, there is a problem that when wiring is performed using existing piping in a building, the capacity of the piping is insufficient and wiring becomes impossible.

Therefore, it is conceivable to reduce the number of wires between the main device and each sensor by bus wiring or loop wiring without performing star wiring. However, in this case, each sensor is mainly connected at the time of data transmission. Since the identification code for identifying the sensor must be added to the data transmitted to the device side, and therefore the number of data transmitted from each sensor increases, the transmission rate increases when the number of accommodated sensors increases. Will need to be fast. However, in the case of long-distance transmission where the distance between the main device and each sensor is several hundred meters, it is necessary to transmit / receive data using a modem or the like in order to transmit / receive data at high speed. There is a problem of rising. Therefore, it is an object of the present invention to reduce the number of signal lines and to reduce the cost of parts for data transmission when signals are transmitted over a long distance between a main device and each sensor.

[0005]

In order to solve such a problem, the present invention forms a first current loop consisting of a pair of common signal lines between a main device and each sensor. The signal is transmitted depending on the presence / absence of current in the current loop. Therefore, since the signal can be transmitted by the first current loop including the pair of signal lines, the signal can be transmitted with the minimum number of signal lines when performing long-distance transmission. Further, the main device transmits a signal to each sensor by energizing and de-energizing the first current loop, while being connected to each sensor in parallel with the first current loop and having a polarity opposite to the current polarity of the first current loop. A second current loop having a current polarity of 1 is provided, and each sensor performs energization and de-energization of the second current loop when the first current loop is de-energized after the signal is transmitted from the main device. The signal is transmitted to the main device by energizing and de-energizing so that the current polarity of the current loop 1 is opposite to the transmitting direction from the main device side. Therefore, in each sensor, the current polarity of the first current loop is different at the time of signal transmission and at the time of signal reception, so when other sensors are transmitting data to the main device 1, this transmission data sneak Therefore, the erroneous recognition of the wraparound data can be avoided in advance, so that the data format can be simplified and the data can be transmitted with a reduced number of data. Therefore,
It is not necessary to increase the data transmission speed, and long-distance transmission can be made possible with a simple and inexpensive structure.

Further, the main device is provided with first to fourth switching elements, the first and second switching elements are connected in series, and the third and fourth switching elements are connected in series to form the first and fourth switching elements. A first current loop is formed by connecting a first connection point, which is a connection point between the second switching elements, and a second connection point, which is a connection point between the third and fourth switching elements, to form a first current loop. A signal is transmitted to each sensor by turning off the first and fourth switching elements and turning on and off the second and third switching elements, and a signal is transmitted between the second connection point and the fourth switching element. The first photocoupler is provided, the signals of the respective sensors are received from the output of the first photocoupler by turning off the second and third switching elements and turning on the first and fourth switching elements. The sensor is provided with a second photocoupler for detecting the presence / absence of a current in the first current loop, the signal from the main device is received based on the output of the second photocoupler, and the second current loop is provided with a third photocoupler. The photo coupler of
A signal is transmitted to the main device by the output of the third photo coupler. As a result, it is possible to reliably transmit a signal with a simple configuration and a minimum number of signal lines, and it is possible to operate the main device and each sensor with different power supply systems.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 2 is a block diagram showing the configuration of the monitoring device according to the present invention. The monitoring device includes the main device 1 and a plurality of sensors 31 to 3n connected to the main device 1. Here, the main device 1 accommodates a telephone line (subscribed line) and can also be connected to this telephone, and an incoming call detection circuit 11 and a loop for detecting the presence or absence of DC loop closure of the line by this telephone Detection circuit 12, switching relay 13 for switching between the line and the telephone, dial transmission circuit 1
4, a hybrid circuit 15, an I / F unit 17 that is a transmission interface with each sensor, a control unit 18 that controls the above units, and the like.

The control unit 18 includes a CPU 18A and a PI.
O section 18B, data bus buffer 18C, address decoder 18D, address latch 18E and reset section 18
An SRAM 19 and a clock I which are composed of F and store data
C20 is connected. On the other hand, each of the sensors 31 to 3n is connected to the main device 1 via the connecting portion 21 and the pair of signal lines 22. Each of the sensors 31 to 3n has a connection unit 31, an I / F unit that is an interface with the main device 1, and
It is composed of a CPU 33 and an ID setting unit 34 for setting an identification code of the sensor itself. CPU 33 of the sensor
When receiving a command signal from the main device, the device detects the state of the door lock of each door, such as the opening and closing of the door of each door, through the contact portion 40 and returns it to the main device 1 as a response signal. In this case, the main unit 1 reports the content of the response to the center side (not shown) via the subscription line.

Next, FIG. 1 is a circuit diagram showing a main structure of the present invention. The I / F section 17 of the main device 1 and the I / F of the sensor 3 are shown.
3 illustrates each configuration of the unit 32. In FIG. 1, the I / F unit 17 of the main device 1 includes a transistor Q connected in series.
1, Q2, transistors Q3, Q4, buffers IC1, IC, which are similarly connected in series via the photocoupler PC1.
2 and resistors R1 to R12. Here, the main device 1
And one of the pair of signal lines 22 connecting the respective sensors to each other, one signal line 221 is commonly connected to each sensor from the connection point of the transistors Q1 and Q2 through the resistor R5, and the other signal line 222 is Transistor Q3 and photo coupler P
It is commonly connected to each sensor through a resistor R12 from a connection point with C1.

In each sensor, such signal lines 221 and 2
A resistor and a photocoupler are connected in series with 22. That is, for example, in the case of the sensor 31 the resistor R13 and the photocoupler PC2 are connected in series, and in the case of the sensor 3n the resistor R17 and the photocoupler PC4 are connected in series. Then, when the transistors Q2 and Q3 are turned on in order to transmit a signal to each sensor on the main device 1 side, a current flows from the transistor Q3 to the signal line 222, and this current is, for example, the resistor R13 in the sensor 31 and the photocoupler PC2.
To reach the signal line 221 and further to the transistor Q2
A current loop (first current loop) flowing into the is formed. The current-carrying state of the signal line 22 is detected by the sensor 31 as a current flowing through the photocoupler PC2 and transmitted to the CPU 33 via the buffer IC3.

In the sensor 3n, similarly,
The current flowing through the signal line 222 is the resistance R1 in the sensor 3n.
7. Reach the signal line 221 through the photo coupler PC4,
It flows into the transistor Q2 of the main device 1. Then, the sensor 3n detects the current flowing through the photocoupler PC4 and transmits it to the CPU 33 via the buffer IC5. In this way, signals are transmitted from the main device 1 in a so-called broadcast format in which a transmission signal is simultaneously given to each sensor. The signal current in this case flows from the signal line 222 to the signal line 221 as described above.

In response to such signal transmission from the main device 1 side, signals are transmitted from each sensor to the main device 1 side as follows. That is, in the sensor 31 for example, first, the photocoupler PC3, the resistor R14 and the diode D1 are connected in parallel to the photocoupler PC2 and the resistor R13.
To form a current loop. Then, the signal is transmitted to the main device 1 side by controlling the buffer IC 4 to turn on / off the photocoupler PC3. In this case, since the transistors Q1 and Q4 on the main device 1 side are both turned on, the signal line 2 is passed from the transistor Q1 through the resistor R5.
The current flowing in 21 is sent to the signal line 222 through the photocoupler PC3, the resistor R14 and the diode D1 which are the second current loop in the sensor 31, and the resistors R12, R10 in the main unit 1 and the photocoupler. It is made to flow out to the transistor Q4 via PC1.

Similarly, in the sensor 3n, when the photocoupler PC5 is turned on / off, the current from the main device 1 side is sent through the signal line 221 through the photocoupler PC5, the resistor R18 and the diode D2 in the sensor 3n. The signal is output to the line 222, and is output to the transistor Q4 through the resistors R12 and R10 in the main device 1 and the photocoupler PC1. In this way, when transmitting a signal from each sensor to the main device 1, the direction opposite to that when transmitting a signal from the main device 1 to the sensor (that is, from the signal line 221 to the signal line 2) is used.
Electric current flows in the 2 2 direction). Therefore, it is possible to prevent the transmission signal from the sensor transmitting the signal from wrapping around the sensor that does not transmit the signal.

When transmitting a signal from each sensor to the main device 1, each sensor does not transmit a signal at the same time, but one of the sensors transmits. That is, when transmitting a signal from the main device 1 to the sensor, the main device 1 transmits the sensor identification code. Then, each sensor receives this transmission signal, refers to the identification code set by the ID setting unit 34, and only the sensor having the corresponding identification code returns a signal to the main device 1 side.

Next, the operation of the main part of the present invention will be described in more detail with reference to FIG. When there is a sensor whose state is desired to be detected, the main device simultaneously transmits the identification code of the corresponding sensor and the corresponding command to each sensor as described above. That is, in this case, first, the data "1"("H" level) is output as the output from the CPU 18A.
Then, the transistor Q1 is turned off and the transistor Q2 is turned on. Further, at this time, since the output of the buffer IC2 becomes "L" level, the transistor Q3 is turned on,
The transistor Q4 is turned off.

As a result, a current flows through the signal line 222 through the turned-on transistor Q3 and the resistor R12, and a resistor and a photocoupler in each sensor (for example, the resistor R13 in the case of the sensor 31 and the photocoupler PC2 and the sensor 3n). Flows through the resistor R17 and the photocoupler PC4) to the signal line 221, and further flows through the resistor R5 in the main unit 1 and the turned-on transistor Q2 to the ground.
As a result, for example, in the sensors 31 and 3n, the photocouplers PC2 and PC4 are turned on, and the buffer ICs are turned on.
3, data "1" is transmitted to each CPU 33 via IC5.

Next, when the CPU 18A of the main device 1 transmits data "0"("L" level), the transistor Q1 is turned on and the transistor Q2 is turned off. At this time, since the output of the buffer IC2 is at the "H" level, the transistor Q3 is off and the transistor Q4 is on. In this case, since no current flows through the signal line 22, the photocoupler PC is connected to each of the sensors 31 and 3n.
2 and PC4 are turned off, so that data “0” is sent to each CPU 33 via the buffer IC3 and IC5.
Is transmitted. In this way, data is transmitted to each sensor depending on the presence / absence of current in the signal line 22.

After the data is transmitted from the CPU 18A of the main unit 1 to each sensor, the CPU 18A sets each of the transistors Q1 to Q4 to the same state as when transmitting the above-mentioned data "0" and the sensor side. Receive data from. That is, the transistors Q1 and Q4 are turned on and the transistors Q2 and Q3 are turned off. Here, the main device 1
If the sensor that matches the identification code transmitted when the command is transmitted from the side is the sensor 31 for example, the CPU 33 of the sensor 31 detects the condition of the contact portion 40 and outputs this contact data to the buffer IC 4.

In this case, the data "1" is sent from the CPU 33.
(“H” level) is output, the buffer IC
Since the output of 4 becomes "L" level, the photocoupler PC3 is turned on. Then transistor Q1 → resistor R
5 → signal line 221 → photo coupler PC3 → resistor R14 →
Diode D1 → signal line 222 → resistor R12 → resistor R1
A current flows in the direction of 0 → photo coupler PC1 → transistor Q4. As a result, the CPU 18A of the main device 1 detects the current flowing through the photocoupler PC1 as an “H” level signal via the buffer IC1. Therefore, the output data "1" of the sensor 31 can be received as the data "1".

When the sensor 31 outputs the data "0", the photocoupler PC3 in the sensor 31 does not turn on, so that no current flows through the signal line 22. Therefore, the CPU 18A in the main unit 1 buffers. Data "0" is received via IC1. In this way, data transmission is performed between the main device 1 and each sensor. In this case, the main device side and each sensor side may always set the data output port to the “L” level except when the data itself is transmitted “1”. Bidirectional transmission can be realized without being aware of switching,
It is possible to simplify the control and eliminate the need for a port for switching between transmission and reception.

When it is not necessary to supply power to each sensor from the main device 1 side as in this example (that is, each sensor is operated by a battery or the like), a photo coupler is used to minimize the power consumption. Signals can be transmitted and received by the two signal lines 221 and 222, and since these signal lines 221 and 222 are not the power line and the ground line, respectively, the influence of common mode noise on the signal transmission can be reduced. . Further, since the main device 1 and each sensor are electrically insulated by the photo coupler, the main device 1 and each sensor can be operated by different power supply systems.

Further, when another sensor is transmitting data to the main device 1, this data wraparound is prevented, so that erroneous recognition of the wraparound data can be avoided in advance. It can be simplified and transmitted with a small number of data. As a result, there is no need to increase the data transmission speed, and therefore long-distance transmission can be made possible with a simple and inexpensive structure.

[0023]

As described above, according to the present invention, a first current loop consisting of a pair of common signal lines is formed between the main device and each sensor, and the presence or absence of current in the first current loop is formed. Since the signal is transmitted by the method, the signal can be transmitted with the minimum number of signal lines when the long distance transmission is performed. Also,
The main device sends a signal to each sensor by energizing and de-energizing the first current loop, while a current connected to each sensor in parallel with the first current loop and having a polarity opposite to the current polarity of the first current loop. A second current loop having a polarity is provided, and each sensor energizes and de-energizes the second current loop when the first current loop is de-energized to energize and de-energize the first current loop in the opposite polarity. Since the signal is sent to the main device by doing so, in each sensor, the current polarity of the first current loop is different between when the signal is sent and when the signal is received. During transmission, the wraparound of the transmitted data is prevented, and therefore erroneous recognition of the wraparound data can be avoided in advance, so that the data format can be simplified and the number of data can be reduced. Therefore, it is not necessary to increase the data transmission rate, and long-distance transmission can be realized with a simple and inexpensive structure.

Further, the main device is provided with first to fourth switching elements, the first and second switching elements are connected in series, and the third and fourth switching elements are connected in series to provide the first and fourth switching elements. The first connection point, which is a connection point between the second switching elements, and the second connection point, which is a connection point between the third and fourth switching elements, are connected to each other to form the first connection point.
Forming a current loop, turning off the first and fourth switching elements and turning on the second and third switching elements.
When turned off, a signal is transmitted to each sensor, and a first photocoupler is provided between the second connection point and the fourth switching element to turn off the second and third switching elements and Also, by turning on the fourth switching element, the signal of each sensor is received from the output of the first photocoupler, while each sensor is provided with a second photocoupler for detecting the presence or absence of current in the first current loop. A third photocoupler is provided in the second current loop while receiving a signal from the main device based on the output of the second photocoupler, and a signal is transmitted to the main device by the output of the third photocoupler. With this configuration, it is possible to reliably transmit a signal with a simple structure and a minimum number of signal lines, and it is possible to operate the main device and each sensor with different power supply systems.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a main configuration of a monitoring device according to the present invention.

FIG. 2 is a block diagram showing a schematic configuration of a monitoring device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Main device, 31-3n ... Sensor, 18 ... Control part, 18
A, 33 ... CPU, 17, 32 ... I / F section, 22, 22
1, 222 ... Signal line, 34 ... ID setting section, 40 ... Contact section, Q1-Q4 ... Transistor, PC1-PC5 ... Photocoupler, D1, D2 ... Diode, IC1-IC6 ...
Buffer, R1 to R20 ... Resistors.

Claims (3)

[Claims] 1. A monitoring device comprising a main device and a plurality of sensors, wherein the main device monitors the detection status of each sensor by transmitting a signal to each sensor. A monitoring device, characterized in that a first current loop formed of the signal line is formed, and a signal is transmitted depending on the presence or absence of a current in the first current loop. 2. The main unit according to claim 1, wherein the main device transmits a signal to each sensor by energizing and de-energizing the first current loop, while each sensor is connected in parallel to the first current loop and includes a first current loop. A second current loop having a current polarity opposite to the current polarity of the current loop is provided, and each sensor has a first current loop after the signal from the main device is transmitted.
By energizing and de-energizing the second current loop when the current loop is de-energized, energization and de-energization are performed so that the current polarity of the first current loop is opposite to the transmission direction from the main device side. The monitoring device is characterized by transmitting a signal to the main device. 3. The main device according to claim 2, wherein the main device is provided with first to fourth switching elements,
The first and second switching elements are connected in series, the third and fourth switching elements are connected in series, and the first connection point, which is a connection point between the first and second switching elements, and the third and fourth A second connection point, which is a connection point between the fourth switching elements, is connected to form the first current loop, and the first and fourth switching elements are turned off to generate the second switching element.
A signal is transmitted to each sensor by turning on and off the third switching element, and a first photocoupler is provided between the second connection point and the fourth switching element, and the second and third switching elements are provided. The signal from each sensor is received on the basis of the output of the first photocoupler by turning off the switching elements of the first and fourth switching elements and turning on the first and fourth switching elements. A second photocoupler for detecting the presence or absence of current is received, a signal from the main device is received based on the output of the second photocoupler, and a third photocoupler is provided in the second current loop. A monitoring device, wherein a signal is transmitted to the main device by the output of the photocoupler.