JPS5819180B2 - How to detect errors in signal transmission - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data transmission control and data transmission inspection method for exchanging data between program control devices.

For the sake of simplicity, a case will be described below in which data is transmitted from one to the other between two program control devices.

Conventionally, this type of system has been shown in FIG. 1, FIG. 2, or FIG. 3.

In Figure 1, 1 and 2 are program control devices, 3 is an address signal line in which a parity bit is added to the address signal indicating the type of data, and 4 is a parity bit added to the data signal indicating the content of the data corresponding to 3. This figure shows the data signal line.

In FIG. 2, numeral 5 indicates a data signal line indicating the type of data, the number of ζ-data, or the content of the data.

In FIG. 3, 6 is an address signal line indicating the type of data, 7 is a readback address signal line that returns 6, and 8 is a readback address signal line that returns 6.
9 indicates a data signal line indicating the content of data corresponding to 6, and 9 indicates a readback data signal line that returns 8.

Regarding the number of address signal lines and data signal lines mentioned above, as a general rule, both address signal and data signal lines are 1.
Assuming that there are 6 bits and the parity pit is 1 bit,
Bits 3 and 4 are made up of 17 bits, and bits 5, 6, 7, and 8.9 are made up of 16 bits.

Next, the operation will be explained.

In FIG. 1, a transmitting program control device 1 places a generated address signal indicating the type of data and a parity bit on an address signal line 3, and generates a data signal and a parity bit corresponding to 3 on a data signal line 4. The received program control device 2 is then sent to the program control device 2 on the receiving side.

In step 2, the transmitted address signal and data signal are read and a 17-bit parity check is performed on each to check whether the data is transmitted correctly or not.

In FIG. 2, the transmitting side program control device 1 connects the data signal line 5
The receiving side program control device receives an address signal indicating the type of data, a data length signal indicating the number of data, a data signal indicating the contents of the number of data specified by the data length signal, and a checksum signal of the sum of the above data. 2 sequentially.

In step 2, the transmitted data is sequentially read, and finally a sum check is performed to check whether the data is transmitted correctly or not.

In FIG. 3, the transmitting side program control device 1 puts an address signal indicating the type of data on the address signal line 6, puts a data signal corresponding to 6 on the data signal line 8, and transmits it to the receiving side program control device 2.

2 reads the transmitted address signal and data signal, then puts the address signal on the readback address signal line 7, puts the data signal on the readback data signal line 9, and sends it back to 1.

In step 1, the readback address signal and the readback data signal are read and compared with the previously transmitted address signal and data signal to check whether the data transmission is correct or not.

Since the conventional data transmission control system is configured as described above, it has the following drawbacks.

In FIG. 1, since a parity check method is used, extra parity bits are required for each of the address signal line and the data signal line.

Furthermore, when generation and checking of parity bits are performed by program processing, the program processing for data transmission control becomes complicated.

Also, if the parity bits are generated and checked in hardware, the circuit configuration becomes larger! Become.

In FIG. 2, since there is only one type of data signal line, it is necessary to determine whether it is an address signal, data length signal, data signal, or checksum signal for each transmission order, which makes the program processing complicated.

Furthermore, since it uses a checksum method, it has the disadvantage that even if one of the data signal lines is disconnected, an error in data transmission cannot be detected.

In FIG. 3, the data transmission method is easy and error checking is completely performed, but there is a drawback that the configuration of signal lines is large.

This invention has been made to eliminate the drawbacks of the conventional ones as described above, and the data transmission is improved by logically combining the readback address signal line 7 and the readback data signal line 9 shown in FIG. The present invention provides a data transmission control method that is easy to perform and can also easily check for transmission errors.

An embodiment of the present invention will be described below with reference to the drawings.

4
In FIG. 4, reference numeral 10 indicates a readback signal (16 bits) line in which the address signal and data signal read in step 2 are grouped together with a certain logic and sent back to step 1.

In FIG. 4, the exclusive OR of the data read from the address signal line 6 and data signal line 8 for each bit is transmitted to the readback data signal line 10.

FIG. 5 shows a truth table for exclusive OR.

1 sent data through 62 and 8 to A and D.

Assuming that the data received by 2 through 6 and 8 are A' and D', the data transmitted by 2 through 10 is E, and the data received by 1 through 10 is E', the following equation holds true.

E=A'■D' Here, only when A←A, 'D'=D, E'=E, E'■A=E■A-(A'■D/)■A=
A■D■A =D or E[stock]D=E■D=(A lampΦsu■D=A■D■
The relationship D=A holds true.

That is, 1 takes the exclusive OR of the address signal A transmitted through 6 and the data E' read through 10, and compares it with the data signal transmitted through 8, or compares it with the transmitted data signal and the reply data E'. Find the exclusive OR of
By comparing with the transmission address signal A, errors in signal transmission can be detected.

Although the above embodiment is limited to data transmission from 1 to 2, it can also be applied to the case where data addressed by 1 is received from 2.

As described above, according to the present invention, by logically combining address signals and data signals in a data transmission method between program control devices, the system configuration is simple, program processing is easy, and transmission reliability is achieved. It has the effect of obtaining something with high sexiness.

[Brief explanation of the drawing]

Figures 1, 2, and 3 are system configuration diagrams showing conventional data transmission control methods, Figure 4 is a system configuration diagram according to an embodiment of the present invention, and Figure 5 is the truth value of exclusive OR. It is a diagram. In the figure, reference numeral 1 designates a transmitting prologue device, 2 a receiving program device, 6 an address signal line, 8 a data signal line, and 10 a return data signal line. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] 1. In a method for detecting errors in transmission of address signals and data signals transmitted and received between programming devices,
The receiving side programming device obtains an exclusive OR signal of the received address signal and the received data signal and returns it to the sending side programming device, and the sending side programming device combines this returned exclusive OR signal with the sending signal. A method for detecting errors in signal transmission, characterized in that an exclusive OR signal with an address signal (or a transmitted data signal) is obtained, and this is compared with the transmitted data signal (or a transmitted address signal) to check for identity.