Rapid communication structure and rapid communication method for multiple upper computers and controller based on RS485 bus

Abstract

The invention relates to the field of industrial communication, and discloses a rapid communication structure and a rapid communication method for multiple upper computers and controllers based on an RS485 bus, the controllers are powered on for the first time, data are sent to the upper computers in a broadcast mode, the data are transmitted in one step, and the time for polling the controllers one by one by the upper computers is saved; in the subsequent operation process, the controller only broadcasts changed data, and a large number of bus resources occupied by unchanged data communication are saved; meanwhile, the controller can respond to a request command and a value writing command of the upper computer to all data, and value writing of the upper computer adopts a message queue to ensure that the value writing command is not lost; most importantly, the controller and the upper computer respectively carry out CRC verification on all data of the computer, if the data are not consistent, the controller broadcasts all data again, and the consistency of the data of the controller and the upper computer is ensured. By using the communication method, on the premise of ensuring the data consistency, the communication speed of the upper computers and the controller can be greatly improved, and the more the upper computers are, the more obvious the effect is.

Description

technical field [0001] The invention relates to the field of industrial communication, in particular to a fast communication structure and method for a plurality of upper computers and controllers based on RS485 bus. Background technique [0002] At present, based on the 485 bus request response communication, the most common and mature one is the modbus protocol. The modbus protocol is a master / slave architecture protocol. The master-slave protocol strictly follows the request response mechanism. When there are multiple modbus host computers, the host computer The instructions for reading and writing the controller cannot be used at the same time. Only after the instruction of the previous upper computer is executed, the control right is delivered to the next upper computer, and the instruction of the next upper computer can be executed, even if only the same frame of data of the controller is read. , each host computer has only one read command, if there are 100 host compu...

AI Technical Summary

Problems solved by technology

[0002] At present, based on the 485 bus request response communication, the most common and mature one is the modbus protocol. The modbus protocol is a master / slave architecture protocol. The master-slave protocol strictly follows the request response mechanism. When there are multiple modbus host computers, the host computer The instructions for reading and writing the controller cannot be used at the same time. Only after the instruction of the previous upper computer is executed, the control right is delivered to the next upper computer, and the instruction of the next upper computer can be executed, even if only the same frame of data of the controller is read. , each host computer has only one read command, if there are 100 host computers, the average time for each host computer to finish reading is calculated as 20ms, then the cycle of polling once is also 20*100=2000ms; The read and write cycle of the controller to the controller is much longer than 20ms. Therefore, the polling cycle is too long, the controller data collected by the host computer is quite different, the real-time performance is not good, and the response of the whole system is slow.

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