JPH048808B2 - - Google Patents

Description

[Detailed Description of the Invention] (1) Technical Field of the Invention The present invention provides a power cutoff method, in particular, a system in which the main body control unit and the line control unit independently cut off the power after obtaining the right to use the line. This relates to the power cutoff method.

(2) Problems with the prior art In general, when a terminal device needs to turn off its own power, it acquires the right to use the line without immediately cutting off the power in order to prevent noise from being added to other terminal devices. Request signal RS (request to send)
is sent onto the line from the line control unit, requests the right to use the line from other terminal devices, and after acquiring the right to use the line, the power is turned off. A conventional example of a control circuit that executes such power cutoff is shown in FIG. 1, for example. This control circuit includes a main body control section 1 built into the terminal device, a line control section 2 for controlling the connection state between the terminal device itself and the line, and a circuit control section 2 for turning on and off the power of the terminal device. It has a power supply section 3. The line control unit 2 includes an RS synthesis circuit 4 that sends an RS signal requesting the right to use the line to the line or center, and an AND gate 5 that receives a line use permission signal CS (clear to send) from the center. On the other hand, a power cutoff circuit 6 is built into the power supply section 3 . When the operator turns off the power cutoff switch 7, the signal is transmitted to the main body control section 1, and the main body control section 1 sends a line acquisition request signal S1 to the line control section 2.
That is, it is output to the RS synthesis circuit 4. The RS synthesis circuit 4 receives a line acquisition request from the main body control unit 1.
An RS composite signal, ie, a line usage right request signal RS, is sent to the center. As a result, a line use permission signal CS is sent from the center, this line use permission signal CS is sent to the line control section 2 of the terminal device through the line, and is input to the AND gate 5 in the line control section 2. The line acquisition request signal S1 output from the main body control unit 1 is also input to the AND gate 5, and the line acquisition request signal S1 is ANDed with the line use permission signal CS and sent to the main body control unit 1. Output S2. Upon receiving the line acquisition signal S2, the main body control section 1 outputs a disconnection signal S3 to the power supply section 3, which causes the power disconnection circuit 6 to operate and disconnect the power to the terminal device. Such a power-off operation of a terminal device is performed according to the timing diagram shown in FIG. The acquisition signal S2 is sent to the main body control section 1, and after a certain period of time has elapsed, the main body control section 1 outputs a disconnection signal S3. As a result, when a terminal device leaves the line, noise is introduced onto the line due to the relay switching operation, and if another terminal device is communicating using this line, this power disconnection causes noise to be transferred onto the line. Preventing interference. In addition, to protect other terminal devices when the power is turned off,
For example, if a terminal device issues a line acquisition request in order to turn off the power, and the line use permission signal CS is not received from the center within a certain period of time, the power is automatically turned off. There is.

However, in such a conventional power-off method of a terminal device, even if the line use permission signal CS is input from the center through the line, the power-off signal S3 to the power supply section 3 is not transmitted by the main body control section 1. If there is some kind of abnormality in the main unit control unit 1 and it does not operate normally, the terminal device cannot be powered off even though the center has given permission to use the line, and other devices There was a problem with terminal equipment in which the line could not be used for any length of time.

In other words, the protocol used in this terminal device is, for example, when each terminal device is connected to the center in a daisy chain, and when it is desired to turn off the power to a certain terminal device, this terminal device has the right to use the line as explained above. After securing and prohibiting communication between other terminal devices and the center, the power is turned off. Then, when the power to this terminal device is cut off, the line usage right request signal RS issued from this terminal device is turned off, and communication between other terminals and the center becomes possible. However, if the power to this terminal device is not turned off, the line usage right request signal RS issued from it will not turn off and this terminal device will continue to have the line usage right, so other terminal devices will not be able to communicate with the center. Unable to do so, the entire line was locked up.

(3) Purpose of the invention The present invention has been made by focusing on the above-mentioned conventional problems, and its purpose is to:
It is an object of the present invention to provide a power cutoff method in which a main body control section and a line control section can operate independently to cut off the power, thereby ensuring reliable operation of disconnecting a terminal device from the line.

(4) Structure of the Invention In order to achieve the above object, the present invention connects a plurality of terminal devices having a main body control section and a line control section to one line, and when a certain terminal leaves the line, the terminal device In a power cutoff method in which the power is cut off by the operation of the main unit control unit after obtaining the right to use the line, even if the disconnection signal is not issued from the main unit control unit after obtaining the line use right, the line control unit The gist of this is that the power can be turned off by command. Commands from the line control unit are issued by outputting a power cut signal from the line control unit to the power supply unit.
This disconnection signal can be output in various cases depending on the abnormal state of the main body control section. For example, although a line use permission signal was sent from the center to the terminal device through the line, and a line acquisition signal was output from the line control unit to the main unit control unit based on this, the main unit control unit was not able to acquire the line due to an abnormality. In cases where confirmation and disconnection signals cannot be issued, or even though a confirmation signal indicating that the line acquisition signal has been received by the main unit control unit has been issued to the line control unit,
There may be a case where the disconnection signal is not issued due to some abnormality in the main body control section. The power cutoff method of the present invention can also be applied to such various abnormalities in the main body control section.

(5) Embodiments of the Invention FIGS. 3 and 4 are diagrams showing embodiments of a control circuit for carrying out the power cutoff method of the present invention.
This control circuit includes a main body control section 1, a line control section 2 having an RS synthesis circuit 4 and an AND gate 5,
The main component is a power supply section 3 having a power cutoff circuit 6. The line control section 2 further includes the main body control section 1.
an OR gate 8 which calculates the logical sum of a line acquisition request signal S1 for power cutoff from the OFF switch 7 and a line acquisition request signal S4 for power cutoff outputted by turning off the power cutoff switch 7; A timer 9 that is activated when the output line acquisition signal S2 is input, and an AND gate that performs a logical product between the output signal from the timer 9 and the line acquisition confirmation signal S5 from the main body control unit 1. 10 is incorporated. Further, the power supply unit 3 includes an OR gate 12 that calculates the logical sum between the output signal from the AND gate 10, that is, the disconnection signal S7, and the disconnection signal S3 from the main body control unit 1.

In a control circuit having such a configuration, when the operator turns off the power cutoff switch 7, the main body control section 1 outputs a line acquisition request signal S1, and the power cutoff switch 7 also outputs a line acquisition request signal S.
4 is output, and both are input to the OR gate 8 in the line control section 2. The OR gate 8 outputs a signal to the RS synthesis circuit 4 indicating that the power cutoff switch 7 is turned off, and the RS synthesis circuit 4 generates a line usage right request signal RS. sent to the center through On the other hand,
The output from the OR gate 8 is also sent to the AND gate 5 in the line control section 2. As a result, there is an abnormality in the main body control unit 1, and the line acquisition request signal S1
Even if the line acquisition request signal S4 from the power cut-off switch 7 is not output, the line acquisition request signal S4 is sent to the line control unit 2, and a predetermined line usage right request signal RS is sent on the line, so that the line acquisition request signal S4 from the power cut-off switch 7 is sent to the line. There is no risk of interference due to the power being cut off. Next, the line use permission signal CS from the center is sent to the AND gate 5 in the line control unit 2 as a line acquisition request signal S1 or S.
4 and the AND gate 5 outputs the line acquisition signal S2 to the main body control unit 1 and the timer 9.
sent to. Next, a line acquisition confirmation signal S5 is sent from the main body control section 1, and this line acquisition confirmation signal S5 is input to the AND gate 10 in the line control section 2 through the inverter 11. On the other hand, timer 9
starts operating upon receiving the input of the line acquisition signal S2, and when a predetermined time elapses, the AND gate 10
It emits an output signal S6 towards the target. Main body control section 1
After issuing the line acquisition confirmation signal S5, it issues a disconnection signal S3, and this disconnection signal S3 is input to the OR gate 12 built into the power supply section 3. On the other hand, the output signal from the AND gate 10 is input to the OR gate 12 as a disconnection signal S7. Then, the OR gate 12 performs a logical sum between the disconnection signal S3 and the disconnection signal S7, and its output is sent to the power supply switching circuit 6 to cut off the power to the terminal device.

Here, if we look at the case where the main body control section 1 in the terminal device is working normally, this main body control section 1
After receiving the line acquisition signal S2, it issues a line acquisition confirmation signal S5 to the AND gate 10. Since this line acquisition confirmation signal S5 is inverted by the inverter 11 and then input to the AND gate 10, the AND gate 10 does not issue the disconnection signal S7 regardless of the presence or absence of the output signal S6 of the timer 9. Then, a disconnection signal S3 is issued from the main body control section 1 and input to the OR gate 12, and the power disconnection circuit 6 is activated by the output from the OR gate.

On the other hand, regarding the case where there is an abnormality in the main body control section 1, the main body control section 1 cannot issue the line acquisition confirmation signal S5 even though it has received the line acquisition signal S2 from the line control section 2. Therefore, the input of the AND gate 10 on the inverter 11 side is always positive. When a predetermined period of time has elapsed due to the operation of the timer 9, the output signal S6 is inputted from the timer 9 to the AND gate 10, and the AND gate 1
By 0, the positive input and S6 are ANDed and a disconnection signal S7 is output. This cutoff signal S7 is passed through the OR gate 12 to the power cutoff circuit 6.
is output to the terminal device and the power is turned off. Therefore, even if there is an abnormality in the main body control section and the main body control section 1 does not issue the disconnection signal S3, the power supply section can cut off the power to the terminal device in response to a command from the line control section 2. FIG. 4 shows the timing state of the line disconnection operation when the main body control unit 1 is abnormal. In this figure, since the timer 9 starts operating at the same time as the line acquisition signal S2 is output from the AND gate 5, the timer starts operating after a predetermined time has elapsed after the line acquisition request signal S1 or S4 is issued. This is done at the same time as the acquisition signal S2 is output. Then, when a predetermined time T has elapsed from the start of the timer, the timer 9 outputs an output signal S.
6 is issued, and along with this, AND gate 10
A disconnection signal S7 is output from. Note that when the main body control section 1 is working normally, after the line acquisition signal S2 is sent, the line acquisition confirmation signal S5 is output from the main body control section 1 after a predetermined time has elapsed, and when the power is turned off thereafter. The timer 9 is then reset.

In the above embodiment, in order to prevent the terminal device from being left without receiving the line use permission signal CS for a long time even though it has issued the line use right request signal RS on the line, or to In order to prevent the line from being left without permission to use the line due to an abnormality in the control unit, if a predetermined period of time has elapsed after the line acquisition request signal S1 or S4 was forcibly sent, the line control unit sends a signal equivalent to signal S2. Alternatively, the main body control section 1 generates a disconnection signal S3.

(6) Effects of the Invention As explained above, according to the present invention, the power can be cut off by a command from the line control unit even if the main unit control unit does not issue a disconnection signal after obtaining the line usage right. Therefore, an abnormality in the main body control section 1 will not interfere with turning off the power to the terminal device, and the operation for turning off the power to the terminal device can be performed more reliably.

[Brief explanation of drawings]

FIG. 1 is a diagram showing a conventional example of a control circuit for disconnecting a terminal device from a line, FIG. 2 is a timing diagram showing the operation of the control circuit in FIG. 1, and FIG. 3 is a diagram showing a power disconnection method of the present invention. FIG. 4 is a timing chart showing the operation of the first embodiment. DESCRIPTION OF SYMBOLS 1... Main body control part, 2... Line control part, 3... Power supply part, 4... RS synthesis circuit, 5, 10... AND gate,
6...Power cutoff circuit, 7...Power cutoff switch, 8,
12...OR gate, 9...timer, 11...inverter.

Claims (1)

[Scope of Claims] 1. When a plurality of terminal devices each having a main body control section and a line control section are connected to one line, and a certain terminal device leaves the line due to power cut, the terminal device loses the right to use the line. In a power cutoff method in which the power is cut off by a power cutoff signal from the main unit control unit after the terminal device acquires the right to use the line, the line acquisition signal generated when the terminal device acquires the right to use the line is input, and a predetermined line acquisition signal is input. A timer that generates an output signal after a period has elapsed, and a logical product of the output signal of this timer and a signal obtained by inverting the confirmation signal from the main unit control unit in response to the line acquisition signal input to the main unit control unit. A power cutoff for a terminal device, comprising an AND circuit that generates a cutoff signal, and the power is cut off based on a logical sum output of the cutoff signal and a power cutoff signal from the main body control section. method.