JPS5869147A - Data transmission system - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency, by outputting an error detection code through inversion together with a transmission end signal for already transmitted data when the data transmission is stopped on the way, detecting the code at the reception side, and immediately discriminating the abnormity of the transmission side. CONSTITUTION:A data from a line 10 is received at a data processing circuit 1 and the data is applied to a terminal device 11 via a selection circuit 4 and an interface 6. In this case, the transmitted data DATA, a transmission end code ED and a format (a) with an error detection code CHK are applied to an EOR gate 3. Further, the ED and CHK are applied to an end code generating circuit 5 and an error code generating circuit 2. When the necessity for stopping data transmission at the circuit 1 takes place, the transmission stop signal is applied to the circuits 2, 4 and 5, the code CHK is inverted at the gate 3 to be inversion CHK', and a part of the data DATA, the end code ED and the inversion CHK' are transferred to the device 11. The code ED and the inversion CHK are detected at an error detection circuit 8 and an end code detection circuit 9 and applied to the circuit 1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission system that interconnects data transmission apparatuses and uses an error detection code that can detect code errors V in transmitted data. As shown in Figure 1 (a) or (b), data 1) AT
After A, the end code ED indicating the end of this data and the error detection code CHK of the data DATA are sent, and if the end code ED is not detected on the receiving side even after a time equivalent to the maximum data length has elapsed, a reception error (reception timeout) is detected. Judge and enter.

However, in such a transmission method, an abnormality in the transmitted information during data transmission is detected by the presence or absence of an end code after a time equivalent to the maximum data length has elapsed, so the transmitting side will have to wait until the next data transmission to complete the transmission of the maximum data length. This method has the drawback that it requires a long wait and data transmission efficiency is poor.

SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission system that eliminates the above-mentioned drawbacks.

Figure 2 (al and (blti) shows a data format for explaining one embodiment of the present invention.
When transmitting data using the data format shown in +,
Assuming that an abnormality occurs during the transmission of the data IJATA, the transmission method of the present invention will stop the transmission of the data DATA at the moment the abnormality occurs, and will The code ED indicating the end of the error detection code and the inverted code (inverted error detection code) CHK are continuously transmitted after the data is stopped, and the receiving side detects the codes ED and CHK from the transmitting side. An abnormality in the data is detected. Therefore, an abnormality in the transmitted data can be detected without having to wait for a time corresponding to the maximum data length as in the conventional method, thereby improving data transmission efficiency.

FIG. 3 is a block diagram of a data transmission device used in the transmission method of the present invention. In the figure, a data processing circuit 1 made up of a microcombination unit receives data sent from a data processing circuit (not shown) via a line 1O. This data is given to the terminal device 11 via the selection circuit 4 and the interface 7/8 6. The output of the selection circuit 4 is an error detection code (parity check bit) circuit 2.
is given to generate an error detection code that is appropriate for the data. The processing circuit 1 sends the data through the selection circuit 4'1 and provides an end signal to the end code generation circuit 5 and the error code generation circuit 2. These code generators I#S5 and 2
is given in response to the detection signal from the processing circuit 1. Note that the switching signal for the selection circuit is given from the processing circuit 1.

In such a configuration, in the processing circuit 1, as soon as it becomes necessary to stop data transmission, a transmission stop signal is given to the circuits 2.4 and 5, and the signal a is sent to the circuits 2.4 and 5.
Invert (invert) the L4J) detection code CHK that is output as 1 through the exclusive OR (EOR) gate 3.
(C)IK) After the aborted transmission data, the processing circuit 1 passes the termination code ED and the inverted error code S circuit 7.
The signal from the circuit 7 is input to the end code detection circuit 9, and the end code ED is detected. As shown in 0 or more, which is immediately notified to circuit 1 when the ED code is detected in circuit 9, in the present invention, if it is desired to stop data transmission before the data transmission is completed, transmission is terminated following the already transmitted data. The notification code ED is output, and the error detection code is inverted and outputted, and on the receiving side, by detecting the reception of this inverted error 9 detection code, it is possible to know the abnormality on the sending side immediately, improving transmission efficiency. 0

[Brief explanation of the drawing]

Figures 1 (al and b) are diagrams showing data formats for explaining conventional data transmission methods, and Figure 2 (a
) and (bla) Figure 3 explaining the transmission method of the present invention.
The figure is a block diagram of a device used in the transmission system of the present invention. In FIG. 3, 1... data processing circuit, 2...
...Error detection code generation circuit, 3...EO
R gate, 4... Selection circuit, 5... End code generation circuit, 6.7... Interface, 8... Error detection circuit, 9... ... Termination code detection circuit 0 Fig. 1 (ii) (b)

Claims (1)

[Claims] In a data transmission system, when the transmission of predetermined data is stopped midway, a code in which at least one bit of an error detection code corresponding to the data is inverted and the end of the data is notified after the already transmitted data. A data transmission method characterized by transmitting a code.