Variable-length data transmission method in access control system

Abstract

The invention discloses a data transmission method in an access control system. The data transmission method comprises the following steps of: sending a protocol data unit by using an access controller, wherein the protocol data unit consists of a synchronization header, a protocol information header, a data length information unit, a data unit and check bytes sequentially; verifying the synchronization header and the protocol information header by using a computer host; reading length data of the data unit after the synchronization header and the protocol information header are qualified in the validation; judging whether the length data of the data unit is equal to data in the data length information unit; receiving the data unit and the check bytes if the length data of the data unit is equal to the data in the data length information unit; performing CRC (cyclic redundancy check) to ensure the validity of received data; processing the data unit if the data is correct in the check;and otherwise, finishing the transmission. According to the data transmission method, various kinds of data can be flexibly transmitted, the electromagnetic anti-jamming capability can be improved, data is difficult to lose in the process of data transmission, the coupling of data synchronization is reduced, and the receiving of effective data is improved.

Description

technical field [0001] The invention relates to a data transmission method, in particular to a variable-length data transmission method applied in an access control system. Background technique [0002] In recent years, due to the continuous improvement of the market's requirements for electronic equipment, and the electronic equipment industry is also striving for excellence, and continuously develops various new products with powerful functions, which makes electronic equipment more and more complex. Many electronic equipment are equipped with Communication protocols are used for data transmission. [0003] The format of most of the access control communication protocols used in the access control system is a fixed-length data format. For the application scenarios of the electric power industry with multiple applications, such data has very large limitations, which have great restrictions on the transmitted data and cannot be flexible. Second, the synchronization header o...

AI Technical Summary

Problems solved by technology

[0003] The format of most of the access control communication protocols used in the access control system is a fixed-length data format. For the application scenarios of the electric power industry with multiple applications, such data has very large limitations, which have great restrictions on the transmitted data and cannot be flexible. Second, the synchronization header of the access control communication protocol often uses a single-byte synchronization header 0x7E. In the application of the power industry, the electromagnetic interference caused by the special power environment is more serious than other occasions, and it is easy to cause data loss in the data transmission process, and Bytes such as 0x7E are also more common in the network, which makes the verification judgment after data reception prone to deviation, resulting in a higher frequency of received error data and lower communication efficiency