JPH03154557A - Modem backup system - Google Patents

Abstract

PURPOSE:To surely satisfy the connection request by discriminating it as the occurrence of a fault to a MODEM when a call signal is detected over a prescribed time or over and replacing the MODEM with a standby MODEM. CONSTITUTION:A MODEM 111 receives a call automatically in response to the signal fed via a line 101 to apply modulation and demodulation of the signal and a standby MODEM 112 is connected to the line 101 and used when a fault takes place in the MODEM 111. A processing means 102 applies processing based on a data received and sent via the line 101 and a switching means 121 connects normally the MODEM 111 to the processing means 102 and the standby MODEM 112 is selected in response to the switching signal. A detection means 122 detects a call signal supplied via the line 101 and a discrimination means 123 judges that a fault takes place in the MODEM 111 when the call signal is detected over a prescribed time and generates a switching signal to supply it to the switching means 121. Thus, the communication disable due to a fault of the MODEM is prevented and the connection request of the line is surely satisfied.

Description

[Detailed Description of the Invention] [Summary] Regarding a modem backup method that automatically receives a call in response to a call signal, the purpose of this invention is to ensure that line connection requests are met. A modem that automatically receives a call and modulates and demodulates the signal in response to a calling signal, a standby modem that is connected to the line and used in the event of a failure of the modem, and data exchanged over the line. a processing means for performing processing based on the processing means; a switching means for normally connecting a modem to the processing means and switching to a standby modem in response to a switching signal; and a detection means for detecting a calling signal supplied via the line. and determining means for determining that a failure has occurred in the modem when the detecting means detects the calling signal for a predetermined period of time or longer, and generating a switching signal and supplying it to the switching means.

[Industrial application field]

The present invention relates to a modem backup method for a communication system using a switched line network, and more particularly to a modem buffering method for automatically receiving a call in response to a call signal supplied via the line. It is.

[Prior Art] For example, in so-called personal computer communication, in which a user's personal computer is connected via a switched line network and data is exchanged, a call signal from the user's modem is transmitted. The modem on the center side automatically receives the call.

Usually, a plurality of lines are connected to such a center side, and one modem is provided corresponding to each line. If a failure occurs in the network control unit (NCU) installed in the modem corresponding to each of these lines, and calls are not automatically received in response to the call signal supplied via the line, call the center. Unable to satisfy connection requests of existing users.

These modems at the center are inspected regularly, and modems in which a fault is detected are replaced with a normal modem, but modem faults that are not detected during these periodic inspections are Calls from users never arrive
It is first detected when restoration work is carried out in response to a notification.

[Problem to be solved by the invention]

By the way, with the above-mentioned conventional method, if a modem failure is overlooked during maintenance and inspection, detection work is started only when it can no longer actually meet the user's connection request, and the modem is replaced with a normal modem. be done. For this reason, there is a problem in that it takes time and manpower to restore the communication system, and a fail-safe mechanism has been desired.

In addition, if the line connection request is not satisfied due to a failure in the modem on the center side, the usage efficiency of the host computer on the center side and the usage efficiency of the user's computer will decrease, hindering the effective use of resources. It was getting worse.

The present invention was created in view of the above points, and an object of the present invention is to provide a modem backup method that reliably satisfies connection requests.

[Means to solve the problem]

FIG. 1 is a principle block diagram of a modem backup method according to the present invention.

In the figure, a modem 111 automatically receives a call in response to a call signal supplied via a line 101, and modulates and demodulates the signal.

The backup modem 112 is connected to the line 101 and is used when a failure occurs in the modem 111.

Processing means 102 performs processing based on data sent and received via line 101.

The switching means 121 normally switches the modem 111 to the processing means 1.
02, and according to the switching signal, the standby modem 112
Switch to .

Detection means 122 detects a calling signal supplied via line 101.

The determining means 123 determines whether the modem 1
11, generates a switching signal and supplies it to switching means 121.

[Function] Normally, the modem 111 and the processing means 102 are connected by the switching means 121, and in response to a call signal supplied via the line 101, the modem 111 automatically receives a call and starts communication. is about to start.

Here, if the modem 111 is normal, the incoming call operation is performed within a predetermined time after the supply of the above-mentioned calling signal is started.

On the other hand, if the modem 111 does not receive an incoming call within this predetermined time, it is considered that a failure has occurred in the modem 111, and in this case, even after the above-mentioned predetermined time has passed, the calling signal is not supplied. continues to be.

Therefore, the determining means 123 determines that the modem 11 is detected by the detecting means 122 for a predetermined period or more.
It may be determined that a failure has occurred in 1.

At this time, the determining means 123 generates a switching signal and supplies it to the above-mentioned switching means 121, and the switching means 121 switches to the standby modem 112 in response to this switching signal. As a result, using this backup modem 112, the line 101
Communication via is performed normally.

In the present invention, when the detection means 122 detects the calling signal for a predetermined period of time or more, the modem 11
By determining that a failure has occurred in modem 11,
It becomes possible to quickly detect a failure in the modem 112 and switch to the backup modem 112. This prevents communication from becoming impossible due to a failure in the modem 111, and
1 connection request can be reliably satisfied.

[Example] Hereinafter, an example of the present invention will be described in detail based on the drawings.

FIG. 2 shows the configuration of a communication system to which a modem back amplifier method is applied in an embodiment of the present invention.

(1) Here, the correspondence between the embodiment of the present invention and FIG. 1 will be shown.

Line 101 corresponds to line 205.

The processing means 102 corresponds to the host computer 203.

Modem Ill corresponds to modem 201.

Backup modem 112 corresponds to modem 202.

The switching means 121 corresponds to the switching circuit 243.

The detection means 122 corresponds to the calling signal detection section 244.

The determining means 123 corresponds to the central processing unit (CPU) 245.

Examples of the present invention will be described below assuming that the correspondence relationship as described above exists.

In Figure 2, 201 is a modem, 202 is a backup modem, 203 is a host computer, 205 is a line, and 240 is a monitoring device.

Line 205 is connected to modems 201 and 202, respectively, and modems 201 and 202 modulate and demodulate signals transmitted and received via line 205.

These modems 201, 202 and host computer 2
For example, as an interface with R3-2
32-C is applied.

The monitoring device 240 also includes the two modems 20 described above.
1, 202, two transmitting/receiving circuits 2
41a and 241b are provided, and R3-232-C
The corresponding modem 201, 2 via a cable adapted to
Connected to 02. In addition, the host computer 20
3, a transmitting/receiving circuit 242 is provided and similarly connected to the host computer 203.

Each of these transmitting/receiving circuits 241a, 241b is connected to a switching circuit 243, and normally the transmitting/receiving circuit 241a and the transmitting/receiving circuit 242 are connected to each other by this switching circuit 243.
is connected to the transmitting/receiving circuit 241b according to the switching signal.
and the transmitting/receiving circuit 242 are connected.

Further, the line 205 is connected to the calling signal detection unit 2 of the monitoring device 240.
44.

This calling signal detection section 244 is configured with a photocoupler 247 that operates in response to an alternating current signal supplied via the line 205. This photocoupler 247 is configured to output the potential at the collector of an internal phototransistor as a detection signal. Further, the emitter of this phototransistor is grounded, and the collector is connected to an input terminal 2° corresponding to one of the human power ports of the central processing unit (CPU) 245 of the monitoring device 240.

Further, the CPU 245 is provided with input ports corresponding to each of the signal lines between the switching circuit 243 and the transmitting/receiving circuit 242, and each of these signal lines is connected to the corresponding input port.

The CPU 245 operates based on a program stored in the memory 246 in advance, and detects the host as described below based on the signals supplied to each of the above-mentioned input ports and the detection signal from the call signal detection unit 244. It is configured to determine whether or not a failure has occurred in the modem 201 connected to the computer 203.

Hereinafter, the failure detection operation by the above-mentioned monitoring device 240 will be explained.

When a calling signal is supplied via the line 205, the photocoupler 247 of the calling signal detection unit 244 responds to this calling signal.
works.

Here, while the alternating current signal representing the calling signal is being supplied, the phototransistor of the photocoupler 247 is in an on state, so the potential at the collector of the phototransistor becomes logic 0''.

In this way, a detection signal that changes depending on the intermittent alternating current signal indicating the calling signal is supplied to the input terminal I2° of the CPU 245.

If the modem 201 is normal, a few seconds after the supply of the calling signal is started, the network control unit (not shown) provided in the modem 201 connects the line 205 and stops the calling signal.

Therefore, the detection signal indicating that the calling signal is supplied from the calling signal detecting section 244 is transmitted for a predetermined period of time (for example, 20
If the modem 201 is supplied for more than 2 seconds, it is considered that the modem 201 is not operating normally.

For example, the CPU 245 determines that a failure has occurred in the modem 201 when a logic "0" is further supplied as a detection signal 10 to 20 seconds after the logic "0" is supplied as the detection signal described above. 0゜According to this switching signal, the switching circuit 2
43, the transmitting/receiving circuit 241b corresponding to the backup modem 202 is connected to the transmitting/receiving circuit 242 on the host computer side, and communication via the line 205 is normally performed using the modem 202.

As a result, even if a fault occurs in the modem 201 that prevents the automatic call receiving operation, this fault is quickly detected as described above, and the modem 202 is switched to the backup modem 202.

Therefore, the modem 201 will not be left unattended until communication becomes impossible due to this fault, and it is possible to prevent communication from becoming impossible due to a fault in the modem 201. Line connection requests from users who wish to use the host computer 203 can be reliably satisfied.

Also, during communication, as described above, the CPU 24
5 monitors the signals sent and received between the host computer 203 and the modem 201 by monitoring the signals supplied to each input port.

For example, if the data set ready (DR) from the modem 201 does not become a logic "°1°" within a predetermined time after the terminal device ready (ER) from the host computer 203 becomes a logic "1", , the CPU 245 may determine that a failure has occurred in the modem 201.

In this case, after the communication via the line 205 is once completed, a switching signal is output and supplied to the switching circuit 243 to switch to the backup modem 202. This results in
Thereafter, communication via line 205 is normally performed using modem 202.

In addition, the CPU 245 receives not only the signals of the input ports corresponding to the ER and DR described above, but also the signals of the host computer 20.
3 and the input port signals corresponding to the received data from the modem 201, and if these do not change by a predetermined amount of time (for example, 1 minute) or more, it is determined that a failure has occurred in the modem 201. You may also do so.

Furthermore, a program for analyzing the contents of the transmitted data and received data may be stored in the memory 246, and it may be determined whether or not a failure has occurred in the modem 201 based on the results of this analysis.

In this way, host computer 203 and modem 2
By monitoring the transmission and reception of signals to and from the modem 201, even after a call arrives at the modem 201 and communication has started, modem failures are detected in parallel with communication, and the modem in which a failure is detected is backed up. It becomes possible to switch to a modem for

As a result, from now on, calls can be received by the normal modem 202 and communication can be performed normally.

Further, when a failure of the modem 201 is detected when receiving a call or during communication as described above, the monitoring device 240
By notifying the host computer 203 that an abnormality has occurred in the modem 201 and switching to the modem 202, maintenance personnel can be prompted to replace the modem 201. 240 may be provided with a display section, and the above-mentioned notification may be displayed on this display section to prompt the user to replace the modem 201.

[Effects of the Invention] As described above, according to the present invention, a failure in the modem is quickly detected and switched to a backup modem based on the detection result of the calling signal by the detection means, thereby preventing communication due to a failure in the modem. This is extremely useful in practical terms, as it prevents the line connection from becoming impossible and ensures that line connection requests from users are met.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of the principle of the modem backup method of the present invention, and FIG. 2 is a block diagram of a communication system to which the modem backup method according to an embodiment of the present invention is applied. 246 is a memory, and 247 is a photocoupler. In the figure, 101 is a line, 102 is a processing means, 111 is a modem, 112 is a backup modem, 121 is a switching means, 122 is a detection means, 123 is a determination means, 201.202 is a modem, 203 is a host computer, 205 is a line, 240 is a monitoring device, 241 and 242 are transmitting and receiving circuits, 243 is a switching circuit, 244 is a calling signal detection unit, 245 is a central processing unit (CPU),

Claims (1)

[Claims] (1) A modem (111) that automatically receives a call in response to a calling signal supplied via a line (101) and modulates and demodulates the signal; )
Backup modem (112) used when a failure occurs
and a processing means (102) that performs processing based on data exchanged via the line (101), and usually, the modem (111) is connected to the processing means (102), and the modem (111) is connected to the processing means (102) and switching means (121) for switching to the standby modem (112); detecting means (122) for detecting a calling signal supplied via the line (101); is detected for a predetermined period of time or more, the modem (111
) determination means (123) that determines that a failure has occurred in the switch, generates the switching signal and supplies it to the switching means (121);
A modem backup method characterized by comprising: and.