JPH0374946A - Error control system in data communication - Google Patents

Abstract

PURPOSE:To miniaturize an equipment and to select freely an error correction method by comparing an error detection code generated at a reception side and sent to a transmission side with an error detection code generated from an original data at the transmission side to discriminate the presence of an error. CONSTITUTION:A CPU 5 of a transmitter 1 sends a parallel data to the receiver 11 of a receiver 3 via a driver 7 and inputs the data to a parity checking circuit 9, which generates an error detection code. The receiver 3 latches the output of a receiver 11 at a latch 15, inputs the output to a parity generator 13, which generates an error detection code and sends the code to the parity checking circuit 9 at the transmission side. When the error detection signals generated by the transmission side and the reception side are coincident with each other, the CPU 5 sends a data strobe signal 17 and fetches the parallel data to the reception side. When they are discordant with each other, the CPU 5 selects the processing as to whether the data is retransmitted or the transmission is stopped. Thus, the equipment is miniaturized, the cost is reduced and the error correction means is selected flexibly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to an error control method in data communication that controls error detection in data transmitted from a transmitting device to a receiving device.

(Prior Art) When performing data communication, a receiving device or a transmitting device detects whether or not transmitted data contains an error.

Conventionally, as a control method for error detection, there has been a continuous transmission method in which a transmitting device repeatedly transmits the same data and a receiving device detects errors in this data.

There has also been a return verification method in which data received by a receiving device is returned as is to a transmitting device, and the transmitting device compares the returned data with the original data to detect errors.

Furthermore, the transmitting device uses a parity check code and a CR code.
There has been a code detection method in which an error detection code such as a C (cyclic redundancy check) code is added to data in advance and transmitted, and a receiving device detects errors based on this code.

If an error is detected by such error detection control, it has been determined that only a certain method out of several processing methods such as data retransmission or transmission cancellation is to be performed as subsequent processing.

(Problem to be Solved by the Invention) However, in such an error control method, a complicated error detection control circuit is required for both the transmitting and receiving devices.
Therefore, there was a problem in that the device became large and the price increased.

Furthermore, since only a certain method was used for processing after an error was detected, it was not possible to freely select a processing method as needed.

The present invention was made in view of the above-mentioned conventional circumstances, and its purpose is to reduce the size of the device using a simple control circuit and to provide flexibility in selecting a processing method after detecting an error. The object of the present invention is to provide an error control method in data communication that can be used to control errors.

[Structure of the Invention] (Means for Solving the Problems) In order to achieve the above object, the present invention provides an error detection code creation means for creating an error detection code based on transmission data from a transmitter, A receiving device is provided with a return means for returning the error detection code created by the creation means to the transmission device, a code creation means for creating an error detection code based on the original data of the transmission data, and a code creation means by the code creation means. g-matching means for comparing the generated error detection code and the error detection code returned by the return means to determine whether or not they are equal; The transmitting device is provided with an instruction means for instructing the device to take in the transmitted data.

(Operation) In the above configuration, in the present invention, the receiving device creates an error detection code based on transmission data from the transmitting device, and returns the created error detection code to the transmitting device. Then, in the transmitting device, the returned error detection code is compared with the error detection code created from the original data of the transmission data, and
Determine whether they are equal or not. Furthermore, if it is determined that they are equal, the transmitting device instructs the receiving device to capture the transmitted data.

(Example) Hereinafter, the present invention will be explained in detail using the drawings.

FIG. 1 is a block diagram showing the configuration of a transmitting/receiving device for explaining an embodiment of the present invention.

In the figure, a transmitting device 1 transmits parallel data such as character data and image (IT data) to a receiving device 3, and is composed of a CPU (central processing unit) 5, a driver 7, and a parity check circuit 9. .

Further, the receiving device 3 includes a receiver 11, a parity generator 13, and a latch circuit 15.

The CPU 5 controls the entire transmitting device 1,
For example, parallel data to be transmitted is passed to the driver 7, and the dry half is instructed to output this data.

Further, the CPU 5 also passes the same data as the parallel data passed to the driver 7 to the parity check circuit 9.

Further, the CPU 5 receives the determination result provided by the parity check circuit 9, and in accordance with the result outputs a data strobe signal 17, or performs processing such as retransmitting parallel data or canceling transmission.

The driver 7 outputs parallel data given by the CPU 5 to the receiving device 3.

The parity check circuit 9 generates an error detection code based on the parallel data given by the CPU 5, and compares this error detection code with the error detection code returned from the receiving device 3 to determine whether they are equal or not. It is something to do. The parity check circuit 9 then provides this determination result to the CPU 5.

The receiver 11 receives parallel data output from the driver 7 and outputs it to the latch circuit 15.

At the same time, the receiver 11 passes this data to the parity generator 13.

The parity generator 13 creates an error detection code based on the parallel data passed from the receiver 11. Further, the parity generator 13 returns the generated error detection code to the parity check circuit 9.

The latch circuit 15 latches parallel data output from the receiver 11. And latch circuit 1
5 outputs the latched parallel data to the data processing system in the receiver 3 when the data strobe signal 17 is output from the CPU 5.

One embodiment of the present invention is constructed in this manner, and will now be described in detail.

In order to transmit parallel data from the transmitting device 1 to the receiving device 3, the parallel data is first passed from the CPU 5 to the driver 7. At this time, this parallel data is also passed from the CPU 5 to the parity check circuit 9.

The parallel data passed to the driver 7 is outputted by the driver 7 to the receiver 11 in the receiving device 3.

Also, a parity check circuit 9 given parallel data
Then, an error detection code is created based on this data.

On the other hand, the parallel data output from the driver 7 is received by the receiver 11 and output to the latch circuit 15. At the same time, this parallel data is passed from the receiver 11 to the parity generator 13.

The parallel data output from the receiver 11 to the latch circuit 15 is latched by the latch circuit 15.

Also, the parity generator 13 to which parallel data is passed
Then, an error detection code is created based on this parallel data. Further, the generated error detection code is sent back from the parity generator 13 to the parity check circuit 9.

The error detection code sent back to the parity check circuit 9 is
It is compared with the error detection code created by the parity check circuit 9 to determine whether or not they are the same code. Then, the judgment result is sent to the CPU 5 from the parity check circuit 9.
given to.

At this time, if the determination result indicates that the codes are the same, the CPU 5 determines that there is no error in the parallel data received by the receiving device 3.

As a result, the data strobe signal 17 is sent from the CPU 5.
is output to the latch circuit 15. Then, latch circuit 1
The parallel data latched by the receiver 5 is output from the latch circuit 15 to the data processing system in the receiver 3.

However, if the determination result indicates that the codes are not the same, it is detected that there is an error in the parallel data received by the receiving device 3. As a result, the data strobe signal 17 is not output from the CPU 5. Therefore, parallel data will not be output from the latch circuit 15 either.

In this way, if an error is detected in parallel data,
As a subsequent processing method, the CPU 5 freely selects one of several processing methods according to necessity, such as retransmission of the same parallel data to the receiving device 3 or mid-transmission.

As described above, the receiving device 3 is configured only with a simple circuit that creates and returns an error detection code. Further, when an error is detected, the CPU 5 in the transmitting device 1 can flexibly select a subsequent processing method.

[Effects of the Invention] As explained above, according to the error control method according to the present invention, error control can be performed using a simple control circuit, so the device can be downsized and an increase in price can be prevented. .

Furthermore, it becomes possible for the transmitting device to freely select a processing method after error detection.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of a transmitting/receiving device for explaining an embodiment of the present invention. 1... Transmitting device 3... Receiving device 5... CPU (Central Processing Unit) 7... Driver 9... Parity check circuit 11... Receiver 13... Parity generator 15... Latch circuit 17...data strobe signal

Claims (1)

[Scope of Claims] An error detection code creation means for creating an error detection code based on transmission data from a transmission device; and a return means for returning the error detection code created by the error detection code creation means to the transmission device. a code creating means provided in the receiving device and creating an error detection code based on the original data of the transmission data; an error detection code created by the code creating means;
a collation determination means that collates the error detection code returned by the return means to determine whether or not they are equal; and if the collation and determination means determines that they are equal, the transmitting data is taken into the receiving device. 1. An error control system in data communication, characterized in that a transmitting device is provided with an instruction means for instructing.