JPH0787477B2 - Communication control device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a communication control device.

[Prior art]

Conventionally, there is a method of communicating data from a personal host such as a personal computer or a word processor using a telephone line. In this case, when the other party is facsimile, transmission delay may occur.

〔Purpose〕

The present invention is intended to eliminate the above inconvenience, and stores data received from a first terminal according to a first communication procedure and stores the stored received data according to a second communication procedure. When transmitting to another terminal, the first communication procedure sets the first data transmission rate, which is the data reception rate from the first terminal, and the second communication procedure is executed according to the first data transmission rate. Then, the second data transmission rate, which is the data transmission rate to the second terminal, is set to be equal to or lower than the first data transmission rate, and the first and second communication procedures are performed according to the stored data amount. By performing
Even if the communication procedure of receiving data from the terminal and transmitting the data to the second terminal are different, the data can be properly received and transmitted.

For example, it is effective when communicating the code data of the host using the facsimile procedure. In this case, the code data is converted into bit data of the image and transmitted to the facsimile. If the other device is a personal computer, etc., the communication procedure for personal computer communication and word processing communication is selected from the ROM and communication is executed. In this case, the code data is sent without the format conversion of the data.

〔Example〕

FIG. 1 is a conceptual diagram of this system. 1 is the host section,
It is connected to the communication function section 3 and the cable 2. The host transfers the control command and the image data to the communication function unit 3 and transmits the image to the partner FAX via the public telephone line 4 of FIG. The image data from the host uses MH compressed image data. The communication function part of 3 consists of a protocol and a modem to support the T.30 procedure, and an NCU part.
3 Has the function of facsimile transmission. Further, the communication function unit 3 is provided with a call unit (not shown). When the handset 6 is connected to the communication function unit 3 and the host is not connected to the communication function unit 3, the CPU of the communication function unit 3 detects that the host is not connected. Switch the NCU relay to the call side to operate as a telephone.

Further, the CPU of the communication function unit 3 switches the relay of the NCU unit to the communication unit side based on the switching instruction by the changeover switch (not shown), and enables the communication by the handset 6. That is, the communication function unit 3 operates as a telephone in the same manner as when the host is not connected.

The normal sequence of an automatic incoming / outgoing call by the G3 facsimile binary procedure will be described with reference to FIG. The left side is the calling side and the right side is the called side. The calling side sends a CNG (calling tone) when the other party is connected after calling the other party by a dial signal. When the called party responds, it sends a CED (Called Station Identification) Tonal signal.

Then, the called side sends a binary signal of DIS (digital identification signal) to present the communication conditions. It is stipulated that the called side continues to send again for 30 to 40 seconds after 3 seconds until the calling side sends DCS (digital command signal) for the DIS signal.

The calling side sends a DCS signal according to the contents of DIS, sets the communication speed and specifications, sends training and data, and checks whether the called side can receive correctly.

The called side returns a CFR (reception preparation confirmation) binary signal if it can receive correctly. If it cannot be received, it returns an FTT (training failure) binary signal, starts from DCS again, and lowers the transmission rate if necessary. If the calling side does not transmit the image signal within 6 seconds after receiving the CFR, the line is disconnected as an error, so the communication function must receive the image data from the host at this point. CCITT
According to T.4, MH or MR is used as an image signal in G3 fax
The compression method is called. Normally, MH compression is performed and EOL (line end code) is added to each line. In addition, the minimum transmission time of one image line is determined by DIS, DCS, 0,
The values of 5,10,20,40, mesc are set. Similarly, since the maximum transmission time for one line is specified as 5 seconds, if the data transfer rate from the host is slow, a file (continuous 0) is put between the data and EOL and waits. However, since there is little delay in data in the past, even if the product is commercialized, inserting a long file will cause an error and insert the previous data due to a line error, or the drive of the paper feed motor will be stopped and the image will not be displayed properly. It is often continuous. Therefore, it is not possible to slow down the transmission speed by inserting a file.

The end of the image data, θ in the figure indicates EOM (end of message) MPS (multi-page signal), EOP (end of procedure)
Of each binary signal. In the case of EOP, the called side sends MCF (message confirmation) and the calling side sends DCN (disconnect command) to disconnect the line.

If more images are sent under the same conditions, the next page data will be sent within 6 seconds after sending MPS and receiving MCF. EOM is another condition, and if you want to send more images, you will return to the procedure from the first DIS.

FIG. 3 is an example of the sequence of the system of the present invention. The personal computer and the communication function section are RS232C interfaces, and asynchronous serial signals are used. The commands and transmission control conform to the recommended communication method for personal computer communication devices (hereinafter referred to as JUST-PC procedure) announced by the Japan Post 1984. Except for commands that start with L (except LRS), they are exactly the same. Initially, the communication function block is initialized by the LMD command containing the local telephone number and user ID, and the communication function block responds with an LRS. Next, use the CNR command to enter the telephone number in the parameter section and make a call.

When the partner FAX is connected, the communication function unit sends an RNC confirmation signal to the host side and simultaneously sends CNG to the partner FAX. Opponent fax
When DIS is received next to CED, the communication function unit sends DI to the host.
Receive the contents of S by the communication signal of LRA. The host uses the LPT command, which includes the encoding method, recording width, recording length, maximum transmission rate, resolution, and page resendability, for DCS information in accordance with DIS (where the transmission speed can be arbitrarily selected according to the own modem performance). However, if the speed is lower than the data transmission speed between the host and image error or underline occurs, read the speed designation information between the host and the communication function and set a value less than that.
Must be the content of S. In a system that cannot be read as information, the LRS compatible transmission rate for the LMD may be measured. ) Send to the communication function section. LPT also invites confirmation of the previously sent page. For the first LPT, the LRS response is returned without parameters. After this, the host sends image data to the parameter section one after another with a CDT (data transmission command) command. The communication function block inserts a file due to lack of data from the host when the internal buffer stores more than a predetermined amount of data, or after checking the LPT command reception for sending the next page and then proceeding with the sequence below DCS. And prevents underrun.
When the host finishes sending the image data, it will send the data one after another after the LPT command. The communication function section
After sending the image signal, the next page data amount in the internal buffer is checked as described above. If it is less than a predetermined value, EOM is output and if enough is stored, the image signal is continuously sent by MPS. The final page is notified to the communication function by the LDE (data end command) signal following the image data from the host. LIC parameter for the second and subsequent LPT commands, PIC = 0
Means MCF, and PIC = 1 means RTN (reception failure notification). When PIC = 1, if there is a retransmission capability declaration in the LPT, it is possible to interrupt the image data transmission (CDT) again after the LPT even while sending the next page. DI for RTN
Since it is specified to start from S, the data delay of the host will be saved as well. Approximately 2K bytes is desirable as a buffer.

〔The invention's effect〕

As described above, according to the present invention, even when the first communication procedure for receiving data from the first terminal and the second communication procedure for transmitting the received data to the second terminal are different, The first and second communication procedures are performed so that the data transmission speed to the second terminal is less than or equal to the data reception speed from the first terminal, and Since the first and second communication procedures are executed according to the stored data amount, it is possible to prevent the underrun or fill data from being overfilled.

[Brief description of drawings]

FIG. 1 is a conceptual diagram of a system of the present invention, FIG. 2 is a sequence diagram after connection of a G3 facsimile system to a telephone network, FIG. 3 is a sequence diagram of the present invention, and FIG. 4 is a sequence flow chart diagram focusing on communication functions. Is.

Claims (1)

[Claims] 1. A communication control device for receiving data from a first terminal and transmitting the received data to a second terminal, wherein the first data transmission rate is set in accordance with a first communication procedure. Receiving means for receiving data from the terminal, storage means for temporarily storing the data received by the receiving means, and data in the storage means at a second data transmission rate set according to a second communication procedure. Transmitting means for transmitting to the second terminal, and transmitting a signal of the second communication procedure to the second terminal based on a signal received from the first terminal in the first communication procedure. A signal of the first communication procedure is sent to the first terminal based on a signal received from the second terminal in the second communication procedure to transmit the first and second signals.
Communication procedure executing means for executing the communication procedure of, and the communication procedure executing means sets the first data transmission rate according to the first communication procedure, and sets the first data transmission rate according to the set first data transmission rate. The second communication procedure is executed to set the second data transmission rate to be less than or equal to the first data transmission rate, and the first and second communication procedures are performed according to the amount of data in the storage means. And transmitting the data to the second terminal while receiving the data from the first terminal.