JPS59117357A - Data transmitter - Google Patents

Abstract

PURPOSE:To realize a transmitter having a large data transmission speed by a conventional 8-bit microprocessor by dividing largely the transmitter into two functional blocks based on a protocol subject to hierarchy. CONSTITUTION:A communication controller 1 consists of units 11 and 12, and the conventional 8-bit microprocessor 11b performs transmission control in the unit 11 based on the high level data link control procedure being a link layer protocol. Further, the conventional 8-bit microprocessor 12a of the unit 12 executes the control of transport layer, session layer and document layer.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to a data transmission device.

[Prior art]

In general, data transmission equipment establishes data transmission procedures to improve data transmission reliability and transmission quality, and then sets higher-level protocols to layer the protocols to achieve various transmission functions. are doing.

In recent years, standards for G4 facsimile, which transmit image information faster than G3 facsimile, have been established by the CCITT (Consultative Committee for International Telegraph and Telephone). It has a transmission speed (48 to 64 kbps) and a layered protocol similar to Tenx (word processor with data communication function).

CCU (communication control unit) applied to G4 facsimile
If an attempt is made to realize this using a single general-purpose 8-bit trichrome processor, similar to that of the G3 facsimile, the transmission speed cannot reach a predetermined speed. Therefore, the CCU for G4 facsimile must have a different configuration, such as a bit slice type microprocessor (bipolar), but such a CCU has the disadvantages of high cost and complicated software design in accordance with the protocol. .

〔the purpose〕

An object of the present invention is to provide a data transmission bag that eliminates the above-mentioned disadvantages by clearly dividing the device into two functional units based on a layered protocol.

〔composition〕

Embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows an embodiment of the invention. This embodiment uses CCU (communication control unit) 1 for G4 facsimile.
It consists of a transmission control and data network interface circuit (compliant with CCITT Recommendation
11a, and a unit 12 that decodes the received data output from this unit 11 to create document data and control data, and also forms transmission data with a header to be described later and transfers it to the unit 11. It consists of

In the figure, llb and 12a are CPUs (central processing units) consisting of general-purpose 8-bit microprocessors;
ie, 12b is RAM (random access memory), lid, 12c is ROM (read only memory), lie, llf, 12d and 1.2e are I10 circuits, 12f stores document data of a predetermined number of frames. data memory.

The above-mentioned interface circuit 11a is the I10 circuit 11
connected to CPU 1 l b via e, CPU 11
b and the CPU 12a exchange control signals with each other. The data between unit 11 and unit 12 is I10
The control data DC is transmitted via the circuit 11f and the I10 circuit 12d, and the I10 circuit 12e exchanges control data DC with an external control device (for example, an SCU described later) (not shown).

However, the transmission terminal T1 of the interface circuit 11a, the control terminal C, the display terminal I, and the reception terminal R are connected to a DC terminal (not shown).
It is connected to the digital line network via E (data line termination equipment).

FIG. 2 shows an outline of the G4 facsimile machine.

As mentioned above, this G4 facsimile machine is a data network facsimile machine whose transmission speed is 48 to 64 kbps.

In the figure, 2 is a scanner that scans the image of the transmission original and converts it into two corresponding signals, 3 is a printer that outputs the received image, and 4 is a code converter for the image signal output from the scanner 2 and converts it into transmission data DT. DCR (code conversion unit) that converts (decodes) the received data added from CCU 1 into the original image signal;
, SCU that controls printer 3 and DCR 4
6 is this G4-face circuit.

The data transmission protocol of this G4 facsimile machine is layered as shown in FIG. In the figure, the link layer (data link level and network level protocols) LP is the protocol from call setup to network establishment, and the transport layer (transport level protocol) LP2 is the protocol used after the network is established. The session layer (session level protocol) LP3 is a protocol at the stage up to establishing a communication channel (through control according to the line type), and transmits data after mutually confirming the functions of the terminals (e.g. paper size, transmission speed, etc.) The protocol at the stage up to setting the mode and the document layer (document level protocol) LP4 are the protocols at the information transmission stage, and the link layer LP1. The upper protocols are transport layer LP2, session layer LP3, and document layer LP4 in this order.

In the CCU 1 shown in FIG. 1, the link layer LP.

Control of the transport layer LP2, session layer LP3, and document layer LP4 is realized by the unit 2.

FIGS. 4(a) to 4(d) show the format of transmission data in each layer.

Figure (a) shows a case where CCU 1 executes control of the link layer LP, that is, after calling the partner station, the HDLC
The figure shows the formation of transmission data that the CCU 1 sends to the digital line network during the process of establishing a data link with the other station based on the procedure. The transmission data in this case is the start flag sequence (01111110) FL, 7 address fields FLz, fl+lIm fields FL3, CR
It consists of C data (flag check seedance) FL and termination flag sequence (01111110) FL5, and constitutes a frame for monitoring and controlling the HDLC procedure that does not include an information field.

In the same figure (b), CCU 1 is the transport layer LP
2, that is, the formation of transmission data to be exchanged with the other station when establishing a communication path after establishing a data link. Transport information T(D) is control information in the transport layer LP2, and is subjected to frame processing in the HDLC procedure and converted into transmission data.

171 (c) ii: indicates the format of transmission data when the CCU 1 sets the session layer LP3, that is, the transmission mode between terminals (in this case, between G4 facsimile terminals). In this way, the session information DS consisting of terminal function information, business content display function, etc. includes the session header HD2, which is control information in the session layer LP3, the above-mentioned transport head HD,
is attached, and further subjected to framing processing using the HDLC procedure to be converted into transmission data.

In the same figure (d), CCU 1 is the document layer LP4
That is, it indicates the format of transmission data when transmitting facsimile image information. After the facsimile image information obtained by the scanner 2 is encoded by the DCR 4, it is transferred to the CCU 1 as transmission data DT, and the facsimile image information is transmitted to the CCU 1 at a predetermined number of 13 (2048
The data is divided into frames of octet unit (bit t) and sequentially stored in the data memory 2f for each frame. The document l-information DD shown in this figure is the transmission data DT for one frame stored in the data memo IJ 12f, the document header HD3 which is the control information in the document 1 to layer LP4, and the To the transport, ``HD'' is added, and ``H'' is added.
Framing processing of the DLC procedure is performed and the data is converted into transmission data.

FIG. 5 shows an example of the transmission flow between the G4 facsimile machines shown in FIG. This transmission flow consists of three phases: a call setup phase, a data transfer phase, and a call disconnection phase.

The unit 11 of the CCU 1 connects each terminal T, C of the interface circuit 11a during the call setup phase.

It controls I and R to physically connect the DCE and facsimile machine, and also sends dial information to the called station using RO! Read from l/I 11 d and output to DCE. Next, in the data link setting stage and data link cutting stage of the data transfer phase, transmission control is performed using control signals defined in the HDLC procedure, and data link setting and cutting are performed, respectively. In addition, in other stages of the data transfer phase, the transmission data formed by the unit 12 according to each protocol is subjected to frame processing of the HDLC procedure, and the response sent back from the partner station is monitored for each data transmission, and the HDLC signal is Performs sequence management, checks transmission errors, requests retransmission to unit 12, 0 insertion and O
Run Plusion. In the call disconnection phase, the interface circuit 11a is controlled to release the connection with the DCE.

In the data transfer phase, unit 12 forms each header and information following the header based on each protocol, and sequentially transfers this to unit 1. 1. When transferring image information, the data of the desired frame number is read out from the entire data memory 12f and transferred to the unit 11 in response to an instruction from the unit 11 (including a retransmission request).

At the time of reception, the received data is sequentially stored in the data memory 12f, the contents of each received header are decoded, all destinations of the corresponding data are determined, and the data is transferred.

For example, if the header of the received data is a session header, the data following this header is transferred to the SCU 5, and data processing according to each protocol is thus performed.

In FIG. 5, signal SABM is an asynchronous balanced mode setting command in the complex station, signal UA is a hail response indicating that the receiving side has accepted the command from the transmitting side, and signal U
I is a command for transferring information without changing the contents of the information section, and a signal DISCid is an operation mode termination command, and these signals SABM.

UA, UI and DISC are control signals for the HDI, C procedure. Signals TCA and TCR are signals for transport settings and are used for the transport header HD. Signal C8S is a session start command, signal R85
P is a session start positive response, signal C3UI is a session user information command, signal C8E is a session end command, and signal R8EP is a session end positive response, and these signals C8S, R85
P, C3UI, C8E and R8EP are used for session header HD2. The signal CDS is the document end command, the signal CDUI is the document user information command, the signal CDE is the document end command, and the signal RDEP is the document end affirmative command, and these signals CDS, CDUI.

CDE and RDEP are used for document header HD3.

First, the sending facsimile device (hereinafter referred to as the transmitting station) activates the unit 11 of CCU 1, connects to the DCE via the interface circuit 11a, requests the digital line network (hereinafter simply referred to as the network) to make a call, and makes the call from the network. When a yes signal is returned, dial information is sent to the network.

The network calls the other party's facsimile machine (hereinafter referred to as the receiving station) with the received dial information, and when the receiving station responds to this call, it notifies the transmitting station that transmission is possible. Call setup is done.

After the call setup is completed, the transmitting station transmits a signal SAnM to the receiving station, and when the receiving station returns a UA in response, a data link is established.

After that, the transmitting station sends the signal TCR to the receiving station to request connection of a communication path, and when the receiving station responds by sending back the signal TCA, transdestination is set. When the function etc. of the terminal is sent to the receiving station following the signal C8S, the receiving station sets the function of its own terminal that is compatible with that of the transmitting station, and transmits the set function to the transmitting station following the signal R85P. do. The transmitting station sets itself to the same functionality as the receiving station, thereby establishing a session (
session layer) settings are made.

Then, the transmitting station sets the document (document layer) (starts information transmission) using the signals C3UI and UI, and then sends the signals C3UI, CDUI and UI.
Image information is transferred using

When this image information transfer is completed, the transmitting station sends out the signal CDE, and in response, the receiving station returns the signal RDEP, which marks the end of the document (document layer), and then the sending station sends out the signal C8E, which When the receiving station returns the signal R8EP in response to this, the session (session layer) ends.

Thereafter, when the transmitting station outputs a signal DISC to the network to request a call termination, the network disconnects the call to the receiving station and confirms the call disconnection to the transmitting station, thereby terminating the facsimile transmission.

In this manner, facsimile transmission is performed.

In the above-described embodiment, the unit 11 also performs O-insertion and O-prevention, but if these processes are performed by another unit configured by a microprocessor, data processing can be made even faster. Can be done.

Although the above-described embodiment is a data transmission apparatus applied to a G4 facsimile, the present invention can also be implemented in a data transmission apparatus applied to a data processing apparatus other than a G4 facsimile.

〔effect〕

As explained above, in the present invention, the HDLC procedure including CRC processing for data checking, O insertion, and 0 delivery/processing that requires time is executed in one unit, and the HDLC procedure higher than this HDLC procedure is executed. Since the data control related to the protocol is executed by another unit, the data transmission device for devices with high data transmission speeds such as G4 facsimile machines can be implemented using a general-purpose 8-bit microprocessor. Transmission equipment can be provided at low cost. Furthermore, since the functions of the units are divided by protocol hierarchy, the software can be designed by dividing it for each protocol, thereby simplifying the software design.

[Brief explanation of the drawing]

FIG. 11 shows blocks 1 & I showing an embodiment of the present invention.
, Fig. 2 is a block diagram showing an example of a G4 facsimile machine, Fig. 3 is a conceptual diagram showing a layered protocol, and Figs. 4 (a) to (d) show the format of each transmission data. The conceptual diagram shown in Figure 5 is a flowchart showing an example of the transmission procedure. 1...CCU, 11.12...Unit, 11b. 12a...Microprocessor.

Claims (1)

[Claims] A first unit that establishes a transmission line and executes data framing processing, retransmission request control, and sequence control based on HDLC procedures, and a first unit that decodes the contents of transmission data when receiving and forms transmission data when transmitting. A data transmission device comprising: a second unit that transmits data to the first unit.