JPS639416B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a communication method for a remote monitoring system, and particularly to a communication method during a power outage.

Conventionally, the communication method of a remote monitoring system that connects n terminal devices (multiple) to one center device is as shown in Fig. 1, between the center device C and the terminal device A.
Data is transmitted using the 1st, 2nd, and 3rd wires L ₁ , L ₂ , and E, and the 1st wire
A communication current was passed between L ₁ and the third line E, and between the second line L ₂ and the third line E, so that the currents in the third line E were in opposite directions. Therefore, as the number of terminal devices that can be monitored increases, the current capacity of the communication current supply power supply device on the center device C side, the external dimensions and weight of the device, the battery capacity for backup during power outages, etc. have increased. . For this reason, if the external dimensions and weight of the power supply device are kept constant, it is necessary to reduce the number of terminal devices that can be monitored in the center device or to shorten the time during which data can be transmitted during a power outage.

The present invention eliminates these drawbacks of the conventional devices, and makes it possible to extend the time during which data can be transmitted between the center device and the terminal device by stopping the supply of communication current except when transmitting data during a power outage. It is something.

According to the present invention, data is transmitted between the center device and the terminal devices using the first, second, and third lines, and during normal times, data is transmitted between the first line and the third line, and between the second line and the third line.
A communication current is always passed between the lines so that the current in the third line is in the opposite direction, and during data transmission, the communication current between the first line and the third line and between the second line and the third line is made into a double current. During power outage, communication current is supplied between the first and third lines and between the second and third lines only when data is being sent and received, and the supply of communication current is stopped after data transmission and reception is completed. A communication method for a remote monitoring system is obtained.

Next, embodiments of the present invention will be described with reference to the drawings. FIG. 2 is a block diagram of an embodiment of the present invention, in which a center device C and a terminal device A are connected to a first line L ₁ ,
This shows a system in which three wires, a second line L ₂ and a third line E, are used to transmit and receive data. The center device C has a receiving relay R ₁ between the first line L ₁ and the third line E.
and a data detection diode _D1 are connected, and between the second line _L2 and the third line E, power supplies _V1 and _V2 for data transmission are connected. _V1 and _V2
is a direct current power supply with opposite polarity, positive and negative, for sending double current data.When commercial AC power is supplied, it is a rectified DC power supply, and when the commercial AC power is cut off, it is used as a storage battery ( (not shown).

Furthermore, the second line L ₂ has a contact t ₁ of a data transmission relay T ₁ that sends double-current data by switching the power supplies V ₁ and V ₂ in series, and a contact of a power supply stop relay P ₁ that stops the communication current in the event of a power outage. p ₁ is connected. The internal configuration of the center device C consists of a data reception section 1, a data transmission section 2, a data identification conversion section 3, a display section 4, a data input section 5, and a power outage detection section 6. The on/off of contact r ₁ of R ₁ is used as data input, and data transmitter 2 drives data sending relay T ₁ to switch contact t ₁ . The data recognition converter 3 includes the data receiver 1,
It recognizes data from the data input section 5 and power outage detection section 6 and performs various controls.

The configuration of the terminal device A is similar to that of the center device C, and includes a data receiving section 1', a data transmitting section 2', a data identification converting section 3', a data input section 5', and a power outage detecting section 6'. . The data receiving section 1' is a contact point of a receiving relay _R1 ' connected between the first line _L1 and the third line E.
Data is received by opening and closing r ₁ ', and data transmitting section 2' transmits data by opening and closing contact t ₁ ' of data sending relay T ₁ '. Data transmission to the center device is performed by switching and connecting the data transmission relay contact t ₁ ′ to the data transmission power supply V ₁ ′, V ₂ ′ in the same way as data transmission from the center device to the terminal device. be exposed. P ₁ ' is a power supply stop relay, which is driven by the data identification converter 3' to turn on and off the contact p ₁ '.

Under normal conditions on the center device C side, the power supply stop relay P ₁ is driven, its contact p ₁ is on (the state indicated by the dotted line in the figure), and the contact t ₁ of the data transmission relay T ₁ is in the data transmission state. Connected to the power supply _V1 side. In addition, in normal times, terminal device A also has contact p ₁ ′ of power supply stop relay P ₁ ′ turned on, and contact t ₁ ′ of data sending relay T ₁ ′ turns on power supply power supply for data sending.
Connect to V ₁ ′ side. Therefore, under normal conditions, each contact point is in the state shown by the dotted line in the figure, and the first line _L1 and the third
A closed loop is formed between the line E, the second line _L2 , and the third line E, and currents in opposite directions flow through the third line.

During data transmission, center device C keeps contact p ₁ on and sends double current data from the positive and negative power supplies to second wire L _{2 and} third wire E by turning on and off contact t ₁ of data sending relay T 1. Send via. Similarly, terminal device A also closes contact p ₁ ′ with contact p 1 ′ turned on.
Double current data is sent via the first line _L1 and the third line E by turning on and off _t1' .

When the center device C receives data from the terminal side via the first line _L1 and the third line E, the reception relay contact
Since r ₁ turns on (grounded) or off (open) according to the received data and performs the reception operation, the receiving section 1 detects the data and converts it to the received data identification conversion section 3.
It is displayed on the display section 4 via the. At this time, when it is necessary to respond to the received data, the received data identification converting section 3 operates the data sending relay T1 via the data transmitting section ₂ , and sends the response data to the terminal side.

Next, the operation during a power outage will be explained.

When a power outage occurs on the side of the center device C, the power outage detection section 6 detects the power outage, and based on the detection, the data identification conversion section 3 controls the data sending section 2, thereby operating the relay _T1 . , causes the terminal device A side to send out a power outage detection signal.

When the data recognition converter 3 of the center device confirms that the power failure detection signal has been definitely received on the terminal A side using the data from the data receiver 1, it turns off the power supply stop relay P ₁ on the center device C side. year,
The contact _p1 is disconnected and the second line _L2 is disconnected to prevent communication current from flowing. On the other hand, on the terminal side, similarly, the power supply stop relay P ₁ ' is duplicated to disconnect the first line L ₁ so that no communication current flows. During a power outage, the power source for the center equipment is switched to the backup storage battery.

If it is necessary to send data during a power outage, the data recognition converter 3 operates using the backup storage battery as a power source, operates the power supply stop relay _P1 , turns on contact _P1 , and also operates the data transmitter 2 to send out a data sending request signal from the contact _t1 of the data sending relay _T1 . On the other party's side, that is, in the terminal device A, the data receiving unit ₁ ' receives the data transmission request signal via the data receiving relay R'1,
The data recognition converter 3' operates the power supply stop relay _P'1 to turn on the contact _p1 . Contact points as above
When p ₁ and p ₁ ' are turned on sequentially, data is transmitted and received between the center and the terminal side, and when the data transmission and reception is completed, the power supply stop relay P ₁ , Turn off P ₁ ′,
The communication currents of the first line L ₁ and the second line L ₂ are turned off.

Although FIG. 2 shows a case where only a series circuit consisting of unidirectional diodes D ₁ and D ₁ ' and relays R ₁ and R ₁ ' is provided in the data transmission line L ₁ ,
By adding a series circuit of diodes and relays connected in the opposite direction in parallel to this series circuit, and supplying the received signal to the data receiving sections 1 and 1' through the contacts of these relays, double current can be prevented. It should be obvious.

The above is the operation when there is a power outage on the center device, but the same operation occurs when there is a power outage on the terminal device side.
That is, when a power outage is detected by the power outage detection unit 6',
A power failure detection signal is sent to the center device, and contact p ₁ ,
p ₁ ′ is turned off. Also, when sending data, a data sending request signal is sent to the center side, which turns on contacts p ₁ and p ₁ ′ to perform data sending and receiving, and when data sending and receiving is completed, contacts p ₁ and p ₁ ′ is turned off again.

By doing this, it is possible to obtain the same effect as in the past when communication current is constantly flowing during a power outage.Furthermore, since there is no need to constantly supply communication current during a power outage, the capacity of the storage battery is small, and the power outage is interrupted. The available data transmission time can be extended.

As described above, the present invention has the effect of reducing the battery capacity by stopping the supply of communication current during a power outage, thereby extending the data transmission possible time during a power outage.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the direction of line current between conventional devices, and FIG. 2 is a block diagram of an embodiment of the present invention. _L1 ...Data transmission line from the terminal side to the center side, _L2 ...Data transmission line from the center side to the terminal side, E...Common line for the _L1 and _L2 lines, P ₁ , P ₁ ′...Power supply stop relay, T ₁ ,
T ₁ ′... Relay for data transmission, R ₁ , R ₁ ′... Relay for data reception, D ₁ ... Diode for data detection, V ₁ , V ₁ ' and V ₂ , V ₂ '... For data transmission Power supply, 1, 1'...data receiving section, 2, 2'...data transmitting section, 3, 3'...data identification conversion section, 4...
...Display section, 5, 5'... Data input section, 6, 6'...
...Power failure detection unit.

Claims (1)

[Claims] 1 The first device connected between the center device and the terminal device,
In a remote monitoring system that transmits data using the second and third wires, during normal times, closed loops are formed between the first and third wires and between the second and third wires, and the communication current is transferred to the third wire. The currents in the lines are always flowing in opposite directions, and when transmitting data, the communication current between the first line and the third line and between the second line and the third line is made into a double current to transmit and receive data, In the event of a power outage, a closed loop is formed between the 1st and 3rd lines and between the 2nd and 3rd lines only when data is being transmitted/received, and communication current is supplied, and the communication current supply is stopped after data transmission/reception is completed. A communication method for a remote monitoring system that is characterized by: