KR950003663B1 - Remote check method of modem - Google Patents

Abstract

(1) attempting the originating MODEM of the maintenance center to connect to the incoming MODEM of the remote place; (2) transmitting a remote diagnosing request signal by the originating MODEM; (3) responding to the remote diagnosing request signal and performing the MODEM connecting operation of the remote diagnosing function; (4) receiving the remote diagnosing command word and transmitting it to the incoming MODEM; (5) analyzing the remote diagnosing command word and making the MODEM state data according to the corresponding command word; (6) displaying the received state data; and (7) transmitting the maintenance data to the originating MODEM according to the diagnosing result of the remote receiving data.

Description

Modem Remote Diagnosis

1 is a block diagram of a modem.

2 is a remote delivery connection procedure of a modem.

3 is a flow chart of remote diagnosis connection of a modem according to the present invention.

4 is a flowchart of remote diagnosis of a modem according to the present invention.

* Explanation of symbols for main parts of the drawings

10: central processing unit 20: ROM

30: RAM 40: DIP switch part

50: key panel 60: display unit

70: I / O control unit 80: DTE connection unit

90: communication unit 100: wall demodulation unit

110: rotation control unit

The present invention relates to a method of transmitting a state of a modem, and more particularly, to a method of unattended diagnosis of a state of a remotely spaced modem.

In general, a modem is a device that transmits data in a synchronous or asynchronous manner through a telephone line or a dedicated line, receives a command from a terminal, processes corresponding functions, and displays the result on the terminal side. Such a modem is composed of precision electronic components (VLSI) and the like to implement a data communication function between a terminal and a remotely spaced modem, and store optional parameters (S register values) for implementing various functions in a nonvolatile memory device. To implement various functions.

At this time, the user of the modem requests maintenance to an A / S center when an abnormal state occurs while using the modem. In this case, maintenance personnel visit the site where the modem is installed and perform the function of diagnosis and diagnosis of the modem.

However, the user of the modem is not an expert who can fully understand the configuration and various functions of the modem, and thus requires the maintenance function even in the abnormal state caused by the wrong input of the command or the wrong operation of the device. In other words, even if it is not an abnormal condition caused by a fatal defect of the modem but a simple functional error, the maintenance center personnel directly visits and performs a diagnostic function, thereby causing a loss of manpower and time.

Accordingly, an object of the present invention is to provide a method for remotely diagnosing the state of a modem to determine the presence of an abnormal state.

Another object of the present invention is to provide a method for remotely maintaining an abnormal state after analyzing the abnormal state of the modem by accessing the modem at the request of the modem user.

Hereinafter, the present invention will be described in detail with reference to the drawings.

1 is a configuration diagram of a modem according to the present invention, the central processing unit 10 controls the overall operation of the modem, and controls the data communication function (Data Terminal eguipment: hereinafter referred to as DTE) data communication path of the DTE Control the formation. The ROM 20 stores an operation program of the central processing unit 20 and stores initial service data (install data). The RAM 30 temporarily stores various data generated during program execution under the control of the central processing unit 20. The DIP switch unit 40 is located on the rear panel of the modem, and generates a signal for performing a corresponding function according to the position of each DIP switch. The key panel is located on the front panel of the modem, and generates a signal to perform a corresponding function according to the on / off state of each switch. The display unit 60 is located on the front panel of the modem and consists of LEDs. The display unit 60 displays various states of the modem to be received. The I / O control unit 70 is connected between the DIP switch unit 40 as an input device, the casing 50, the display unit 60 as an output device, and the central processing unit 10. The I / O control unit 70 outputs a signal generated from the DIP switch unit 40 and the key panel 50 to the central processing unit 10, and outputs a modem state signal output from the central processing unit 10. It outputs to the display part 60. The DTE connection 80 is connected to the DTE via an RS-232C cable. The DTE interface 80 interfaces data at the RS-232C level between the modem and the DTE. The communication unit 90 is connected between the DTE connection unit 80 and the modulation and demodulation unit 100 and controls the formation of a modem communication path under the control of the central processing unit 10. The modulation and demodulation unit 100 is connected between the communication unit 90 and the line control unit 110, and modulates the data RXD output from the communication unit 90 under the control of the central processing unit 10 to transmit an analog transmission signal TXA. The analog receive signal RXA is demodulated and converted to digital data TXD. The rotation control unit 10 is connected to a telephone line or a dedicated line and performs an interfacing function with a remote modem under the control of the central processing unit 10.

Here, the configuration of the DIP switch unit 40, the key panel 50 and the display unit 60 will be described. First, the DIP switch unit 40 is composed of 10 DIP switches of a modem, and performs a function as shown in Table 1 below.

TABLE 1

In addition, the switch configuration of the key panel 50 and the function of each switch are shown in Table 2 below.

TABLE 2

Finally, each LED configuration and display function of the display unit 60 is as shown in Table 3 below.

TABLE 3

The modem receives an asynchronous data type command from the DTE and sets and modifies various parameters. All modem types used herein always start with AT. Therefore, the command system used at this time is called an AT command. The AT command is a command system made by Hayes of the United States and is the most commonly used command. The form of the AT command as described above is as follows.

CR: Carriage Return

LF: Line Feed (LF can be omitted)

2 is a flowchart for performing remote diagnosis. When the calling modem performs a dialing function and calls an arbitrary modem, the called modem transmits an answer tone when receiving a ring signal.

At this time, when the calling modem receives the response tone, a training sequence signal for adjusting the communication speed is sent to the called modem. The called modem also adjusts the communication speed with the calling modem by delaying a predetermined time after sending the answer tone. Send a training sequence signal for. If the communication speed is specified between the calling modem and the called modem, the calling modem sends the remote diagnosis request data 'ENQ'.The called modem checks the status of DIP switch DIP ₁₀ . Send response data 'R', 'M'. At this time, when the calling modem receives and detects the remote diagnosis response data 'R' and 'M', the called modem is transferred to the remote diagnosis state under the control of the calling modem. Here, the calling modem may be a modem of a system maintenance center, and the called modem may be any modem remotely separated from the system maintenance center. FIG. 2 shows the procedure for making the remote diagnosis as described above.

3 is a flowchart illustrating operation occurring upon connection of a remote diagnosis according to the present invention.

4 is a flow chart of the operation of the remote diagnosis according to the present invention. After the connection of the remote diagnosis function as shown in FIG. The process of transmission is shown.

Based on the above-described configuration, the present invention will be described in detail with reference to FIGS.

In general, a modem performs full duplex communication at various transmission speeds (9600bps, 4800bps, 2400bps, 1200bps, 300bps) connected between a DTE and a telephone line or a dedicated line. In addition, the communication standard can support V.32, V.22bis, V.22, V.21, BELL 212A / 103, etc. In addition, in performing the communication as described above, it has a data compression function and an error correction capability, and as a mode for performing a communication function, it is possible to implement a manual or automatic incoming / outgoing mode. It can also determine the designated connection speed automatically for incoming and outgoing connections. Such various functions can be implemented by the DIP switch 40 or the key panel 950, and the desired function can be set as the AT command.

Here, look at the type and function of the AT command (Table 4).

TABLE 4

In the AT command list, n denotes a parameter, r denotes a register number, B denotes a bit mark, x denotes a number, [] denotes an initial setting value, and an @ denotes a value stored in a nonvolatile memory device.

In addition, the DIP switch 40 is made of 10 DIP switches to perform a variety of functions, each function is as follows.

First, DIP switch _1, DIP _1, is placed upward when you want to transfer data using CCITT V.42bis data compression. The CCITT V.42 bis is a function that a modem analyzes data inputted from a terminal, encodes repeated data, and manufactures and transmits data to reduce and transmit the actual amount of data transmitted between the modems. Even for a terminal having a high data transmission rate, data transmission and reception are made possible.

Secondly, DIP # ₂ DIP ₂ is used to activate the data error communication function in accordance with CCITT V.42. The CCITT V.42 checks whether there is an error between the data transmitted and received between the modems, and sends a data without error by requesting retransmission to the counterpart when an error occurs. CCITT V.42 enables perfect error detection by using a cyclic redundancy check (CRC) method for error retrieval.

Third, DIP switch No. 3 DIP ₃ is a switch that sets the data transmission type of the modem. If it is set up, it is synchronous (Synchronous), and if it is set down, it is set Asynchronous. In addition, even if the position is down, synchronous communication is possible following the commands (AT & Mn). At this time, since the modem does not receive a command from the terminal during synchronous communication, the dialing may use the [auto-call] switch of the panel 50. Asynchronous data is transmitted by attaching a start bit and a stop bit to each character data. The asynchronous data is applied to most communication using a database using a general telephone line.

Fourth, DIP switch # 4 DIP ₄ sets whether the modem should answer automatically when the incoming ring rings. If the switch is set up, the modem will automatically detect the ring when the incoming ring is ringing and automatically attempt to connect to the answer mode when the ring comes in as much as the value of the S0 register. If the register has a value greater than or equal to 1, the modem will operate in auto answer mode. To operate the modem in manual call mode, switch 4 must be down and the S0 register value must be zero.

Fifth Fifth Switch DIP ₅ displays help in Korean or English displayed on the screen when the [Help] switch is pressed. At this time, if you use a terminal that supports Hangul, it is convenient to use Hangul mode.

Sixth, DIP switch No. 6 DIP ₆ is a flow control function that is used when it is necessary to adjust the amount of data received because the buffer stored between the terminal and the modem becomes full in data transmission and reception. DIP switch is a switch to set whether flow control is performed by XON / XOFF character data. The function of this DIP switch is valid only when DIP switch 1 (CCITT V.42 function selection) or DIP switch 2 (CCITT V.42 bis) is ON. (XON: Data transmission request, XOFF: Data transmission stop request)

Seventh, DIP switch # 7 DIP ₇ is used to set the flow control function by RTS / CTS in the flow control method. The function of this dip switch is only valid when DIP switch 1 (CCITT V.42) or DIP switch 2 (CCITT V.42 bis) is placed up. RTS / CTS flow control is a method of performing flow control using an RS232C cable signal line connected between a terminal and a modem. RTS is a signal for requesting transmission from a terminal to a modem, and CST is a transmission permission signal for a modem. to be. To use this method, pins 4 and 5 of the RS232C cable must be used.

The eighth DIP switch DIP ₈ is used to check the speed of the terminal. There are two ways for the modem to recognize the terminal speed. One of them is by the terminal speed selector switch on the front panel, and the other is by the AT command. If the 8th DIP switch on the rear panel is put down, the modem will follow the setting of the terminal speed selector switch on the front panel. If the switch is placed up, the modem will automatically recognize the speed from the "AT" command.

Ninth DIP Switch No. 9 DIP ₉ is a switch that selects whether the modem is to be used on a switched or dedicated line.

Lastly, DIP switch No. 10 DIP ₁₀ is a switch that is used when an abnormal condition occurs while using the modem and the after-sales service of the system maintenance center is required or the password is forgotten. In other words, when this switch is pushed up, the remote maintenance communication can be implemented to transmit the system status information to the remote maintenance center to implement other remote diagnosis functions in the state of the corresponding modem.

As described above, the modem may implement various modem communication functions by using an AT command, and may also implement various functions by operating each switch of the DIP switch unit 40 and the key panel 50. However, the operator using the modem does not know and use all the functions of the modem, but knows and uses only some of the operating methods. Can be. In this case, the operator will request after-sales service from the system maintenance center.

At this time, in order to implement the power diagnostic function unattended in the modem to implement the remote DIP switch 10 for setting the remote diagnosis function on the DIP position (40).

Therefore, if an abnormal condition occurs in a remote modem, use the telephone to call the system maintenance center. Then, the personnel of the maintenance center and the remote diagnosis function are required, and the DIP switch DIP ₁₀ of the DIP switch unit 40 of the modem is raised upward. The personnel in the maintenance center then attempts to connect the modem to establish a communication path with the remote modem. At this time, an incoming ring signal is generated by the telephone of the system maintenance center. If the telephone is left without hooking off, the modem connection between the modem of the system maintenance center and the remote site is established.

It is assumed here that the modem of the system maintenance center is called the calling modem, and the remote modem is called the dialing modem. In order to perform the remote diagnosis function, when the called modem is called by the 'ATDM XXXX' command from the calling modem, the communication path for the remote diagnosis is formed between the calling and the receiving modems in the same manner as in FIG. 2 and FIG.

First, when the originating modem receives the 'ATDM XXXX' command through the DTE access unit 80 from the DTE, the call modem recognizes that the call mode is called in step 301 and dials the received information according to the command language. Output to telephone line or leased line through. Thereafter, in step 302, the originating modem checks whether a response tone is received from the called modem.

At this time, when the incoming modem receives the incoming ring signal from the telephone line or the dedicated line through the circuit control unit 110, it recognizes that the answer mode is in step 351, and responds for about 3 seconds as the second degree in step 352. The tone is transmitted to the telephone line or the dedicated line through the line control unit 110.

When the response tone is received from the terminating modem as described above, the originating modem recognizes this in step 302 and transmits a training sequence signal in step 3603. The training sequence signal is a signal for matching the modem connection speed and the communication protocol between the calling modem and the called modem. The calling modem transmits the training sequence signal when receiving a response tone from the called modem. Immediately after the transmission, the training sequence signal is transmitted. The output sequence of the training sequence signal is the same as that of the second diagram, and the transmission of the training sequence signal is stopped when the connection speeds between the modems match.

After the transmission of the training sequence signal is stopped, the originating modem recognizes the modem attempting the remote diagnosis connection to itself in step 304, and thus transmits the remote diagnosis request data ENQ as in the second method. At this time, the transmission modem repeatedly transmits ENQ of even parity and ENQ of odd parity when the remote diagnosis request data ENQ is output. As described above, the calling modem checks whether the response data 'R' and 'M' are received in response to the remote diagnosis request generated from the called modem in step 305 after outputting the remote diagnosis request data ENQ.

In addition, after stopping transmission of the training sequence signal, the terminating modem checks whether the remote diagnosis request data ENQ is detected in step 354. At this time, if the DIP switch No. 10 of the DIP switch unit 40 is lifted up, after detecting the reception of the remote diagnosis request data, in step 355, response data 'R' and 'M' for the remote diagnosis request are detected. Will print

As described above, when the calling modem detects the reception of 'R' and 'M' data repeatedly transmitted from the called modem in step 305, it transitions to the connected state with the called modem in step 306 and proceeds to the remote diagnosis function routine. do. In addition, the terminating modem transmits the 'R' and 'M' data, and then proceeds to step 306 to transition to the connection state with the originating modem.

At this time, the repetitive transmission process of 'ENQ', 'R', and 'M' data between the calling modem and the called modem should be performed within 750 ms. Otherwise, access is made according to CCITT rules.

After the remote diagnosis connection is made as described above, the remote diagnosis function is performed in the same manner as in FIG. 4. In this case, the operation procedure of the calling modem is the same as the general command sending process. However, the receiving modem should perform the remote diagnosis function. Therefore, when receiving the remote diagnosis command, it should be able to send the status data of the modem according to the command as in the fourth method.

First, the receiving modem recognizes this at step 401 when receiving data through the circuit control unit 110 and analyzes the received data at step 402.

At this time, since the originating modem and the terminating modem have the AT command system as shown in Table 4, the first communication between the modems should be character data of 'A' and 'T'. Therefore, when the AT command is generated from the DTE of the calling modem, it is applied to the DTE connecting portion 80 of the calling modem through the RS-232C cable, and the DTE connecting portion 80 receives the AT command of the received RS-232C level to the TTL level. After conversion, it is applied to the communication unit 90.

Then, the central processing unit 10 reads and analyzes the contents of the reception buffer of the communication unit (Universal Asynchrous Receiver & Transmitter: UART) 70, and applies it to the modulation / demodulation unit 30, and the modulation / demodulation unit 30 is the central processing unit ( After the data compression and modulation under the control of 10) is converted into an analog signal and output to the rotation controller 40. The line controller 110 then outputs the received analog signal to a telephone line or a dedicated line.

Then, in the incoming modem, the circuit control unit 10 applies the received signal to the demodulation unit 100, and the demodulation unit 100 digitally converts the received analog signal, expands it to the original size with compressed data, and also inherently Demodulate the data to the communication unit 90. The central processing unit 10 then reads and analyzes the received data of the communication unit 90 and transmits the data to the DTE connection unit 80. At this time, when the central processing unit 10 detects the reception of the data in step 401 by the interrupt of the communication unit 90, in step 402, the data is read and analyzed from the communication unit 90. At this time, the AT command is used between the modems, and thus, the AT command is checked by performing steps (403) to (407).

If the received data is an AT command as described above, the AT command received is analyzed and then valid AT command is checked.

At this time, valid AT commands used between the modems are shown in Table 4 above. Therefore, if another command other than the AT command shown in Table 4 is received in step 411, error processing is performed in step 417, and the processing result is fed back to the calling modem in the reverse order of reception. However, if the AT command is valid in step 411, the AT command is checked for the remote diagnosis function in step 412. If the AT command is not the remote command, the AT command is checked in step 4118. Process and also performs step 406.

Here, among AT commands, AT commands that require the remote diagnosis function are 'AT & V' and 'AT＼S' in the above AT commands. Here, 'AT＼S' is a first diagnostic command, which displays the current operating state of the called modem in detail, and 'AT & V' is a second diagnostic command that indicates the current nonvolatile memory (Non-Volatile RAM) in the called modem. : Displays the contents and profile of S register in NVRAM. Therefore, when recognizing reception of the first diagnosis command 'AT'S' in steps 412 and 413, the central processing unit 10 determines the receiving modem as shown in Table 5 below in step 414. The current operation status is displayed.

TABLE 5

Here, each of the information shown in Table 5 represents the state information stored in the nonvolatile memory of the current incoming modem in the AT command system as shown in Table 4, and the current DIP switch unit 40 The status is displayed. Therefore, when the operator of the terminating modem incorrectly inputs an AT command to change the state information of the nonvolatile memory or when a specific switch of the DIP switch unit 40 is incorrectly positioned to perform a function, as shown in Table 5 above. It will appear in the table. At this time, the called modem outputs the information as shown in Table 5 to the communication unit 90 at step 416 and outputs the DTE through the DTE connection unit 80 and through the modulation / demodulation unit 100 and the rotation control unit 110. Send to the calling modem. Then, the originating modem can diagnose the state by receiving the state information of the remote assurance modem transmitted from the called modem. At this time, in the case of a minor defect due to an AT command or a DIP switch error that is not a fatal defect as described above, the defect may be resolved by calling the operator by telephone.

In addition, in the case of 'AT & V', which is the second diagnostic command through steps 412 and 413, in step 415, the contents and profile of the S register in the nonvolatile memory of the terminating modem as shown in Table 6 below. Display the value.

TABLE 6

Here, the contents of all S registers are represented by HEX values in decimal numbers and parentheses, and the functions of the S ₀ -S ₂₇ registers of Table 6 are as follows.

SO (Ring To Answer, 0-255): The value of this register is the number of rings to detect until auto answer.

S0 = 0 is not auto-responsive (default)

S1 (Ring Count, Read Only, 0-255): increases by 1 whenever the modem detects ring signal (initial value = 0)

S2 (Escape coded character, 0-255): Indicates the decimal value of the ACII value of the escape coded character.

Initial value: 43 (equivalent to "+")

S3 (Carriage Return character, 0-127): It represents ASCII value of carriage return character in decimal.

Initial value: 13 (CR)

S4 (Line Feed Character, 0-127): Indicates ASCII value of Line Feed character in decimal.

Initial value: 10 ("CTRL J")

S4 (Back space character, except 33-126 of 0-255): Indicates the ASCII value of the back space character in decimal format.

Initial value: 8 ("CTRL H")

S6 (Wait For Dialing, 2-255): Only when the modem does not detect dial tone (ATX0, ATX1, ATX3) after waiting off-hook for dialing.

Initial value: 2 seconds

S7 (Wait For Carrier After Dialing 0-255): The time to detect the carrier from the other modem before disconnecting the line.

Initial value: 30 seconds

S8 (Pause time, 0-255): Specify the waiting time of ",".

Initial value: 2 seconds

S9 (Carrier Detect Respond Time, 1-255): Used to adjust the time to detect and respond to the carrier.

Initial value: 6 (0.6 seconds), Unit: 0.1 second

S10 (Lost Carrier To Hang Up, 1-255): When the receiving carrier is not detected during the data transmission, the line is cut. Adjust the delay time from when the receiving carrier is not detected until the line is stopped.

If it is S10-255, it does not disconnect the line even though the receiving broadcast wave is not detected.

Initial value: 14 (1.4 seconds), Unit: 0.1 second

S11 unused

S12 (Escape Code Guad Time, 20-255:

Used to set the input interval time between escape code and escape code.

Initial value: 50 (1 second), Unit: 20 msec

S13 unused

S14 (meaning of each bit)

S17 unused

S18 (Test time):

This register is used to set the test period of AL, DL, RDL, etc., and can be from 1 second to 255 seconds. The test can be stopped at any time by running the & TO command. Initial value = 0

S19 unused

S20 unused

S21 (meaning of each bit)

S24 unused

S25 (DTR Delay Time):

Ignore changes in DTR if the on-off time of the DTR on-line is less than the value set in S25.

Initial value = 5 (50 msec, unit: 10 msec. (0-255)

S27 (meaning of each bit)

Thereafter, the originating modem transmits the stored information of the S ₀ -S ₂₇ register as shown in Table 6 to the originating modem in step 416. Then, the operator of the originating modem may analyze the stored information of the received S register and check whether there is an abnormality, and then call the operator of the terminating modem to notify it.

Therefore, when looking at the unattended diagnosis process of the remote modem, first, when the abnormal state of the remote modem occurs, call the system maintenance center to notify the abnormal state, and raise the DIP switch No. 10 of the remote modem. The system then attempts to connect to the modem by dialing it through the modem in the system maintenance center. At this time, the modem of the system maintenance center becomes the generating modem and sends out the training sequence signal when detecting the response tone to match the transmission speed with the other receiving modem. After generating the remote diagnosis request signal ENQ, the response signals 'R' and 'M' When receiving a signal, the remote diagnosis communication call is completed. In addition, the remote modem becomes a reliable modem and transmits a response tone when receiving an incoming ring signal, and transmits a training sequence signal after transmitting a response tone to match the transmission speed with the calling modem. After receiving the ENQ signal, it sends out the 'R' and 'M' signals in response to this, and terminates the process of establishing a diagnosis network.

Then, when the originating modem generates the remote diagnosis command 'AT＼S' or 'AT & V', the called modem analyzes the received modem AT command and then displays the status information as shown in Table 5 or Table 6, respectively. Send to outgoing modem. At this time, the incoming modem will beep, beep, beep when the maintenance is finished. Then, the operator of the incoming modem can confirm the diagnosis result by forming a telephone call with the operator of the calling modem when the [communication / charge] switch of the key panel 50 is pressed. In addition, the calling modem receives the status information as shown in Table 5 or Table 6 transmitted from the called modem, and analyzes AT command status, DIP switch status, S register status information, and the like. The status can be analyzed and the operator can directly maintain the remote status for abnormal conditions caused by immature operation.

After performing the above remote diagnosis function, the DIP switch No. 10 should be lowered. This is because normally, if the DIP switch No. 10 is placed up, a remote diagnosis communication path such as the third system is formed, which increases the modem connection time.

As described above, it is possible to check the operation status of remotely spaced modems without a visit of maintenance personnel, and in case of an abnormal condition, perform modem communication with remote modems at a specific location and perform abnormal state analysis and maintenance of the corresponding modem. There is an advantage to that.

Claims (7)

A method of remotely diagnosing a modem by connecting a remotely spaced modem to a modem of a maintenance center, the method comprising: attempting a modem connection between an outgoing modem of the maintenance center and an incoming modem of a remote site; Transmitting a signal, the receiving modem performing a modem connection operation of a remote diagnosis function in response to the remote diagnosis request signal, and receiving and transmitting a remote diagnosis command received by the calling modem to the receiving modem; Receiving and analyzing the remote diagnosis command of the incoming modem, tabulating the status information of another modem in the corresponding command, and transmitting the same to the calling modem; and displaying status information of the receiving modem. The maintenance data received according to the diagnosis result of the received information is sent to the receiving modem to Remote diagnostics of the modem method of claim constituted by any process, which maintains the call modem. 2. The method of claim 1, wherein in the process of connecting a modem with a remote diagnosis function, the originating modem transmits a remote diagnosis request signal to the called modem, and in response to the remote diagnosis request signal from which the called modem is received. Transmitting a response signal to the calling modem, completing a modem connection operation of a remote diagnosis function, and checking whether a calling signal is received within a predetermined time after the calling modem transmits the remote diagnosis request signal, and responding within a predetermined time; A method for remote diagnosis of a modem, comprising: completing a modem connection operation of a remote diagnosis function only upon receiving a signal. 3. The method of claim 2, wherein the receiving modem transmits remote diagnosis information to the calling modem by analyzing a type of diagnosis according to the command when receiving a diagnostic command from the calling modem. Transmitting a table of the current operating state of the modem and current position information of the switch to the calling modem, and tabulating the information of the current nonvolatile memory of the second diagnostic command date and time to the calling modem in the analyzing process. Remote diagnostic method of the modem, characterized in that consisting of a process. A method of remotely diagnosing a modem at a remote location by using a modem of a maintenance center as a calling modem, the method comprising: waiting for a response tone to be received from a receiving modem at a remote place after dialing the dial-up modem; Matching the connection speed with the called modem to send a signal, transmitting a remote diagnosis request signal after matching the connected speed, checking whether a response signal is received, and answering the response signal from the called modem in the checking process. A method of diagnosing a modem, comprising receiving a remote diagnostic function upon completion of a modem connection. The method of claim 4, wherein the remote diagnosis request signal comprises an odd parity remote diagnosis request signal and an even parity remote diagnosis request signal. 6. The method of claim 4 or 5, wherein the modem connection process performs a modem connection of a remote diagnosis function only when a response signal is received within a predetermined time after the remote diagnosis signal is transmitted. A method of remotely diagnosing a modem of a remote site by using a modem of a maintenance center as a calling modem, wherein the receiving modem responds by dialing the calling modem, and after the procedure is performed, the calling modem and the receiving modem Transmitting a training sequence signal to match a connection speed, transmitting a request signal remote from the originating modem to the called modem, and sending a response signal to the calling modem when the called modem receives the remote diagnosis request signal. Transmitting and completing a remote diagnosis modem connection; completing a remote diagnosis modem connection when the calling modem receives a response signal from the called modem within a predetermined time; and the remote diagnosis modem connection unit and the remote receiving modem. Sending a diagnostic command to the terminating modem; After analyzing the remote diagnostic command received from the new modem, and the status information of the receiving modem according to the diagnostic function to the table to send out to the calling modem, the status information of the receiving modem remotely separated from the calling modem A diagnostic method of a modem, characterized in that it is operable to diagnose.