JP4274297B2 - Remote control method and apparatus using telephone line - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a remote control method and apparatus using a telephone line, and more particularly, means for avoiding that a remote installation apparatus remotely controlled through a telephone line such as a general subscriber telephone can not be controlled. The present invention relates to a remote control method and apparatus using a telephone line.
[0002]
[Prior art]
For example, a relay antenna that transfers radio waves from a vehicle equipped with a TV repeater to a broadcasting station is usually installed on a high tower because it needs to follow a freely moving vehicle. The feed is remote controlled. Such a device is generally made to operate by software input to a built-in computer.
[0003]
[Problems to be solved by the invention]
By the way, among the performances required for a device installed away from the place where the control signal is transmitted and operated by software (hereinafter referred to as “far-site installation device”), the problem is the stable operation performance. It has been empirically known that a device that operates by software is very often able to recover from a failure in an emergency avoidance when a so-called reset operation is performed by turning the power off and then on again.
[0004]
The cause of the failure when the abnormal operation appears most frequently is a memory leak caused by continuous operation all day, that is, a failure caused by a bug in the application and the operation system. In spite of securing the RAM area one after another during the operation. In other words, this is a failure caused by a state where the reserved RAM area is not released.
[0005]
When a remote installation device equipped with a buggy application and operation system is operated all day, it seems that it is operating normally because there is a RAM area to acquire for the first time, but eventually there is no RAM area to acquire. At that time, the application and the operation system become inoperable (hang up), and an abnormal operation occurs. If the RAM area is exhausted, all RAM areas are released when reset, so in the above case where normal operation can be performed for a certain period after reset, if the cause of the memory leak failure can be determined, Although abnormal operation can be prevented, it is usually a very long time to investigate the cause, and in reality it is necessary to respond by resetting as an emergency measure until the cause is determined. .
[0006]
Yet another problem is that unattended continuous operation is normal for remote installation equipment, so if any failure occurs, it is often difficult for a person to rush to reset the remote installation equipment. Even if it is installed on a high tower, there is a problem that reset operation is extremely difficult.
[0007]
As a conventional technique for such a self-healing method for abnormal operation of remotely installed devices, a method of resetting a CPU (central control unit) by a watch timer (hereinafter referred to as “WDT”) is widely known. This WDT method is a process in which the CPU processes a program stored in a ROM, resets the WDT within a specified time, and resets the WDT again within a specified time after the WDT is reset. .
[0008]
The mechanism of this method is that if any hang-up occurs in the program processing process, the CPU cannot reset the WDT within a specified time, so the CPU monitoring circuit outputs a reset signal to the CPU. , So that you can get out of the hang-up state.
[0009]
However, in this method,
It is impossible to reset the CPU at a specific timing according to the intention of the controller.
B A dedicated WDT circuit is required.
C) If the WDT function operates normally, it means that the entire device is operating normally even if other functions are in an abnormal state, and it cannot necessarily be said that a self-recovery operation for a fault can be performed.
There is a problem.
[0010]
In the remote control described above, the purpose of the remote control is sufficiently fulfilled only when the telephone line is connected while the remote device is operating reliably. Therefore, the CPU status is monitored during other periods, that is, when the line is disconnected. Is not so important.
[0011]
The present invention has been made paying attention to the features described above, and provides a remote control method and apparatus using a telephone line that can reliably reset the CPU each time at a specific timing when the telephone line is connected. The purpose is that.
[0012]
[Means for Solving the Problems]
In order to achieve the above object, a remote control method using a telephone line according to the present invention provides a modem for a remote installation device that is remotely controlled by a control signal sent from the telephone line. It is set to recognize that it is in a communicable state, and when the modem receives a reception carrier, that is, when a line connection is confirmed by an incoming / outgoing call of the modem, software for controlling a remote installation device corresponding to the communication is installed. The communication control unit is restarted and initialized, so that the modem does not disconnect from the telephone line even during the initialization operation.
[0013]
The remote installation device used in the present invention naturally corresponds to the case where the distance from the terminal installed in the control room transmitting the control signal is long, but in addition to that, the remotely controlled device can be a general subscriber telephone line or other It means all devices that are remotely controlled through a telephone line. Further, the control device targeted by the present invention targets all devices that operate by controlling the on / off of the switch.
[0014]
The modem is a device for connecting a data terminal device to an analog telephone line, and a conventional one can be used as it is. Note that modems generally do not have the problem of requiring the reset operation.
[0015]
In order to achieve the above object, the remote control device using the telephone line of the present invention is a remote installation device remotely controlled by a control signal sent via the telephone line, the remote installation device comprising a modem, Composed of a communication control unit equipped with software for controlling a remote installation device corresponding to the control signal, and a reset signal generation unit, when the modem detects a received carrier, a carrier detection signal is output to the reset signal generation unit The reset signal generator that receives the signal initializes the communication control unit, and the modem indicates a signal indicating whether the communication is enabled or disabled even while the communication control unit is in a communication disabled state. The output unit to output and the input unit to which the communication control unit inputs a signal indicating a communicable state or incapable state are short-circuited, and the input unit is connected to the state of the communication control unit. Razz always it is configured such that a signal is input, the remote control device in which the modem is using the telephone line so as not to cut the connection with the telephone line.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.
[0018]
A remote installation device 1 using a telephone line according to the present embodiment includes a communication control unit 2, a modem 3, and a reset signal generation circuit 4 as shown in FIG. It is connected to a terminal 7 for issuing a control command installed in a control room (not shown) to which a line is connected. Reference numeral 8 in FIG. 1 denotes a modem that connects the transmission / reception device 7 and the telephone line 6, and the communication control unit 2 is a portion that transmits and receives data in the remote installation device 1.
[0019]
Data transmission / reception between the communication control unit 2 and the modem 3 is performed via the bus 9. A transmission request terminal RS provided in each of the communication control unit 2 and the modem 3 is a line control terminal that outputs a transmission request signal (RS signal) of received data from the communication control unit 2 to the modem 3. .
[0020]
The modem 3 is a modem having a general configuration that is attached to the remote installation device 1. The DR terminal provided in the modem 3 is a line control terminal for outputting a data set ready, that is, a signal (DR signal) for transmitting a communication possible state (ON) / impossible state (OFF). If the modem 3 is communicable with the telephone line 6, the DR signal is communicable (on). The ER terminal is a terminal for inputting whether the data terminal is ready, that is, whether the communication control unit 2 is in a communicable state (ON) or an incapable state (OFF). In the present embodiment, the DR terminal and the ER terminal are short-circuited, and the DR signal is continuously applied to the ER terminal so that the modem 3 is not affected at all by the communicable state or impossible state of the communication control unit 2. I made it.
[0021]
A CD terminal provided in the modem 3 is a terminal that outputs a signal (CD signal) indicating carrier detection, that is, a state in which the modem detects a reception carrier (ON) and does not detect (OFF), and a reception carrier detection signal ( When the reset signal generation circuit detects ON, a reset signal is output to the CPU. Here, the carrier means a carrier wave on the telephone line 6.
[0022]
When the remote installation device 1 is turned on, the software state transitions as shown in FIG. The remote installation device 1 in the power-on state executes processing 1 and processing 2 shown in FIG. 2 every time the power is turned on, and accordingly, the state of the communication control unit 2 is changed from state i to state c. It is configured to change.
[0023]
In process 1, communication parameters are set. The communication parameter setting is a general setting in this type of communication, that is, a fixed value for the communication speed and the format of the communication message, and one of them is an item for controlling on / off of the RS control signal, In process 1, the RS signal is set to OFF.
[0024]
Next, in process 2, the presence or absence of CD detection, that is, reception carrier detection is determined. Subsequent processing is branched depending on the on signal / off signal detection result of the CD signal output from the modem 3 (processing 2 in FIG. 2).
[0025]
In the process 2, when the modem 3 is called, that is, when it is not in the incoming call state, the modem 3 has not detected the reception carrier (telephone line is disconnected), and the communication control unit 2 for performing the communication operation is in the idle state (see FIG. 2), the RS signal is set to ON (the reason will be described later), and the modem 3 is initialized to perform serial communication between the modem 3 and the communication control unit 2.
[0026]
When the remote installation device 1 is called from the transmission / reception device 7 in the idle state (incoming call) or the remote installation device 1 calls the transmission / reception device 7 (outgoing call), the state transitions to state b. When the line connection completion signal “CONNECT” is received from the modem 3 in the state B, the state shifts to the state C. At this timing, the CD signal is raised from OFF to ON (B in FIG. 3), and the output of the reset signal generation circuit 4 The signal (ON signal) is converted into a reset pulse signal (negative pulse signal in FIG. 3), and the CPU on the communication control unit 2 is hardware reset. That is, the communication control unit 2 is reset, but the modem 3 is not reset, so that the modem remains in the line connection state, that is, the CD signal is kept on, and the communication control unit 2 is in exactly the same state as after the power is turned on. That is, returning to the initial state, it becomes possible to execute the process 1 again.
[0027]
In this case, if the ER signal that is an input signal to the modem 3 is turned off even for a moment, the modem 3 disconnects the line with the modem 8. Originally, the ER terminal of the modem 3 is generally connected to the ER terminal of the communication control unit 2, but the communication control unit 2 is reset at the timing of receiving the line connection completion signal “CONNECT” as described above. If the ER terminal of the modem 3 and the ER terminal of the communication control unit 2 are connected, the modem 3 disconnects the line with the modem 8.
[0028]
Therefore, the telephone line 6 is prevented from being disconnected by inputting the DR signal of the modem 3 that does not turn off even at the reception timing of the line connection completion signal “CONNECT” to the ER terminal of the modem 3 (E in FIG. 1). ing. That is, since the DR signal of the modem 3 is on when the communication control unit 2 is reset, the ER signal of the modem 3 is also turned on after all, and the line connection state when the communication control unit 2 is reset can be maintained.
[0029]
When the reset is performed, the RS signal is set to OFF in process 1 as described above. For example, data such as a communication message and a control message is transmitted from the transmission / reception device 7 during the reset operation (A in FIG. 3). However, since these data are not sent to the signal control unit 2 during the reset process and are stored in an internal buffer (not shown) of the modem 3, there is no loss of data received during the reset process. .
[0030]
Thereafter, since the CD signal is determined to be on by the CD detection in process 2 (C in FIG. 1), the state transits directly to state c (line establishment state) without going through states a and b (F in FIG. 2). Then, the communication control unit 2 can turn on the RS signal and start data transmission / reception with the modem 3.
[0031]
When the telephone line 6 is disconnected after the data transmission / reception between the modem 3 and the modem 8 is completed, the modem 3 transmits a carrier unconfirmed “NO CARRIER” to the communication control unit 2 and simultaneously turns off the CD signal (FIG. 3). To G). However, the reset signal output from the reset signal generation circuit 4 remains in the off state. Therefore, when the telephone line 6 is disconnected, the communication control unit 2 is not reset (H in FIG. 3), and the state transitions from the state C (FIG. 2, the same applies hereinafter) to the state A with “NO CARRIER” as a trigger. In state i, the software is in a standby state.
[0032]
【The invention's effect】
As described above, the remote control method and apparatus using a telephone line according to the present invention resets the communication control unit by hardware each time a call is made when a remote installation apparatus is remotely controlled through a general telephone line. The RAM area is fully released and returned to the initial state. In addition, the modem maintains the line connection state even during the period when the communication control unit is incapable of communication control due to the hardware reset operation, so even if the communication control unit reaches the hang-up state, the incoming call Thus, the communication control unit is restored and data transmission / reception becomes possible again. Therefore, even if the application and operating system are faulty due to a bug and the low-reliability communication device is operating unstablely, it can be operated unattended as a remote installation device, improving the reliability of the entire communication system. Can be made.
[Brief description of the drawings]
FIG. 1 is a block circuit diagram for explaining an overview of a remote control device using a telephone line according to an embodiment of the present invention;
FIG. 2 is a software state transition diagram of the control device of FIG. 1;
FIG. 3 is a time chart showing a waveform of a control signal reset signal of the control device of FIG. 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Remote installation apparatus 2 Communication control apparatus 3 Modem 4 Reset signal generator 6 General subscriber telephone line 7 Transmission / reception apparatus

Claims (1)

In a remote installation device remotely controlled by a control signal sent via a telephone line, the remote installation device includes a modem, a communication control unit equipped with software for controlling the remote installation device in response to the control signal, and It consists of a reset signal generator,
When the modem detects a received carrier, it outputs a carrier detection signal to the reset signal generation unit, the reset signal generation unit receiving the signal initializes the communication control unit, and the communication control unit is in a communication disabled state Even while
The modem outputs a signal indicating a communicable state / impossible state, and the communication control unit short-circuits an input unit that inputs a signal indicating a communicable state or an incapable state, and the communication unit A remote control device using a telephone line in which a signal is always input regardless of a state of a control unit so that the modem does not disconnect the telephone line.

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