JPH1093609A - Host computer and network device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To execute data communication without delay even at the time of the congestion of a LAN by returning a connect command to an application program in advance before sending an input-output request in a host computer which is connected to a local network LAN so that it can communicate. SOLUTION: A PC 2 receives a connect command from a network 1 and a frame from a FAX 4 on the other side, and issues a request command like CSI, etc., apart from an NSF frame in a prescribed procedure. In such cases, when the network device 1 receives a command from an application program, it immediately returns it to the application program and the PC 2 cancels the connect command at that time, before the PC 2 receives a real connect command. Thereby, the device 1 can smoothly communicate with the application program of the PC 2 without being influenced by delay that is brought about by the congestion which occurs on a LAN 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to EtherNE.
The present invention relates to a host computer communicably connected to a local area network such as T, and a network device communicably connected to the host computer via the local area network.

[0002]

2. Description of the Related Art Conventionally, a host computer and a network device are connected via a LAN such as EtherNET so as to be able to perform data communication, and a PSTN is connected to the network device.
There has been a network system that enables facsimile communication with a terminal device such as a facsimile device connected via the Internet.

[0003] In addition, the mobile telephone comprises a master unit connected to the PSTN and its slave unit. The slave unit has a built-in data communication modem and converts it into a control command in accordance with a modem signal, thereby controlling functions of the telephone. (For example, see Japanese Patent Application Laid-Open No. Hei 7-154501).

[0004]

However, in the above network system, for example, EtherN
In data communication between host computers on a LAN such as ET, congestion occurs almost inevitably, and data packets to be transmitted are lost or packet transmission is delayed. Real-time could not be guaranteed.

[0005] Therefore, a modem of a host computer such as a personal computer (PC) called an AT modem is usually used in a one-to-one connection using an RS232C cable. Delay in data communication hardly occurs.

However, when the AT modem is connected via a LAN instead of an RS232C cable, the above-described congestion occurs, so that there has been a problem that it is impossible for the host computer to determine the timing.

The present invention has been made in view of the above points, and has as its object to enable a host computer on a LAN to perform data transmission without delay even when congestion occurs.

When facsimile reception is performed between the AT modem and the host computer, the received image information is usually confirmed on the host computer. At that time, if an error is found in the received image, the host computer issues an error processing request. However, when the host computer and the modem are connected via the LAN, there has been a problem that the error processing request is delayed due to the occurrence of the congestion described above.

Therefore, the present invention checks image information in a modem of a network device on a LAN,
It is another object of the present invention to perform processing without waiting for an error processing request from a host computer.

[0010]

According to the present invention, in order to achieve the above object, a host computer connected to a local area network so as to be able to perform data communication receives an input / output request to a COM port by an application program to be executed. When redialing to the area network, means for returning a CONNECT command to the application program before the input / output request is sent is provided.

In a network device communicably connected to the host computer via a local area network, means for communicatively connecting to a public telephone network, and an AT transmitted from the host computer via the local area network. + Of commands
Means for ignoring the FTS command may be provided.

Further, in a network device communicably connected to the host computer via a local area network, means for continuously flowing a FILL bit in an MH portion in image information transmitted from the host computer via the local area network. Should be provided.

Further, in a network device communicably connected to the host computer via a local area network, when receiving a facsimile from a terminal device via the public telephone network, the image information received by the facsimile is transmitted to the local area. It is preferable to provide a means for transmitting the data to the host computer via the network and simultaneously decoding and checking the data.

According to a first aspect of the present invention, there is provided a host computer having a CO program executed by an application program.
When redialing an I / O request to the M port to the local area network, a CONNECT command is returned to the application program before the I / O request is sent, so that the CONNECT command is immediately returned to the application program. The application program of the host computer can transmit the next frame of data without delay. Therefore, the host computer on the LAN can transmit data without delay without being affected by congestion.

Further, the network apparatus according to the second aspect of the present invention ignores the + FTS command among the AT commands transmitted from the host computer. = 8 commands can be processed,
It is possible to eliminate a delay in processing time due to congestion occurring on the LAN.

Further, in the network device according to the third aspect of the present invention, since the FILL bit is continuously flown in the MH portion of the image information transmitted from the host computer, the network device communicates with the facsimile transmission source terminal device in the FILL bit portion of the MH. Timing can be controlled, and image information can be transmitted without delay even if there is a packet transmission delay from the host computer due to congestion occurring on the LAN.

Further, in the network device according to the present invention, when receiving a facsimile from the terminal device, the facsimile-received image information is transmitted to the host computer and simultaneously decoded and inspected. An error in image information can be detected without waiting for an instruction, and even if an instruction from the host computer is delayed due to congestion occurring on the LAN, facsimile reception from the terminal device can be performed without delay.

[0018]

Embodiments of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a diagram showing a configuration of a network system to which a network device according to an embodiment of the present invention is connected.

In this network system, a network apparatus 1 such as a facsimile apparatus according to the present invention and a host computer (PC) 2 are connected so as to be able to perform data communication via a local area network (LAN) 3. The PC 2 is a client device of the network device 1 and includes a microcomputer such as a CPU, a ROM, and a RAM, and functions as a host computer of the present invention. Further, it issues an AT command to the network device 1 to execute a function relating to the present invention.

The network apparatus 1 functions as a network apparatus of the present invention, and is connected to a facsimile apparatus (FAX) 4 via a public telephone network (PSTN) 5 so as to be capable of facsimile communication. FAX opponent machine.

FIG. 2 shows the network device 1 shown in FIG.
FIG. 3 is a diagram showing a main configuration of FIG. This network device 1
Has a built-in microcomputer, CPU 10, RA
M11, ROM12, local area network (L
AN) controller 13, transformer 14, modem 15,
It comprises functional units such as a network control unit (NCU) 16, a compression / decompression unit (DR) 17, and a timer 18.

The CPU 10 controls the entire network device and executes processes related to the present invention.
The RAM 11 is a readable and writable memory that is a working memory when the CPU 10 performs various processes. The ROM 12 is a read-only memory that stores various programs executed by the CPU 10 and processing programs related to the present invention.

The LAN controller 13 controls the physical layer and the data link layer of the LAN 3, and controls the LAN 3
The detection of congestion is also performed. The transformer 14 is used for isolation. The modem 15 sends a digital signal to the PSTN 5, modulates the digital signal into an analog signal, and demodulates the digital signal from the analog signal modulated by the other party. The NCU 16 is an interface for connecting to the PSTN 5. The DR 17 expands the compressed FAX image information. The timer 18 measures time.

That is, the LAN controller 13 and the transformer 14 of the PC 2 function as means for connecting the LAN 3 so as to be capable of data communication, and the CPU 10 of the PC 2
Etc. by the application program to be executed
When an input / output request to the M port is redialed to the LAN 3, it functions as a means for returning a CONNECT command to the application program before the input / output request is sent.

The modem 1 of the network device 1
5, NCU 16 and the like function as means for communicatively connecting to FAX 4 via PSTN 5, and CPU 10 or the like of the network device ignores + FTS command among AT commands transmitted from PC 2 via LAN 3. Perform the function.

Further, the CPU 1 of the network device
0 means means for continuously flowing the FILL bit in the MH part in the image information transmitted from the PC 2 via the LAN 3;
When a facsimile is received from the facsimile machine 4 via the TN 5, the image information received by the facsimile machine is transmitted to the PC
2 and simultaneously performs the function of decoding and checking.

FIG. 3 is a diagram showing the configuration of the driver of the PC 2 shown in FIG. PC2 has a COM driver I /
F, a redirector, a COM driver, a LAN protocol I / F, a LAN protocol, a LAN driver, and other drivers. The redirector receives a command from the application program via the COM driver I / F.
A process of intercepting data passed to the M driver and passing the data to the LAN driver is performed.

FIG. 4 is a diagram showing the procedure from PC2 to FAX4 shown in FIG.
It is a flowchart which shows the data processing to the. In the PC 2, an AT command from the application program to the modem on the COM port is passed to a protocol for controlling the protocol of the LAN 3 by a process (redirector) for redirecting the COM port.

The process for controlling the protocol of the LAN 3 is performed by the LA 3 on the network device 1 via the LAN 3.
It communicates with a process that controls the N3 protocol, and passes an AT command from an application program to the network device 1.

The process of controlling the protocol of the LAN 3 of the network device 1 uses the FAX data (image information) from the AT command passed through the LAN 3 as F
Passes to the process that controls the AX protocol and sends the fax
The process for controlling the protocol facsimile-transmits FAX data to FAX4.

FIG. 5 is a flow chart showing a facsimile reception process from the FAX 4 by the PC 2 shown in FIG. This processing corresponds to claim 4 of the present invention.
This is processing related to. The network device 1 has a FAX 4
FAX data (image information) from PC to PC2
The FAX data is passed to a decoding process by the DR 17 to be decoded.

In this way, the network device 1
Even if there is an error in the image information from the FAX 4, it is possible to determine that the error has occurred without waiting for an instruction from the PC 2, and perform an appropriate process for the error.

FIG. 6 shows the network device 1 shown in FIG.
FIG. 6 is a diagram showing a communication protocol when facsimile transmission is performed from the PC 2 to the FAX 4 via the PC 2. This communication protocol is a facsimile transmission protocol when the modem 15 of the network device 1 is an AT modem and the AT modem and the PC 2 are connected by an RS232C cable.

(1) First, the PC 2 issues an AT + FCCLASS1 command to the modem 15 of the network device 1, and designates the modem 15 to be in the FAX4 CLASS1 mode. The modem 15 returns OK to the PC 2 to notify that the command has been normally processed.

(2) Next, the PC 2 is connected to the network device 1
ATDTxxxx (this “xxxx” is a telephone number) to the modem 15 of the
Issuing TDPxxxx and faxing the destination called party
Specify the telephone number of 4. (3) On the other hand, the modem 15 of the network device 1 calls the fax 4 of the other party, and then waits for a CED or HDLC flag while outputting a CNG tone.

(4) Modem 15 of Network Device 1
PC2 is detected when either CED or HDLC is detected.
And returns a frame from the other party at the same time. In this case, since there is an NSF, the NSF is returned. Then, at the end of the frame, <DLE><ETX>
And return OK.

(5) The PC 2 issues an AT + FRH = 3 command to request CSI or the like in addition to the received NSF frame. Hereinafter, communication is performed according to the sequence shown in FIG.

FIG. 7 is a diagram showing a communication protocol of the network system shown in FIG. Network device 1
Needs to distinguish between an application program and a driver in the PC 2.

Normally, when an error such as congestion on the LAN 3 does not occur, the communication protocol shown in FIG. 6 is executed, so that the driver passes the command from the application program to the network device 1 as it is.
The frame returned from the network device 1 is passed to the application as it is.

FIG. 8 is a diagram showing a communication protocol according to claim 1 of the present invention in the network system shown in FIG. When the network device 1 normally detects the flag of the transmission frame from the facsimile machine 4, the AT + FRH =
Issue a CONNECT command for 3 commands.

However, the CONNECT command may be passed to the PC 2 with a delay due to congestion occurring in the middle of the LAN 3. If the delay is passed to the application, the processing is further delayed, and the protocol with the FAX 4 is finally established. No longer.

Therefore, the network device 1 establishes a CONNECT when the PC 2 issues the AT + FRH = 3 command.
The T command is sent to the network device 1
When a command is received from the application program before a real CONNECT command is received from the application program, the command is immediately returned to the application program.

Then, the PC 2 discards the CONNECT command from the network device 1 at that time. In this way, the network device 1 can smoothly communicate with the application program of the PC 2 without being affected by the delay due to the congestion that has occurred on the LAN 3.

The same processing is performed not only when the application program of the PC 2 receives a frame from the FAX 4 but also when transmitting a frame to the FAX 4. That is, the network device 1 usually
When a T + FTH = 3 command is received, a CONNECT command is returned at the timing of sending the HDLC flag. However, if the CONNECT command is delayed, the sending timing of the next frame changes.

Therefore, in the case of AT + FTH = 3 command, the command is immediately returned to the application program upon receiving the command from the application program before receiving the true CONNECT command in the same manner as the above-described processing.

Then, the CONNECT command from the network device 1 at that time is discarded. In this way, the network device 1 can smoothly communicate with the application program of the PC 2 without being affected by the delay due to the congestion that has occurred on the LAN 3.

FIG. 9 is a diagram showing a communication protocol according to claim 2 of the present invention in the network system shown in FIG. In this communication protocol (FAX protocol), 75 ± is used during the transition from the DCS frame to the next TCF frame, and until the transmission of the image information (PIX) and the transmission of the EOP frame (the same applies to the EOM frame). It is necessary to wait for 20 msec.

The AT modem satisfies the above-mentioned requirement of 75 ± 20 msec by issuing an AT + FTS = 8 command and performing a wait processing of 80 msec. Note that “8” in the AT + FTS = 8 command indicates 80 msec, and a value other than 8 is possible.

However, in the network device 1,
AT + FTS = 8 command is delayed by the influence of congestion on LAN3, and AT + FT from PC2 is kept as it is.
When S = 8 command is executed, command request time 8
In addition to 0 msec, a time delayed due to the influence of congestion is added.

Therefore, the network device 1
8, the time from the transmission of the DCS frame or the transmission of the PIX is measured, and the delay time for the delayed AT + FTS = 8 command is obtained based on the time measured by the timer 18.

In this way, the network device 1
Even if the AT + FTS = 8 command from the PC 2 is delayed due to the influence of the congestion on the LAN 3, it can be correctly processed. Note that the measurement of the time may be substituted by the processing of the CPU 10 itself.

FIG. 10 is a diagram showing a communication protocol according to claim 3 of the present invention in the network system shown in FIG. In this communication protocol, when transmitting the image information (PIX) from the PC 2 to the FAX 4, the network device 1 uses the K parameter if the image information is encoded by MH or if it is encoded by MR for each line. It is transmitted as one packet for each specified line.

In the case of MH, for example, if PIX (3) is delayed due to the effect of congestion, PIX (3) will be delayed until PIX (3) arrives.
The FILL bit of (2) is continuously transmitted. In this way,
The network device 1 can transmit the image information to the FAX 4 of the other party without delay even if the PIX (3) from the PC 2 is delayed.

In the case of MR, for example, PIX (3)
Is delayed due to the congestion, the FILL bit is continuously transmitted in the MH portion of the first row of PIX (2) until PIX (3) arrives. When PIX (3) arrives, FIL
The transmission of the L bit is stopped, and the remaining MR portion is transmitted.
In this manner, the network device 1 can transmit the image information to the FAX 4 of the other party without delay even if the PIX (3) from the PC 2 is delayed.

As described above, PC2 is connected to CONNECT.
Since the T command is immediately returned to the running application program, the application program can transmit the next frame without delay,
When data is transmitted to the LAN 3, the data is not adversely affected by the congestion on the LAN 3.

The network device 1 measures the time at the original timing and calculates AT + FTS = 8 from the PC 2.
Since the command is processed, the command from PC2 is LA
Even if the processing is delayed due to the congestion on N3, the processing time is not affected.

Further, when facsimile transmitting the image information transmitted from the PC 2 to the FAX 4, the network apparatus 1 controls the timing of the FAX 4 of the MH with the destination FAX 4. The transmission of the image information to the FAX 4 can be performed without delay even if the transmission of the packet from the FAX 4 is delayed.

Further, the network apparatus 1
When the facsimile is received from the X4, the image information is sent to the PC 2 and the decoding is performed at the same time, so that the error of the image information received from the FAX 4 can be immediately checked.
An error in image information can be detected and dealt with without waiting for an instruction from C2. Therefore, the FAX 4 is not affected by the delay of the instruction from the PC 2 due to the congestion on the LAN 3.
Error handling at the time of facsimile reception from can be performed quickly.

[0059]

As described above, according to the host computer of the present invention, even if congestion occurs on the LAN, data transmission can be performed without delay. Further, according to the network device of the present invention, it is possible to eliminate the processing time delay due to the congestion occurring on the LAN. Further, by confirming the image information in the modem on the LAN, processing can be performed without waiting for an error processing request from the host computer.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a network system in which a host computer and a network device according to an embodiment of the present invention are connected.

FIG. 2 is a diagram illustrating a configuration of a network device illustrated in FIG. 1;

FIG. 3 is a diagram illustrating a configuration of a driver of the host computer illustrated in FIG. 1;

4 is a flowchart showing data processing from the host computer shown in FIG. 1 to a facsimile.

FIG. 5 is a flowchart showing a process of facsimile reception from a facsimile via the network device by the host computer shown in FIG. 1;

FIG. 6 is a diagram showing a communication protocol when facsimile transmission from a host computer to a facsimile via the network device shown in FIG. 1;

FIG. 7 is a diagram showing a communication protocol of the network device shown in FIG. 1;

FIG. 8 is a view showing a communication protocol according to claim 1 of the present invention in the network system shown in FIG. 1;

FIG. 9 is a diagram showing a communication protocol according to claim 2 of the present invention in the network system shown in FIG. 1;

FIG. 10 is a diagram showing a communication protocol according to claim 3 of the present invention in the network system shown in FIG. 1;

[Explanation of symbols]

1: Network device 2: Host computer (PC) 3: Local area network (LAN) 4: Facsimile device (FAX) 5: Public telephone network (PSTN) 10: CPU 11: RAM 12: ROM 13: Local area network (LAN) ) Controller 14: Transformer 15: Modem 16: Network control unit (NCU) 17: Compression / decompression unit (DR) 18: Timer

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Claims (4)

[Claims] 1. A host computer connected to a local area network for data communication, when redialing an input / output request to a COM port by an executed application program to the local area network, before the input / output request is sent. Connect to the application program in advance
A host computer comprising means for returning a command. 2. A network device for communicatively connecting to a host computer according to claim 1 via a local area network, means for communicatively connecting to a public telephone network, and from a host computer via said local area network. A network device comprising means for ignoring a + FTS command among transmitted AT commands. 3. A network device communicably connected to the host computer via a local area network according to claim 1, wherein a FILL bit is set in an MH portion in image information transmitted from the host computer via the local area network. A network device provided with a means for continuing the flow. 4. A network device communicably connected to a host computer according to claim 1 via a local area network, wherein when facsimile is received from a terminal device via the public telephone network, the image information received by facsimile is transmitted. A network device, further comprising means for transmitting to the host computer via the local area network and simultaneously decoding and checking.