JPH05145526A - Data communication equipment - Google Patents

Abstract

PURPOSE:To prevent an output of error data by allowing an output circuit to output same output data twice separately, allowing a receiver side to compare both data and discriminating the data to be data subjected to noise effect during transmission when they are not identical and invalidating the discriminated data. CONSTITUTION:An output circuit 2 sends same data of measurement circuits 11-13 to a receiver side I/F circuit 4 via a transmission line 3 as 1st and 2nd data separately twice. A holding circuit 51 of a discrimination circuit 5 latches the 1st data and when the 2nd data are outputted, a comparator circuit 52 compares the 1st data and the 2nd data stored in the circuit 51 to discriminate whether or not they are identical. When the result of discrimination indicates to be identical the circuit 5 allows the latch circuit 53 to output the 2nd data to a processing circuit 6. If not, the circuit 5 invalidates the 1st and 2nd data while regarding it that the effect of noise takes place and inhibits the output to the circuit 6. Thus, the output of erroneous data is prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication apparatus which determines whether data transmitted by a transmission line is correct or not and does not output this data to a circuit in the subsequent stage when an error occurs in the data.

[0002]

2. Description of the Related Art In ordinary data communication, the state of each object to be measured is converted into an electric signal, which is output to a receiving circuit via a serial or parallel transmission line, In general, this receiving circuit performs a predetermined process and then transmits it to a processing circuit corresponding to each of the measured objects. By the way, the predetermined processing is to check whether or not the data is accurately output to the receiving circuit. For example, even if an error occurs in the data due to noise that occurs during transmission, this data is checked using a means such as a parity check. Is not output to the circuit in the subsequent stage.

However, in the parity check, when an error occurs in 2-bit data in one transmission, this data may be treated as accurate data, which causes erroneous data.

[0004]

In order to solve the above-mentioned problems, the present invention outputs the output data of the output circuit in two steps corresponding to the quantity to be measured, and receives this data internally. In the determination circuit having the comparison circuit, the both output data are compared, and if the two are the same, this data is validated and output as it is to the circuit in the subsequent stage. This data is invalidated.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention is shown in FIG. 1 and explained. Measuring circuits 11, 12 and 13 are provided for each measured object,
The electric signal according to the change of each state is output to the output circuit 2. The output circuit 2 is an interface circuit for converting the data of the measuring circuits 11, 12, 13 into data for serial communication. The data converted to serial is the transmission line 3
Is output to the interface circuit 4 on the receiving side via
The interface circuit 4 converts the data into parallel data. After the parallel data is checked for correctness by the judgment circuit 5, if it is judged that there is no error in the data, the parallel data is output to the processing circuit 6 in the subsequent stage and each processing is performed.

Next, the operation of the output circuit 2 and the judgment circuit 5 which are the main parts of the present invention will be further described. The output circuit 2 outputs the same data to the interface circuit 4 twice, that is, dividing into the first and second data. The first data is first stored and held in the holding circuit 51. Next, when the second data is output, the comparison circuit 52 compares the second data with the first data stored in the holding circuit 51,
If they are the same, a signal is output to the latch circuit 53, and the second data output from the interface circuit 4 is processed.
Output to. However, when it is determined that the comparison result in the comparison circuit 52 is not the same, it is considered that there was an influence of noise during the transmission of the first or second data, this data is invalidated, and the data is sent to the processing circuit 6. Is prohibited from being output.

That is, it is possible to easily determine whether or not the data has been transmitted accurately by outputting one data dividedly twice and comparing them.

Although the specific circuit of the decision circuit 5 is not described in the above embodiment, the first data is already input to one input of a plurality (the same number as the number of bits of data) of the EX-OR gates. The second data is input to one input, the output of each EX-OR gate is connected to the OR gate to form a comparison circuit, and the output of the OR gate is set to the latch circuit 53.
It may be configured to be output to, and the point is that the first and second
If the data is not the same, the circuit configuration may be such that the data is not output to the processing circuit 6.

Further, in this embodiment, if there is an error in even one portion of the data to be transmitted, the entire data is invalidated. However, the determination circuit 5 is provided for each object to be measured, and only the data including the erroneous bit is provided. A circuit configuration for invalidating is also possible.

[0010]

As described above, according to the present invention, the output data generated according to the quantity to be measured is output twice via the transmission path, and the data output twice is transmitted by comparison. It is possible to determine whether or not there is an influence of noise, and there is an effect that erroneous data is not output to the circuit in the subsequent stage.

[Brief description of drawings]

FIG. 1 is a block diagram showing a preferred embodiment of the present invention.

[Explanation of symbols]

 2 Output circuit 3 Transmission line 5 Judgment circuit 52 Comparison circuit

Claims (1)

[Claims] 1. An output circuit for transmitting output data generated according to a measured quantity to a transmission path twice, and a comparison circuit for comparing output data which are continuously output. And a determination circuit that invalidates all or part of the output data when the two are not the same.