JP2000332914A - Modem - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily decide the difference between a connected terminal device or an arbitrary terminal device and a terminal device currently connected and to enable exactly the same operation of a terminal device with a certain terminal device by monitoring a signal line state, comparing information which is thus detected with previously stored information, and outputting their comparison result. SOLUTION: The modem 1 is connected between a terminal 2 and a public network 3 to enable a data communication between terminals 2 and 4 through an opposite modem 1' connected to the opposite side terminal 4. The modems 1 and 1' and terminals 2 and 4 are interconnected by ITU-T recommendation V.24 and V.28 and they are connected by modem cables 101 and 101'. The modems 1 and 1' are NCU buit-in modems which are widely used for data communication through the public network 3. A monitor part 12 of the modem 1 refers to monitor information in a storage part 13 and monitors plural interface signals between the terminal 2 and control part 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modem (modulator / demodulator), and more particularly to a modem connected between a data terminal device and a communication line.

[0002]

2. Description of the Related Art When a data terminal device performs data communication with a partner data terminal via a modem or a communication line, parameter setting considering compatibility with the operation of the partner terminal or the local modem is performed by the data terminal device. There is a need to do. Here, the parameter indicates a timer value or the like for monitoring a change in the control signal line.

When a terminal device connected to the modem is replaced, there is a case where only the connected terminal device is replaced without changing the setting of the modem, and there is a case where it is desired to realize the conventional communication as it is. In this case, even if the operation of the terminal device is intended to be the same as the operation of the conventional terminal device, the operation actually changes and it is not possible to connect with the other party, or an error in the communication protocol during the communication. May occur and communication may be interrupted.

[0004] Even in a new terminal device, since the communication parameters are made to be the same as those of the conventional terminal device in order to match the operation with the conventional terminal device, a setting error may occur. Also,
If the type of the terminal device changes, there is a case in which the parameters prepared in each terminal device disappear, or conversely, a new setting is required. Furthermore, even if parameters have the same name, there is a problem that stable communication cannot be performed due to a difference in operation because the method of realizing the “timer” function is different in each terminal device.

When such a failure occurs, it often occurs intermittently, and it is not easy to determine the cause of the failure.
In addition, since the accuracy of the monitoring time to be set on each terminal device is different, even if the same value is set, monitoring may actually be performed at a time different from the conventional one. That is,
It is necessary to detect a difference in operation from a conventional terminal device and realize the conventional compatibility of the terminal device.

Conventionally, for the purpose of eliminating the need to set and change the SG information of the terminal device on the terminal device side, for example, a "data terminal device" disclosed in Japanese Patent Application Laid-Open No. 8-107407 discloses a DCE (line There is disclosed a technique in which only the change on the end device side is required, and the change on the own device side is unnecessary. Similarly, Japanese Patent Application Laid-Open No. 6-268713 discloses a technique for calculating a communication protocol monitoring timer value from a transfer data length. This is a technique in which even if the data length / line speed of the data communication that has been realized is changed, the setting need not be changed each time.

As a technique on the modem or line terminal equipment side, Japanese Patent Application Laid-Open No. 62-56050 discloses a technique.
Monitors control signals from terminal devices from the viewpoint of noise suppression, transfers control information corresponding to the data transmission path only when the same state continues even after a signal change, and performs error control without changing the interface between terminal devices The technology which makes it possible is disclosed.

[0008]

The prior art described above is
It is not possible to know the difference in the operation of each terminal device that can be connected to the modem. These prior arts
Each of them can only cope with a certain kind of change / change, and it is impossible to realize the same operation because it is not intended to perform the same operation as in the past.

SUMMARY OF THE INVENTION It is an object of the present invention to easily recognize the difference between a conventionally connected terminal device or an arbitrary terminal device and a currently connected terminal device, and to perform operation of a terminal device which is exactly the same as a certain terminal device. The realization is to provide a modem.

[0010]

In order to solve the above-mentioned problems, a modem according to the present invention employs the following characteristic configuration.

(1) In a modem connected between the terminal device and the communication line for performing data communication between the terminal devices via the communication line, a monitoring unit for monitoring a signal line state; A modem comprising: a storage unit that compares detected information with information stored in advance; and an output unit that outputs the comparison result from the storage unit.

(2) The modem according to (1), wherein the output unit outputs the information to the outside when the two information do not match.

(3) The modem according to the above (1), wherein the monitoring unit includes a timer for monitoring and timing operation of the terminal device.

(4) The modem according to (3), wherein the monitoring unit has a buffer for temporarily storing monitoring data, on / off time values of the signal lines, and the like.

(5) The modem according to (1), wherein the storage unit stores information of a previous terminal device when the terminal device is replaced with another terminal device.

(6) The modem according to any one of (1) to (5), further including an input unit connected to the storage unit, and enabling information to be externally input to the storage unit.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a modem according to the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the configuration of a preferred embodiment of a modem according to the present invention. The modem 1 according to the present invention is connected between the terminal device 2 and the public network 3 and enables data communication between the terminal devices 2 and 4 via the partner modem 1 ′ connected to the partner terminal device 4. Modem 1,
ITU-T (International Tel.)
ecommunication Union-Telecommunication Sector)
Recommendation V. 24 and V.I. 28, and between them by modem cables 101 and 101 '.

The modems 1 and 1 'are connected to a public line (public network) 3.
NCU (Ne) widely used in data communication via
A modem with a built-in twork control unit function. The NCU function referred to here means that when a connected data terminal device needs data communication with a certain terminal device via a public line, the terminal device has a unique terminal device assigned to the other terminal device. This function is for sending a dial number to the public network 3 to call a partner to be connected, and for establishing a line connection with the partner terminal device.

Next, as shown in FIG. 1, the modem 1 includes a control unit 11, a monitoring unit 12 having a timer 12a and a buffer 12b, a storage unit 13, and an output unit 14. The control unit 11 modulates a transmission data signal from the terminal device 2 and demodulates a reception data signal from a communication line of the public network 3. In addition, handshake control of each control signal line for outgoing / incoming / receiving operations with the terminal device 2 is performed.

The monitoring unit 12 refers to the monitoring information in the storage unit 13 and monitors a plurality of interface signals between the terminal device 2 and the control unit 11. This DCE (Data
Circuit Terminating Equipment), ie, modem 1 and DTE (Data Terminal Equipment), ie, terminal device 2
The signal lines between them are defined in ITU-T Recommendation V24,
Each has a direction from DCE to DTE or from DTE to DCE. Here, the monitoring operation specifically monitors the data on the transmission data line (SD) and the reception data line (RD) and the on / off change of each control signal line, and monitors the data content and each measured signal. The line on / off time interval is compared with a corresponding value held in the storage unit 13. The timer 12a monitors the operation of the terminal device side by the monitoring unit 12 and counts time to measure the operation. On the other hand, the buffer 12b
Is a storage unit for temporarily storing data monitored by the monitoring unit 12 and on / off time values of the signal lines for comparison with values stored in the storage unit 13. The storage unit 13 stores the current terminal device connection state information (status), the corresponding event to be monitored (transmission / reception data and signal line change), and whether to start / stop the timer 12a when the above-described event occurs.
Operation information for performing value comparison or monitoring of a transition destination status or the like based on a comparison result and operation comparison information of a terminal device to be compared are stored.

The output unit 14 has a function of outputting the information to the outside when it is determined by the above comparison that the value is different from the held value.

Next, prior to the description of the operation of the modems 1 and 1 'shown in FIG. 1, the ITU-T Recommendation V.1 which controls and monitors the modems 1 and 1'. DCE-DT specified in 24
Each signal line between E will be described. A signal line that is a signal SD (Send Data) of JIS standard X5101 is a signal line from DTE to DC.
This is the transmission data line to E. RD of JISX5101
The (Receive Data) signal line is a reception data line from the DCE to the DTE. JISX5101 RS (Request
to Send) signal line is a control line controlled by DTE and DC
Indicates that there is data to be output to E. JISX510
One CS (Clearto Send) signal line is a control line indicating that the DCE can transmit data to the communication line. A DR (Data Set Ready) signal line of JISX5101 is a control line indicating that the DCE can operate. J
The ER (EquipmentReady) signal line of ISX5101 is D
TE is a control line indicating that data can be input / output to / from DCE. In the following description, JISX5101
Will be used.

The modems 1 and 1 'shown in FIG. 1 are used in connection with the public network 3, and are a global standard for calling and answering procedures between terminal devices connected when making and receiving calls. Operations shall be performed in accordance with the ITU-T Recommendation V25bis interface specifications. FIG. 7 shows a basic connection sequence between the terminal device and the modem at the time of the calling operation from the connection terminal device.

When the terminal device 2 needs to communicate with the partner terminal device 4 via the public network 3, the terminal device 2 first changes the signal ER from off to on. The modem 1 detects this and changes the signal CS from off to on.
Upon detecting this, the terminal device 2 sends a character string in which the telephone number of the communication partner terminal device 4 is added to the dial command for requesting the modem 1 to make a call on the signal SD. The modem 1 calls the communication partner terminal device 4 by sending the telephone number to the public network 3. Modem 1
Turns on the signal DR from off to notify the terminal device 2 when the other terminal device receives the call and recognizes the connection completion, and the terminal device 2 and the communication partner terminal device 4 shift to the data transfer phase. .

Next, the operation of the modem 1 shown in FIG. 1 will be described with reference to FIGS. FIG. 2 is a flowchart for explaining the operation of the modem, and FIG. 3 is a timing chart showing changes in each signal line. The operation sequence at the time of calling (dialing) from the local terminal device 2 in accordance with the ITU-T recommendation V25Bis interface specification is as follows. still,
At this time, the monitoring information tabulated in the state transition table in the storage unit 13 of the modem 1 is shown in FIG.

In the unconnected state before the terminal device 2 starts the transmission operation, the signal ER from the terminal device 2 (see FIG. 3A) is off, and the status of the storage unit 13 (see FIG.
(F) is the connection initial status A (step S1 in FIG. 2). Next, the monitoring unit 12 obtains the signal ER from the monitoring information (FIG. 5) corresponding to the count status in the storage unit 13.
Changes from on to off (see P1 in FIG. 3A) (step S2 in FIG. 2). When detecting the change of the signal ER from off to on (step S3 in FIG. 2), the monitoring unit 12 refers to the information in the storage unit 13 and refers to the timer 12a.
Is started to start timing (step S5 in FIG. 2),
Transition to the next status B (step S1 in FIG. 2)
0).

Based on this status, the monitoring unit 12 monitors whether the signal CS (see FIG. 3B) from the control unit 11 changes from OFF to ON (P2 in FIG. 3B) (FIG. 3B). Step S2). When the signal CS is turned on (step S3 in FIG. 2), the status changes to the next status C (step S10 in FIG. 2), and the signal RS from the terminal device 2 is turned on (see P3 in FIG. 3C). And the signal SD (FIG. 3)
Command data (see (d) of FIG. 3).
4) is expected (step S2 in FIG. 2).

This series of command data includes a CRN requesting the terminal device 2 or the modem 1 to make a dial call.
(Call Request with Number provided) The command character string is followed by dial number information (xxxxxxxxx) to the connection requesting partner terminal device 4 (P in FIG. 3D).
4) When receiving the dial number information following the character string (CRN), the control unit 11 sends the dial number to the public network 3 and performs a calling process to the connection partner terminal device 4.

When the monitoring unit 12 recognizes the command data on the signal SD (see FIG. 3D) from the terminal device 2 (step S3 in FIG. 2), it stores the command data received this time in the buffer 12b. I do. The monitoring unit 12 sequentially compares the value stored in the buffer 12b with the conventional data value stored in the storage unit 13 (step S7 in FIG. 2). If there is the same status, the status transitions to the next status D (steps S8 to S10 in FIG. 2), and the next monitoring is performed (step S2 in FIG. 2). However, if there is not the same one as a result of the comparison (step S8 in FIG. 2), a message indicating that the operation is different from that of the conventional terminal device is output to the output unit 14 (step S9 in FIG. 2). The value compared here corresponds to a command code including the other party's dial number when the terminal device 2 is connected to the line.

In the status D shown in FIG. 3 (f), the monitoring unit 12 changes the signal DR (see FIG. 3 (e)) from the control unit 11 from off to on (P5 in FIG. 3 (e)). Is detected, the completion of connection at the physical interface level is recognized, and the timer 12a stops counting time.

The above description is the operation from the time when the transmission processing from the terminal device 2 to the partner terminal device 4 succeeds until the line connection at the physical interface level is completed. Here, when the monitoring unit 12 is in one of the statuses B, C, and D (before DR is detected from OFF to ON), the signal ER (see FIG. 3A) from the terminal device 2 is changed from ON to OFF. Is detected, the signal ER is turned on from off from the time measured by stopping the timer 12a, that is, from the time when the terminal device 2 turns on the signal ER from off to on (P1 in FIG. 3A). The values up to are compared with the corresponding values stored in the storage unit 13, and if different, the fact is output to the output unit 14. The value compared here corresponds to the line connection monitoring time at the physical interface level in the terminal device 2, that is, the time for monitoring the signal DR on from the point in time when the signal ER is on.

The change of the signal ER from on to off is as follows.
Although the terminal device 2 monitors the change of the signal DR from the control unit 11 from off to on for a set period of time, the expected signal does not change. This means that it has been determined that the line connection with the partner terminal device 4 has failed, and the signal ER has been set to the initial state (off). By outputting from the output unit 14 that the time for monitoring the change of the signal DR from OFF to ON at the terminal device 2 is shorter than that of the related art, the user can set the terminal device 2 to the setting monitoring timer value. Changes can be made.

The above description is based on OSI (Open Systems Interco
nnection) This is an example of the monitoring operation of the line connection operation at the physical layer level in the basic reference model. After the completion of the connection operation, the process shifts to the data transfer phase. The data communication between the terminal device 2 and the partner terminal device 4 is a BSC (Bi) which is a typical procedure of the basic procedure.
nary Synchronous Communications) procedure.

Next, the BS after the physical level connection operation with the partner terminal device 4 is completed by the call from the terminal device 2
The operation sequence at the time of data link connection in the C procedure will be described with reference to FIG.

First, before the terminal device 2 on the transmission calling side starts data transmission with the partner terminal device 4, the partner terminal device 4
Sends a data sequence generally called an ENQ sequence in order to make a reception request to the side. FIG. 5 shows an example of a series of ENQ sequence data on the signal SD. In FIG. 5, PAD and PA are transmitted from the right terminal device 2 to the left modem 1 side.
D, SYN, SYN ... ID0, IDn, ENQ, PAD
In the order of character data. This E
Before and after the NQ sequence, there is continuous data of bit 1 usually called a mark state.

This sequence data is a sequence of characters in which each character is composed of 8 bits.
YN is a synchronization character for synchronizing characters so that the receiving terminal recognizes the bit string in character units.
The PAD is a character called padding for synchronizing bits. In addition, ID0 to IDn are communication partner identification numbers for confirming communication partners, and these character codes and the number of characters are characters and numbers that are defined in advance between terminal devices performing communication.

Upon receiving the ENQ sequence, the partner terminal device confirms that the connection request is destined for itself by this partner identification number, and returns an acknowledgment if communication is possible. Upon receiving this acknowledgment, the terminal device on the connection request side starts transmitting the information message to be returned for the first time.

Next, the monitoring operation of the modem 1 when the data link is connected will be described. FIG. 9 shows an example of the state transition table of the monitoring operation held in the storage unit 13 and comparison information when comparison is necessary.

In this phase, since the connection at the physical level has already been completed as described above, monitoring of each control signal is not necessary, and only transmission / reception data with the partner terminal device 4 on the signal SD / RD is monitored. Similarly to the operation in the line connection phase described above, the modem 1 holds data to be monitored according to the current status (step S1 in FIG. 2) in the storage unit 13 (status S2 in FIG. 2), Monitoring unit 1
2 is a buffer 12b that constantly stores data on the signals SD and RD.
The monitoring is performed by comparing the data to be monitored with the above while capturing the data (step S3 in FIG. 2).

First, an example of monitoring when the calling terminal device 2 transmits an ENQ sequence will be described. In this status, the modem 1 receives the signal SD transmitted from the terminal device 2.
As the above data, it is monitored whether or not one SYN character is transmitted. When the SYN character is recognized, a series of data strings including the SYN character is taken into the buffer 12b, and at the same time, each character included in the data is read. Each is compared, and the number of SYN characters is counted. Following the SYN, PAD, partner identification number, when the last character on the ENQ sequence, the ENQ character, is recognized, the number of SYN characters for character synchronization added before it,
The character code of the PAD character for establishing character synchronization, the number of PADs, and the partner identification number are compared with the conventional values stored in the storage unit 13 (step S7 in FIG. 2). If there is a different value, it is output to the output unit 14 (Step S9 in FIG. 2).

Here, the number of SYN characters, PAD
If the character code of the character and the number of PADs all match, and if there is a number that also matches the partner identification number, the timer 12
a is started (step S10 in FIG. 2), the status is shifted to the next status, and the occurrence of the next event is monitored (step S3 in FIG. 2). Here, if the partner terminal device 4 can communicate with the ENQ sequence from the terminal device 2, FIG.
Receive an acknowledgment on signal RD. If the partner terminal device 4 is in a communication disabled state or if the transmission timing and transmission data of the terminal device 2 are different from those in the related art, the partner terminal device 4 cannot recognize the reception of the ENQ sequence addressed to itself and returns a negative response, Or a response. At this time,
After the response monitoring time has elapsed, the terminal device 2 retransmits the above-described ENQ sequence as shown in FIG.

After recognizing the ENQ character from the terminal device 2 and receiving an acknowledgment from the partner terminal device 4 (step S4 in FIG. 2), the monitoring unit 12 stops the timer 12a (step S5 in FIG. 2). ). Upon receiving this acknowledgment, the terminal device 2 transmits information message data to the partner terminal device 4. Here, when there is no acknowledgment response from the partner terminal device 4 and the retransmission of the ENQ sequence from the terminal device 2 is recognized (step S4 in FIG. 2), the timer 12a is stopped (step S5 in FIG. 2). The measured time there is compared with a conventional value in the storage unit 13 (step S7 in FIG. 2), and if different, it is output (FIG. 2).
Step S9).

The value compared here is the ENQ of the terminal device 2.
This corresponds to the response monitoring time. The monitoring unit 12 continuously monitors the number of retransmissions from the terminal device 2, compares the number of retransmissions this time when the retransmission processing is completed, and outputs the value if different from the conventional value.

As described above with reference to the example, in the modem 1, the data transmission timing of the terminal device,
It is possible to output the difference from stored information such as transmission data, transmission interval and number of times, monitoring time for operation of the partner terminal device or modem, and the like to the outside.

[0046]

Next, another embodiment of the modem according to the present invention will be described with reference to FIG. Since the block diagram of the modem 1a in FIG. 6 includes the same components as the modem 1 in FIG. 1, the same reference numerals are used for convenience, and the description will focus on the differences. This modem 1a differs from the modem 1 of FIG.

The input unit 15 is connected to the storage unit 13 so that information settings such as comparison values in the storage unit 13 can be manually input from outside. In the modem 1a, the operation of the terminal device 2 can be monitored by an arbitrary setting independent of the operation of the conventional terminal device.
Further, as another embodiment, when monitoring the terminal device 2, the measured value is compared with the comparison value held in the storage unit 13 as needed, and if different, the fact is output. At the same time, it is updated as the current measurement value. This allows
The comparison value can be updated at any time. Also, a mode switch for monitoring / not comparing / not monitoring, that is, a mode input /
In some embodiments having a storage means, a value to be compared can be stored until after connection with another terminal device, and operability is improved.

The configuration and operation of the embodiment of the modem according to the present invention have been described above in detail. However, the present invention should not be limited to only such specific embodiments, and those skilled in the art can easily understand that various modifications can be made without departing from the gist of the present invention.

[0049]

According to the modem of the present invention, the difference between the currently connected terminal device and any terminal device to be compared can be recognized. The reason is that the operation of the terminal device can be monitored, and if there is a difference from the input comparison information, that information can be output.

Further, according to the modem of the present invention, it is possible to easily cope with a communication failure newly occurring due to the replacement of the terminal device, so that a smooth transition can be performed even when the connection terminal device is changed, and thus stable. Communication can be realized. The reason is that operation information of a conventionally connected terminal device is stored, operation of the currently connected terminal device is compared, and the operation information can be output.

[Brief description of the drawings]

FIG. 1 is a block diagram of a preferred embodiment of a modem according to the present invention.

FIG. 2 is a flowchart for explaining the operation of the modem in FIG. 1;

FIG. 3 is a timing chart of each signal in the modem of FIG. 1;

FIG. 4 is a diagram showing monitoring information tabulated in a state transition table in a storage unit 13 of the modem 1 in FIG. 1;

FIG. 5 is an example of data for performing a monitoring operation in the modem of FIG. 1;

FIG. 6 is a block diagram of another embodiment of a modem according to the present invention.

FIG. 7 is a sequence diagram showing signals when a modem originates a call according to the present invention.

FIG. 8 is a sequence diagram at the time of data link connection of the modem according to the present invention.

9 is a state transition table of a monitoring operation held in a storage unit 13 in FIG. 7 and one of comparison information when comparison is necessary;
It is a figure showing an example.

FIG. 10 is a sequence diagram at the time of data link connection of the modem according to the present invention.

[Explanation of symbols]

 1, 1 ', 1a Modem 2, 4 Terminal device 3 Communication line (public network) 11 Control unit 12 Monitoring unit 12a Timer 12b Buffer 13 Storage unit 14 Output unit 15 Input unit

Claims (6)

[Claims] A modem connected between the terminal device and the communication line for performing data communication between the terminal devices via the communication line; and a monitoring unit for monitoring a signal line state. A modem, comprising: a storage unit for comparing the obtained information with information stored in advance; and an output unit for outputting the comparison result by the storage unit. 2. The modem according to claim 1, wherein the output unit outputs the information to the outside when the two information do not match. 3. The modem according to claim 1, wherein the monitoring unit includes a timer for monitoring and timing operation of the terminal device. 4. The modem according to claim 3, wherein said monitoring unit has a buffer for temporarily storing monitoring data and an on / off time value of said signal line. 5. The modem according to claim 1, wherein the storage unit stores information on a previous terminal device when the terminal device is replaced with another terminal device. 6. The modem according to claim 1, further comprising an input unit connected to the storage unit, wherein information can be externally input to the storage unit.