JPH05219043A - Frame synchronous type data transfer system - Google Patents

Abstract

PURPOSE:To easily structure and expand the system by adding individual number information on an opposite party at the head of a frame and a check sum word at the tail. CONSTITUTION:A transmission frame generating means adds the ID word 10 indicating the individual number of the transfer destination at the head of an information word 30, performs binary addition in word units from the ID word 10 to the tail information, and adds the low-order 8 bits of the addition result as the check sum word 20 behind the tail information word to constitute one frame. A reception frame synchronizing means performs sequential binary addition in word units from the 1st received word and judges that a received word which arrives next is the head of the frame when the value of the low-order 8 bits of the addition result at the point of time of the addition matches the word which is received next. When not, on the other hand, it is judged that the frame synchronism steps out, the 1st word of a reception frame which is expected next is shifted forward or backward, and this operation is repeated until they match each other.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame synchronizer, and more particularly to a frame synchronizer in start-stop synchronous serial data transfer.

[0002]

2. Description of the Related Art Generally, in a serial data transfer method in which a plurality of consecutive words are used as one information unit (frame), it is necessary for the receiving side to find the beginning of a frame in order to correctly receive and restore transmitted information. The method of finding the beginning of a frame is called the frame synchronization method.

A conventional example is shown in FIGS. Conventionally, a special frame word 40 is determined for frame synchronization, and it is added to the head of the information word 30 as shown in FIG. 4, and this is regarded as one frame and connected to the destination as shown in FIG. It was output to the transmission line. As the frame word 40, "11111111" is often used as shown in the frame word of FIG.

Here, in order to prevent the information word 30 from being coincident with the frame word 40, one bit in one word of the information word is always fixed regardless of the information content as shown in the information word of FIG. There is. In this conventional example, since the frame word 40 is "11111111", the 8th bit is fixed to 0 as shown in the information word of FIG.

On the receiving side, frame synchronization is realized by finding the frame word 40, that is, "11111111".

[0006]

However, in the above-mentioned conventional example, since one bit in one word of the information word is prohibited from being used, there is a disadvantage that the transmission efficiency is lowered.

In addition, it is commonly used in computers 8
In the start-stop synchronization method in which the number of bits is 1 word, the information word is limited to 7 bits, and thus there is a problem that the compatibility with a normal computer is deteriorated.

Further, since it is not possible to specify a transfer partner, when there are a plurality of transfer partners, as many transfer lines as the transfer partners are required as shown in FIG. There was a problem that it could not be performed easily.

[0009]

SUMMARY OF THE INVENTION It is an object of the present invention to improve the inconvenience of the conventional example, and particularly in the frame synchronization method of the asynchronous transfer serial transfer, the transmission efficiency is excellent and the system can be easily constructed and expanded. It is to provide a frame synchronous data transfer system.

[0010]

In view of the above, in the present invention, a plurality of consecutive words are treated as information units (frames) in a start-stop synchronization serial data transfer system for transferring N bits of a digital data code in units of one word. In the data transfer method, the individual number information of the receiving party is given to the word located at the beginning of the frame, and the lower N bits of the addition result in word units from the word located at the beginning of the frame to the information word located at the end The (checksum word) is added to the position of the word next to the information word located at the end of the frame to form one frame. This aims to achieve the above-mentioned object.

[0011]

In the transmission frame creating means, an ID word indicating the individual number of the transfer partner is added to the head of the information word, and further the ID word to the last information word are sequentially binary-added in word units. The lower 8 bits are added as a checksum word after the final information word to create one frame of transmission data. Then, the transmission data of one frame is sequentially transmitted word by word from the head ID word to the checksum word from the serial port on the transmission path.

In the reception frame synchronization means, the first received word is sequentially subjected to binary addition in word units, and the value of the lower 8 bits of the addition result at the time of addition is compared with the next received word, and the comparison is made. If the results match, the next received word is judged to be the beginning of the frame, but if the comparison results do not match, it is judged that the frame synchronization has been lost, and the next expected received frame The first word is shifted forward or backward by one word, and the received words are sequentially binary-added again, the lower 8 bits of the result are compared with the succeeding received words, and this is repeated until they match. When frame synchronization is established, the first word is checked, and if it is judged that the data is addressed to itself, this received frame is taken in, but if it is judged that it is not addressed to itself, this received frame is discarded.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

An ID word 10 indicating the individual number of the transfer partner is added to the beginning of the information word 30, and the ID word 10 to the last information word are binary-added in word units and the lower 8 bits of the addition result are checked. A transmission frame creating means that adds one frame after the final information word as a thumb word 20 and a value of the lower 8 bits of the addition result at the time when the binary addition is sequentially performed in word units from the first reception word. If the comparison result of the next received word matches, it is determined that the next received word is at the beginning of the frame, and if the comparison result does not match, it is determined that the frame synchronization is out of sync. The first word of the expected received frame is shifted forward or backward by one word, and the words are binary-added again.
It comprises a reception frame synchronization means for comparing the bit with the next reception word and repeating this until a match is found.

Next, the operation of this embodiment will be described. However, it is assumed here that the information word 30 is composed of m words. In addition, as shown in FIG.
And device B (1) and device B (2) ... device B (n)
Are connected by one transmission line, and here, as an example, a case where data is transmitted from the device A to the device B (2) will be described.

In the device A, an ID word 10 indicating the individual number of the transfer partner, that is, the device B (2), is added to the head of the information word 30 composed of m words as shown in FIG. Is further added, and the ID word 10 to the last information word, ie, the mth word, are binary-added sequentially in word units, and the lower 8 bits of the addition result are used as a checksum word 20 for the final information word, that is, the mth word. Append later and add m + 2 words to 1
Let it be a frame.

Further, here, as shown in FIG. 2, one word is composed of 8 bits, to which a 1-bit start bit is added at the beginning and a 1-bit stop bit is added at the end. There is. However, the stop bit is not limited to 1 bit, and 1.5 bits or 2 bits may be added.

In the device A, the transmission frame creating means 1
When the transmission data of the frame is created, it is transmitted from the head ID word 10 word by word from the serial port on the transmission path as shown in FIG.

In the devices B (1) to B (n), when a signal is received via the transmission path, the received frame synchronization means sequentially performs binary addition in word units from the first received word, m + 1. Number of received words are added, the lower 8 bits of the addition result is compared with the binary code value of the next received word, and if the comparison result is the same, the next received word is the next received word. Judge that it is the beginning of the frame.
If the value of the lower 8 bits of the addition result at the time of addition is compared with the binary code value of the word received next, and if the comparison result does not match, it is determined that the frame synchronization is shifted, 1 for the first word of the next expected received frame
The word is shifted forward or backward, and m + 1 received words are sequentially binary-added again, and the lower 8 bits of the result are added by m.
Compare with the binary code value of the received word following the + 1st word,
Repeat this until it matches.

After the frame synchronization is established, the head word is checked, the device B (2) judges that the data is addressed to itself, and fetches this frame, but the device B (1) and the device B (3) The device B (n) determines that the data is not addressed to itself and discards this frame.

[0021]

Since the present invention is constructed and functions as described above, according to the present invention, it is not necessary to provide the use prohibition bit in the information word and the transfer partner can be designated.
For this reason, it has excellent transmission efficiency, and since it is possible to communicate with a plurality of other parties through a single transmission path, it is possible to easily construct and expand the system, which is an unprecedented excellent frame synchronous data transfer method. Can be provided.

[Brief description of drawings]

FIG. 1 is a frame configuration diagram showing an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an example of one word in FIG.

FIG. 3 is an explanatory diagram showing an example of a device configuration according to the present invention.

4 to 5 are frame configuration diagrams showing a conventional example.

FIG. 6 is an explanatory diagram for explaining a device configuration in a conventional example.

[Explanation of symbols]

 10: ID word 20: Checksum word 30: Information word

Claims (2)

[Claims] 1. A start point of a frame in a data transfer method in which a plurality of consecutive words are handled as an information unit (frame) in a start-stop synchronization serial data transfer method for transferring N bits of a digital data code in 1-word units. The individual number information of the other party receiving the information is given to the word, and the lower N bits (checksum word) of the addition result in word units from the word located at the beginning of the frame to the information word located at the end are added to the end of the frame. A frame-synchronous data transfer system characterized in that one frame is formed by adding it to the position of the next word of the positioned information word. 2. An ID word indicating the individual number of the transfer partner is added to the beginning of the information word, and the ID word to the last information word are binary-added in word units, and the lower 8 bits of the addition result are a checksum. A transmission frame creating means for adding one frame as a word after the final information word is provided, and binary addition is sequentially performed word by word from the first received word and the value of the lower 8 bits of the addition result at the time of addition and the next If it does not match, the next word is judged to be the beginning of the frame, and if it does not match, it is judged that the frame synchronization has shifted and the first word of the next expected received frame. Is shifted forward or backward by one word, and binary addition is performed again, and the lower 8 bits of the result are repeated until they match the next received word. A frame-synchronous data transfer method characterized in that the above are synchronized.