JPS6264152A - Communication device - Google Patents

Abstract

PURPOSE:To obtain an XON/XOFF code transmitter/receiver sending a transmission/reception data correctly by using an XON/XOFF transmission request signal from an externally connected device so as to generate the XON/ XOFF code directly and sending the code to a communication line. CONSTITUTION:A communication control sub computer 12 has a function generating the XON/XOFF code in addition to the function controlling a communication LSI 10 and when a data is received from a terminal device 8, it is outputted to the communication LSI 10 by using the code. Then the data is outputted from the terminal device between the XON and XOFF codes, and fetched in a main computer 14. Further, the XOFF code to the terminal device 8 at the reception, that is, the XOFF code is sent similarly as the transmission interruption instruction. The operation is conducted by the XOFF transmission request generate by the main computer 14.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a communication device, and more particularly to an XON/XOFF code transmitting/receiving device that controls data transmission/reception using XON/XOFF codes.

[Traditional techniques]

Various types of communication between computers have been developed and are used in various fields. Conventionally, in personal computers,
XOFF/XO controls the start or end of transmission of transmission data, etc. by transmitting and receiving XOFF/XON.
N-code transmission/reception system % formula % Figure 4 is a conventional circuit configuration diagram of the XOFF/XON code transmission/reception system. Computer system 1 is a communication LS
I2. Communication control subcomputer 3. Receive buffer 4
．． Transmission buffer 5. It consists of a main computer 6. A terminal device 8 having a display device 9 and a communication LS 12 of the computer system 1 are connected to the communication line 7 . Note that each communication line 7 is connected at point A.

When some data is to be sent from the terminal device 8 to the computer system 1, first the XON is sent to the terminal device 8.
A code is applied via the communication LSI 2 and the communication line 7.

The XON code is a code for notifying the terminal device that the receiving device (computer system in this case) is in the receiving state. When the terminal device 8 receives this code, the terminal device recognizes that the receiving side device is in the receiving state as described above, and transmits data etc. to the computer system 1 via the communication line 7.

The terminal device 8 sends data to the computer system 1 until the XOFF code is sent from the computer system 1 to the terminal device 8 or until there is no more data to send. At this time, the data input from the communication line 7 by the communication LSI 2 is stored in the reception buffer, so the computer system 1 takes in the data stored in the reception buffer. Through this operation, data from the terminal device 8 is transmitted to the computer system 1. Note that if the computer system 1 is temporarily unable to take in the data stored in the transmission buffer 5 due to other processing, etc., the XOFF code is stored in the transmission buffer 5 and the data is read out by the communication LSI 2 and communicated. By transmitting the data to the terminal device 8 via the line 7, the data transmission from the terminal device 8 is stopped.

On the other hand, in contrast to the above, when a data sending request is sent from the terminal device 8 to the computer system 1 and the specified data etc. are sent from the computer system 1 to the terminal device 8 via the communication line 7.

The data to be transmitted is first stored in the transmission buffer 5 from the main computer 6. Note that the data stored in the transmission buffer 5 is, for example, in units of 1 byte or 1 word (2 bytes). The data stored in the transmission buffer 5 is read by the communication LsI 2 and sent one copy to the terminal device 8 via the f8 line 7.

As described above, in the conventional XOFF/XON code transmission/reception method, the computer system 1 is configured to apply the XOFF code from the terminal device 8 to the main computer 6 via the reception buffer 4. This X
With the addition of the OFF code, a stop command is output from the main computer 6 to the communication control subcomputer 3 (not shown), and 9 communication is stopped or terminated.

Therefore, even if the terminal device 8 issues a request to the computer system 1 to temporarily suspend transmission.

Since the XOFF code is applied to the main computer 6 via the reception buffer 4, a certain amount of time is required to stop sending the transmission data. For example, if the XOFF code is transmitted when the reception buffer 4 in the terminal device 8 is full, the terminal device 8 will not be able to receive the transmitted data at the aforementioned specific time, and the data will be lost.

Furthermore, even if the computer system 1 sends an XOFF code to stop sending data from the terminal device 8, reception proceeds while data is sent to the terminal via the sending buffer 5, resulting in the same problem as described above. A reception error may occur.

Furthermore, when the computer system 1 sends an XON code to a terminal device in order to resume reception, for example, there is a problem in that communication is delayed due to the transmission buffer 5 being passed through.

[Purpose of the invention]

In view of the above-mentioned drawbacks of the conventional technology, the present invention provides an XON in which control using an XOFF/XON code for starting, ending, or interrupting transmission/reception is performed correctly, and data to be sent or received is correctly transmitted.

The purpose of this invention is to provide an XOFF code transmitting/receiving device.

[Key points of the invention]

In order to achieve the above object, the present invention includes a transmitting means for transmitting data stored in a transmitting buffer to a communication line;
A communication device having a receiving means for storing data received from the communication line in a reception buffer, a first code generating means for generating an XON code in response to an XON sending request signal from an externally connected device and sending it to the communication line; XOF is triggered by an XOFF transmission request signal from an externally connected device.
A second code generating means for generating an F code and transmitting it to the communication line is provided.

And its effect is as follows.

XON transmission request signal or XOF from externally connected equipment
F transmission request signal causes the first. The second code generating means directly generates an XON code or an XOFF code, and transmits the XON code or XOFF code to the communication line without going through the transmission buffer. Further, whether the data added from the 0 communication line is an XOFF or XON code is directly determined by the determining means without going through the receiving buffer, and the transmitting means is operated according to the result.

〔Example〕

The present invention will be described in detail below using one drawing.

FIG. 1 is a circuit diagram of a first embodiment of the present invention. In FIG. 9, parts equivalent to the conventional circuit shown in FIG. 4 are given the same reference numerals and their explanation will be omitted.

Transmission data output from the terminal device 8 is applied to the communication LSI 10 via the communication line 7. The communication LSI 10 converts serial data input from the communication line 7 into parallel data and adds it to the reception buffer and the communication control subcomputer 12.

It also converts the data added from the transmission buffer 13 and communication subcomputer 12 into serial data and connects it to the communication line 7.
This is a circuit that outputs to. For example, serial data applied to the communication LS 110 is converted into parallel data by the communication LS I10 and output to the reception buffer 11 and the communication control subcomputer 12. The reception buffer 11 is a storage circuit that temporarily stores data added from the communication LSI to, and is output to the main computer 14. Thereby, the data output from the terminal device 8 is transmitted to the main computer 14.

Further, data outputted from the main computer 14 to the transmission buffer 13 is temporarily stored in the transmission buffer 13 and outputted to the communication LSI 10, where it is converted into, for example, serial data.

The signal is then outputted to the communication line 7 by the communication LSI 10 and added to the terminal device 8. Data is transmitted between the main computer 14 and the terminal device 8 through the basic operations described above.

On the other hand, in the embodiment of the present invention shown in FIG.
In addition to the communication control subcomputer 12 controlling l0, the communication control subcomputer 12 also controls the XON code,
It has a function of generating an OFF code, and when receiving data from the terminal device 8, outputs the code to the communication LSI 10.

As a result, data between the XON code and the XOFF code is outputted from the terminal device 8 and taken into the main computer 14. Also, XO to the terminal device 8 at the time of reception
Similarly, XOFF is used as an FF code, that is, a transmission interruption command.
Code is sent.

Note that this operation is performed by X generated from the main computer 14.
This is done by an OFF sending request.

Another communication control subcomputer operating as described above recognizes that when the data applied to the communication LSI 10 from the communication line 7 is converted and output as parallel data, the data is, for example, an x o l: F code. It has an XOFF code detection circuit 23-. For example, while data is being sent from the main computer 14, due to some condition (such as the receiving buffer of the terminal device being full), 'C' terminal device 8. When an XOFF code (transmission interruption) is sent.

The aforementioned XOFF code detection circuit 23 detects the code and outputs a stop command to the 2 communication LSI to stop sending out data to U7. This interruption instruction is also applied to the main computer, but since the communication control subcomputer directly controls the communication LS 10, for example, even if data is temporarily stored in the sending buffer 13, it is sent out. . Never. Since transmission is immediately stopped upon detection of this XOFF code, reception errors are prevented from occurring when the terminal device's buffer is full.

FIG. 2 is a detailed circuit diagram of a second embodiment of the present invention.

Subcomputer 1 of communication control subcomputer 12
When a request signal for sending an XOFF code or an XON code is added to the main computer 14 to the subcomputer 15, the subcomputer 15 determines the request to be sent and outputs the corresponding signal, that is, the X0NR signal or the XOFFR signal to the timing circuit 16. The X0NR signal or the XOFFR signal applied to the timing circuit 16 is asynchronous with the timing of transmission, for example, it is applied while another 1 byte of data is being sent, so the timing circuit 16 takes the transmission timing and converts the sending timing clock to the XOFF code generation circuit 17. Alternatively, it is output to the XON code generation circuit 18. The XOFF code generation circuit 17 or XON code generation circuit 18 to which this timing clock is applied generates a corresponding code, that is, an XOFF code or an XON code, and outputs it to the data selector 19. On the other hand,
OFF code generation circuit 17 and XON code generation circuit 18
The timing signal applied to is also applied to the OR circuit 20, and is configured to be output from the OR circuit 20 when either one of the generated timing clocks is output from the timing circuit 6. The output of the OR circuit 20 is sent to the transmission buffer 2 via the data selector 19 and the OR circuit 25.
1, and when the XOFF code or XON code is sent, the data stored in the transmission buffer 21 is not output to the data selector 19, and the data selector 19
Alternatively, the output of the XON code F generation circuit 18 is selected and switched to be added to the communication LSI10. Then, for communication, the S I 10 outputs the added code, ie, the XOFF code or the XON code, to the communication line 10 that does not require it. 9. In normal transmission, the transmission buffer 21 is configured to output stored data to the data selector by a signal applied from the Sl control circuit 24 via the OR circuit 25.

On the other hand, data applied to the communication 1,5110 from a communication line (not shown) is converted into bit parallel data by the communication LSI 10 and output, and is applied to the main computer 14 via the reception sofa 22. It is also added to the XOFF code detection circuit 23. The XOFF code detection circuit 23 constantly detects whether data applied from the communication LSI is an XOFF code, and outputs a detection signal to the LSI control circuit 24 when detected. The LSI control circuit 24 is.

When the detection signal is added, a transmission stop signal is output to the 1 communication LSI 10, and transmission of the data stored in the transmission buffer 21 is stopped.

FIG. 3 is a timing chart for transmitting the XON/XOFF code according to the embodiment of the present invention. The two communication lines are full duplex, and the timing chart shows a case where transmission and reception can be performed at the same time. Data A and B in the transmission buffer 21
, C, and D are added.

The data is temporarily stored and sequentially outputted from the transmission buffer in synchronization with the transmission timing. At this time, the input to the data selector 19 is at L level.

The data selector 9 selects the output of the transmission buffer 21 and outputs it to the communication LSI 10. Therefore.

A data signal applied to the main computer 14 is output to the communication circuit. As mentioned above, the communication line is full duplex, so at the same time the data signal Z
, Y, X, W... are added to make platform 3 communication t, 5ri
The data are sequentially stored in the reception buffer 22 via the In this state, if a processing ITJ request is sent to the main computer 14 from another device, and if reception processing becomes impossible, the main computer 14 sends an XOFF code to the subcomputer 15 of the communications subcomputer 12. A transmission request signal is added.

This XOFF sending request signal causes the subcomputer 1 to
5 is the XOFF transmission signal XOFR to the timing circuit 1G.
■ Output. In response to the XOFF sending signal, the timing circuit 16 outputs a signal synchronized with the sending timing clock. This signal applies an H level to the data selector 19 via the OR circuit 16, so the data selector 19
selects the signal applied from the XoFF generation circuit 17 and outputs it to 3110 for communication. By this selection, the XOF'F code output from the XOFF code generation circuit 17 is inserted between the transmission data D and the transmission data E and is transmitted.

For example, the terminal device receiving this data is
Transmission is stopped when the F code is received. This XOF
Since the data of the F code is sent out without passing through the transmission buffer, for example, even if data E and F are stored in the transmission buffer 21, they are sent out before that data. still,
A terminal device also has the circuit according to the embodiment of the present invention shown in FIG. 2, and the terminal device stops transmitting immediately upon receiving the XOFF code. In FIG. 3, the terminal device is transmitting data V while the XOFF code is being transmitted, but as the effect of the present invention is to directly detect the XOFF code, transmission of data V and subsequent data is immediately stopped.

For example, other processing by the main computer 14 ends.

When reception processing becomes possible, the main computer 14
sends a request to the communication subcomputer 12 to send an XON code, and the XON code is immediately sent in the same manner as the XOFF code described above. As a result, subsequent data U, T, . . . are sent from the terminal device. On the other hand, when the terminal device becomes unable to receive data due to processing on the terminal device side, the terminal device sends an XOFF code. Therefore, as described above, the XOFF code detection circuit detects this code and stops sending the data after data L that was being sent when the code was being received. still.

The transmission data buffer 21 stores the data to be transmitted (for example, 2 bytes), but since the LSI control circuit 24 outputs a transmission stop signal to the communication LSI 10, it is not output to the 8th line. Furthermore, since the transmission stop signal is also applied to the transmission buffer 21 via the OR circuit 25, it is not output from the transmission buffer 21, and no data is lost when transmission is stopped (interrupted).

and.

The stop is performed by receiving the XON code sent later from the terminal device, detecting it in the main computer 14, and sending the transmission restart signal from the main computer 14 to the LSI control circuit 2a via the communication subcomputer 12 at H level O. restarted by joining.

Although the present invention has been described above, the present invention is not limited to data transmission between a main converter and a terminal device.

For example, the present invention can be applied to a data transmission link between a computer and another computer, or to a device that transmits data by controlling it using XON and XOFF codes.

Furthermore, it is also possible to provide two of the present inventions in opposing devices. moreover.

In the embodiment of the present invention, transmission is immediately stopped when an XOFF code is received, but this is not limited to the XOFF code.For example, by adding an XON code detection circuit, It is also possible to speed up the data transmission response at the time of reception.

〔Effect of the invention〕

As described above, the present invention is generated by two main computers, etc., and transmits the XON code or XOFF code requested by the main computer before the data stored in the transmission buffer, so the time required for transmission is short. The occurrence of errors in reception can be prevented, and since transmission is immediately stopped when an XOFF code added from two lines is received, the occurrence of reception errors on the receiving device side can be prevented. An XON that is correctly controlled by the XOFF/XON code for interruption and that transmits sending or receiving data correctly.

You can also remove the XOFF code transmitter/receiver.

[Brief explanation of drawings]

FIG. 1 is a circuit configuration diagram of a first embodiment of the present invention. FIG. 2 is a detailed circuit configuration diagram of a second embodiment of the present invention. FIG. 3 is a timing chart 1 for transmitting an XON/XOFF code according to an embodiment of the present invention. FIG. 4 is a circuit diagram of a conventional XOFF/XON transmission/reception system. 2.10... LSI for communication. 3.12... Communication control subcomputer. 4.22...Receiving pants 1゜5.21...Sending buffer. 16...timing circuit. 17...XOFF code generation circuit. 1st...XON code generation circuit. 23...XOFF code detection circuit. 24...LSI control circuit. Patent Applicant: Casio Computer Co., Ltd. Soushin Kyoui J/1st Scale Diagram of Invention 4+ Figure 1 Main Light θFl 72 Echi PJh Detailed 7th Scale Diagram Figure 2

Claims (9)

[Claims] (1) Transmitting means (13, 10) for transmitting data stored in a transmitting buffer to a communication line, and receiving means (1) for storing data added from the communication line in a receiving buffer.
1, 10), a first code generating means (12) for generating an XON code in response to an XON transmission request signal from an externally connected device and transmitting it to the communication line;
, 18) and second code generation means (12, 17) for generating an XOFF code in response to an XOFF transmission request signal from an externally connected device and transmitting it to the communication line. Code transmitting and receiving device. (2) The receiving means has a discriminating means for discriminating whether the data applied from the communication line is at least one of an XOFF code or an XON code, and the transmitting means operates according to the discriminating result of the discriminating means. XON, X according to claim 1, characterized in that
OFF code transmitting/receiving device. (3) The XON, XOFF code according to claim 2, wherein the transmitting means stops transmitting the data stored in the transmitting buffer when the XOFF code is detected by the determining means. Transmitting/receiving device. (4) The transmitting means has a switching means, and the first and second
When the code generating means generates the XON code and the XON described in range 1,
XOFF code transmitting/receiving device. (5) The transmission means has a timing generation means, and when a transmission request for at least one of an XON code and an XOFF code is applied from an externally connected device, the timing generation means switches the switching in synchronization with the timing signal of the transmission data. The XON/XOFF code transmitting/receiving device according to claim 4, characterized in that the means is switched. (6) The timing generating means has an OR gate, and
The XON and XOFF code transmitting/receiving device according to claim 5, wherein an ON code transmission timing signal and an XOFF code transmission timing signal are applied to the OR gate, and an output of the OR gate is applied to the switching means. . (7) The XON and XOFF according to claim 1, wherein the externally connected device is a computer.
Code transmitting and receiving device. (8) The XO according to claim 1, wherein the communication line performs serial bit data transmission.
N, XOFF code transmitting/receiving device. (9) In a communication device having a transmitting means for transmitting data stored in a transmitting buffer to a communication line, and a receiving means for storing data added from the communication line in a receiving buffer, the transmitting means is provided between the receiving buffer and the communication line. XON, XOFF code transmission and reception, characterized in that it has a determining means for determining whether or not an XOFF is applied from a communication line, and a control means for stopping the transmission of the transmitting means when the determining means determines the XOFF code. Device.