JPH01302932A - Data transmission equipment - Google Patents

Abstract

PURPOSE:To securely transmit data in accordance with a transmission state by continuously generating start codes when the transmission state is bad and transmitting data with the continuous start codes. CONSTITUTION:A transmission device generates an information message consisting of the start codes STX201a and 201b, a text 203, a text termination code ETX205 and a block check character BCC207, and transmits it. When a reception device cannot receive the information message, it returns a negative acknowledge. When the reception device receives the negative acknowledge, it counts the number of receiving times in a counting means 2, and transmits the message again. When the number of receiving times reaches a prescribed set point, a control means 6 is operated through a discrimination means 4, and the start codes are continuously generated, whereby data is transmitted with STX201a and 201b. Thus, data can securely be transmitted in accordance with the transmission state.

Description

DETAILED DESCRIPTION OF THE INVENTION OBJECTS OF THE INVENTION (Field of Industrial Application) The present invention relates to a data transmission device that reliably transmits data according to transmission conditions.

(Prior Art) As a conventional data transmission method for transmitting serial data between a host computer and a terminal device, for example, J
Those specified in IS-06326 are known.

In such a conventional data transmission system, as shown in FIG. 7, a start code (STX) 201 and data (text) 2 are
03, an end-of-text code (ETX) 205, and a block check character (BCC) 207 to form an information message, which is transmitted for each information message.

A conventional data transmission system will be explained with reference to FIG.

When the host computer performs polling to prompt a specific terminal device to send a message at time t1, the corresponding terminal device transmits the above-mentioned information message at time t2.

For example, if the host computer is unable to receive an information message from the terminal device due to poor transmission conditions,
Negative response (NA) indicating that it could not be received at time t3
K) is returned to the terminal device.

When the terminal device side receives a negative response from the host computer, it transmits the information message again at time t4. This ensures reliability of data transmission.

(Problems to be Solved by the Invention) However, if the transmission conditions between the host computer and the terminal device are poor, the host computer will return a negative response every time an information message is sent from the terminal device.

For example, if the host computer cannot receive the information message sent from the terminal device at time 1++ in FIG. 8, it returns a negative response to the terminal device again at time t12. When the host computer returns a negative response indicating that the information message could not be received due to poor transmission conditions a predetermined number of times, the terminal device transmits an end of transmission code (EOT) at time t+3 and remains in an abnormal state, i.e. The host computer ends data transmission even though it cannot receive the information message.

The present invention has been made in view of the above, and an object of the present invention is to provide a data transmission device that can reliably transmit data depending on the transmission state.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention, as shown in FIG. In the data transmission device, the transmitting device transmits the information message again when there is a negative response indicating that the message could not be received; a discriminating means 4 for outputting a discriminating signal when the count value by the counting means 2 reaches a predetermined value; and a discriminating means 4 for continuously generating the start code in response to the discriminating signal from the discriminating means and transmitting the data. It is characterized by comprising a control means 6 for transmitting the plurality of consecutive start codes prior to the start codes.

(Operation) According to the present invention, when a transmitting device transmits an information message consisting of a start code and data, the receiving device returns a negative response if the information message cannot be received. When the sending device receives a negative response from the receiving device, it sends the information message again. Thereafter, the transmitting device similarly transmits the message again every time it receives a negative response from the receiving device. At this time, in the transmitting device, the counting means 2 counts the number of times negative responses have been received, and when the count of the counting means reaches a predetermined value, the determining means 4 outputs a determining signal. The transmitter is also provided with a control means 6 that continuously generates a start code based on the discrimination signal and transmits data after the start code.

Therefore, under normal transmission conditions, an information message consisting of one start code and data is transmitted, and when the transmission condition deteriorates, an information message consisting of a plurality of successive start codes and data is transmitted. This allows data to be transmitted reliably.

(Example) Hereinafter, an example according to the present invention will be described in detail with reference to the drawings.

First, the configuration of an image information storage and retrieval device to which the present invention is applied and its peripheral devices will be explained with reference to FIG.

The image scanner device 1 is a device for reading the content written on a document such as a photograph or a document as image information from a reading section configured by an image sensor such as a COD. The image scanner device 1 includes an operation section 3 for setting parameters such as the document size, document density, and reading density of the document to be read, a memory (not shown) for storing these set parameters, and the like. A CPU (not shown) that controls the entire image scanner device 1, a display section 5 that displays input information such as setting conditions and processing time, and a CPU (not shown) that continuously reads a document placed on a document table (not shown). The automatic paper feed mechanism (ADF) transports documents to the
)7.

A control unit (CPU) 11 controls the overall operation and data flow of the information processing device.

That is, the control unit 11, the DMA 13 (to be described later), the main memory 51, the buffer memory 53a, and the page memory 53b.
1 code/image converter 71, display memory 73, IP
The U90, CODEC95, etc. are connected via the system bus 20.

Similarly, the control section 11 is connected to a buffer memory 53a, a page memory 53b1, a code/image conversion section 71, a display memory 73, an IPU 90, a CODEC 95, and the like via an image bus 40 for transmitting image information.

Furthermore, the control unit 11 executes control regarding the transmission of serial data between the image information storage and retrieval device and the printer 9 connected to the image information storage and retrieval device.

Further, an external data input device 100 is connected to this control section 11 via an interface circuit 11a.

The data input device 100 can be used, for example, to move the cursor displayed on the screen of the display device 77 when inputting character information when creating a document using a word processing function, or when performing a search or image processing. A keyboard 101 and a mouse 1 for inputting search information, various command information, arrangement formats, etc. for switching various functions.
03 are provided.

DMA (D 1rect Memory Accesses
s) 13 transfers data regardless of the operation of the control unit 11, and for example, transfers data between the buffer memory 53a and the storage device 30 via the interface 13a.

The storage device 30 includes a magnetic disk device 31 that stores information for specifying desired image information from a large amount of image information, that is, search information, etc., and a magnetic disk device 31 that stores information for specifying desired image information from among a large amount of image information, and a magnetic disk device 31 that stores information for specifying desired image information from among a large amount of image information, and a magnetic disk device 31 that stores information for specifying desired image information from among a large amount of image information. It is composed of an optical disk device 33 and the like that stores search information and the like.

The main memory 51 stores operating programs for the control section 11 described above, such as control programs related to data transmission between the image information storage and retrieval device and the printer.

The buffer memory 53a has a storage capacity of, for example, 128 bytes, and sequentially stores code data whose redundancy has been compressed by the CODEC95.

Further, the buffer memory 53a is provided with a counter for counting the amount of stored data, and when the amount of stored data based on the count value of this counter reaches, for example, more than half of the storage capacity, that is, when the amount of stored data reaches 64. When more than a byte of code data is stored, the 64-byte data is sent word by word to the optical disk device 33 via the system bus 20 and the interface circuit 13a.

For example, the page memory 53b stores a number of pages for an A4 size document.
It has a storage capacity that can accommodate 0 pages, and temporarily stores image information input from the image scanner device 1 or image information retrieved from the optical disk device 33. Further, this page memory 53b stores simulated data for executing a self-diagnosis by simulation according to the present invention when the power is turned on.

For example, the code/image converter 71 converts the keyboard 10
It converts the character code data input from 1 into image data and outputs it to the display memory 73, and if necessary, by performing reverse conversion, the characters converted into image data on the screen are corrected, etc. .

The display memory 73 is a memory that temporarily stores image information when the display device 77 displays an image based on the image information from the page memory 53b or the like.

The display control unit 75 controls the drive of a display device 77 such as a CRT, and controls the display of image information stored in the display memory 73.

The CODEC 95 is an encoding/decoding circuit unit, and can reduce the storage area of a storage medium such as an optical disk used during registration by compressing image information, that is, by reducing redundancy.

Further, the GODEC 95 is a circuit unit that performs decompression processing of the compressed image information, that is, restores the reduced redundancy to the original image information and outputs it as the original image information.

This C0DEC95 has an IPU (Imaoe Pr
ocessir+gU ntt ) 90 is connected.

This IPU 90 includes an enlargement/reduction section 91 that enlarges and reduces image information, and an aspect/horizontal conversion section 9 that rotates image information.
It has a built-in 3.

Furthermore, output devices such as the image scanner device 1 and the printer 9 are connected to the interface circuit 95a.

The printer 9 is a device that prints out image information as visible information such as characters on a recording medium such as paper, and is, for example, a laser printer.

Further, the printer 9 is a transmitting device that transmits information for each message consisting of a start code and data based on polling from the image information storage and search device, and the image information storage and search device receives information for each message from the printer 9. It is a receiving device.

Further, to explain the internal configuration of the printer 9 in detail, it includes a transmitting circuit that transmits the above-mentioned message information, a counting circuit that counts the number of negative responses received from the image information storage and retrieval device, and a count value of this counting circuit. The control circuit includes a state discriminating circuit that discriminates the transmission state based on the transmission state, and a control circuit that continuously generates a start code based on the discriminating signal of the state discriminating circuit and controls each of these circuit units. When the state determining circuit determines that the transmission state is defective, data is transmitted after the plurality of consecutive start codes based on a control command from the control circuit.

Next, an explanation will be given of the operating procedure using, as an example, a case in which the image information storage and retrieval device shown in FIG. 2 reads a large number of originals, registers the image information written on the originals, and performs a search and printout.

First, when registering the read image information, follow the instructions on the initial information processing screen displayed on the display screen of the display device 77 to read the document and transfer the read image information to the predetermined optical disk device 33. [Enter commands etc. from the keyboard 101 for continuous registration]
Then, the image information storage and retrieval device is set to the ``1 reading registration'' mode.

Next, a number of other originals are stacked and placed on a predetermined position such as the original table of the image scanner device 1 constituting this image information storage and retrieval device, and the stacked originals are further read continuously. After setting the automatic document feeding (ADF) J mode, information regarding initial settings such as the document size, document density, and reading density of this document is input from the keyboard 101 or the operation unit 3 of the image scanner device 1.

Further, after the image information from the image scanner device 1 is temporarily stored in the page memory 53b, the buffer memory 53
The information is transmitted to the optical disc device 33 via the interface circuit 13a and the interface circuit 13a, so that it can be registered on an optical disc (not shown) that is a storage medium of the optical disc device 33.

Next, use the keyboard 101 to register the title of the manuscript,
Display device 7 displays search information such as information amount and arrangement format.
Enter according to the format displayed on the screen in step 7.

=12- This format is used to input and set search key items to specify the document to be registered and to facilitate the search process, and is used to input and set search key items to facilitate the search process. 30's remaining capacity, etc., a "table" for inputting key items for the above search, and a keyboard 101.
When inputting using the function keys configured in
The function of this function key is displayed.

When reading the document starts, the image information read from the image scanner device 1 is sent to the interface circuit 95a.
-H page memory 53b via -H page memory 53b. Subsequently, after the image information is compressed by the C0DEC 95, the buffer memory 53a and the interface circuit 13a
Search information is registered in the magnetic disk device 31 via the search information, and search information and image information are registered in the optical disk device 33.

When searching for specific image information from among a large amount of image information registered in the optical disk device 33 and printing out the searched image information, use the keyboard 101 in the same way as in the case of [read registration] described above. Enter the search command using the ``Search'' mode.

Next, use the keyboard 101 to input search information for specifying desired image information, select the desired search information from a large number of search information recorded in the magnetic disk device 31, and apply the search information to the selected search information. Based on optical disk device 33
Search for the desired image information registered in . The image information retrieved in this way is sent from the optical disk device 33.
It is applied to the CODEC 95 via the interface circuit 13a and buffer memory 53a.

The CODEC 95 restores the retrieved image information by processing such as expansion, and displays it on the display device 77 via the display memory 73 or the like.

When making a so-called hard copy of the displayed image information, the user uses the keyboard 101 to designate the image information desired to be made into a hard copy, sets the number of copies to be output, etc., and prints out the image from the printer 9.

Next, the operation of the embodiment according to the present invention will be explained with reference to FIGS. 3, 4, and 5.

As shown in FIG. 3, when the image information storage and retrieval device specifies the address of the printer 9 and performs polling at time t21, the printer 9 receives the start code STX, data (text), and text end code ETX at time t22. and a block check character BCC. Step 22 shown in FIG.
In step 1, the created information message, that is, a message containing one start code and data is transmitted.

If the image information storage and retrieval device cannot receive the message from the printer 9 due to poor transmission conditions, the time t23
A negative response NAK is returned to the effect that it could not be received.

In the printer 9, a negative response NAK is sent in step 223.
If a negative response NAK is received, the process proceeds to step 225 and counts the number of negative response receiving circuits. Further, when the printer 9 receives a negative response NAK, it transmits the above-mentioned message again at time t24 in FIG. 3-15=. Similarly, the printer 9 retransmits the above-mentioned message every time it receives a negative response NAK from the image information storage and retrieval device.

In step 227 shown in FIG. 4, it is determined whether the counted value of the number of negative responses received has reached a predetermined set value N1, and when the counted value reaches the set value N1, the process advances to step 229 and control is performed. operate the means. Next, in step 231, as shown in FIG. An information message consisting of is created, and this created information message is transmitted at time t33 shown in FIG. When the image information storage and retrieval device receives the information message containing these two consecutive start codes, the printer 9 sends an acknowledgment ACK1 indicating that the information message has been received at time t34.
Send it back to

As a result, the printer 9 transmits the transmission end code EOT at time [35] and ends the data transmission.

In this way, when two successive start codes are transmitted from the printer 9 prior to data transmission, the image information storage and retrieval device on the receiving side receives data in response to the two consecutive start codes. Timing adjustments will be made to do so. Furthermore, the reliability of data transmission can be further improved by configuring the structure so that the consecutive start codes are not limited to two, but are transmitted three or more times depending on the transmission status. can.

In the above-mentioned embodiment, a case was explained in which a message is sent from the printer and the message is received by the image information storage and retrieval device, but in the reverse case, in other words, the message is sent from the image information storage and retrieval device and the message is received by the printer. It can also be applied when receiving data.

Furthermore, in the embodiments described above, data transmission between the image information storage and retrieval device and the printer was explained as an example.
The present invention is not limited thereto and can be applied to any appropriate data transmission device.

For example, as shown in FIG.
The present invention can be applied to serial data transmission between 1 and printer 243.

As mentioned above, in normal times, the start code is transmitted only once before the data, and when the transmission condition deteriorates, the start code is transmitted twice consecutively before the data, so that the transmission condition does not change. Appropriate data transmission can be performed accordingly, and data can be transmitted quickly, especially in normal times.

[Effects of the Invention] As explained above, according to the present invention, start codes are generated consecutively when the transmission condition is poor, and data is transmitted together with a plurality of consecutive start codes. , data can be reliably transmitted depending on the transmission status. Furthermore, the occurrence of transmission errors can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a complaint correspondence diagram, and FIG. 2 is a block diagram showing an image information storage and retrieval device and a printer to which the present invention is applied.
FIG. 3 is an explanatory diagram showing data transmission between the image information storage device and the printer over time, and FIG. 4 is a flowchart showing the control flow for the printer.
FIG. 5 is an explanatory diagram showing an information message, FIG. 6 is a block diagram showing another embodiment of the present invention, and FIGS. 7 and 8 are explanatory diagrams showing a conventional example. 1... Counting means 3... State determining means 5...
control means

Claims (1)

[Scope of Claims] After a transmitting device transmits an information message consisting of a start code and data, if a negative response is received from a receiving device indicating that the information message could not be received, the transmitting device transmits the information message again. In the data transmission device, the transmitting device includes a counting means for counting the number of times the negative response is received, a determining means for outputting a determination signal when the counted value by the counting means reaches a predetermined value, and the determining means. 1. A data transmission device comprising: control means for successively generating the start codes in response to a discrimination signal from a plurality of start codes, and transmitting the plurality of consecutive start codes before transmitting the data.