Real-time communication method used for programmable logic controller and personal computer

Abstract

The invention provides a real-time communication method used for a programmable logic controller and a personal computer. The real-time communication method is characterized in that every time when the connection between the programmable logic controller and the personal computer is reestablished, the calling part of the programmable logic controller and the personal computer is used to transmit a sequence number reset message, and the confirmation of the called party can be carried out by transmitting a sequence number reset reply message; during the connection period, whether the communication between the calling party and the called party is normal can be determined by the handshake message; only when the communication is normal, the calling party is used to transmit the message according to the priority of the message, and only when the last calling replay message of the called party is received, the calling party is used to transmit the new calling message.

Description

technical field [0001] The present invention relates to the field of industrial communication, and more particularly to the special application of communication between industrial equipment and information technology equipment. Background technique [0002] In the current field of industrial control, there are various communication methods between programmable logic controller (PLC) and personal computer (PC), and the communication protocol can also ensure the real-time and reliability of communication more completely. But the premise is that industrial control software and industrial boards need to be installed in the PC, which will bring certain side effects in some special applications. For example, if the PLC communicates with a PC running image processing, and additionally runs industrial control software or industrial control boards in the PC, on the one hand, the operating capacity of the CPU resources of the PC will be insufficient; brings many changes. [0003] In...

AI Technical Summary

Problems solved by technology

[0004] 1. Unreliable control command transmission: control command transmission needs to be based on a stable and reliable communication protocol, but the existing standard communication ports, such as RS232 serial port (or RS422 / RS485) communication is unreliable transmission, so it needs to be based on this Reliable Data Transfer Protocol

[0005] 2. There is no relevant processing mechanism for abnormal notification protocols such as safety interlocking

[0006] 3. The system modules do not have a unified communication layer, which leads to the inability to reuse the codes of the communication modules of different products, and the coupling between the application protocol layer and the communication layer is too strong

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