PLC control system and PLC extension bus implementation method

Abstract

The invention discloses a PLC control system, which comprises a PLC and a plurality of extension modules, wherein the PLC is cascaded with the plurality of extension modules by adopting extension buses; the PLC comprises a microprocessor and a first extension bus transceiver, the microprocessor is used for controlling communication between the PLC and the plurality of extension modules, and the first extension bus transceiver is used for exchanging data with the first stage extension module through a PLC rear bus interface; and each extension module comprises an extension microprocessor and a second extension bus transceiver, the extension microprocessor is used for controlling communication between the extension module and the PLC, and the second extension bus transceiver is used for exchanging data with the previous stage extension module or the PLC through a corresponding stage front bus interface and exchanging data with the next stage extension module through a corresponding stage rear bus interface. The invention further discloses a corresponding PLC extension bus implementation method. Through implementing the technical scheme of the invention, the speed of a PLC extension bus can be increased, the cost is reduced, and the anti-interference capability in the sampling process is high.

Description

technical field [0001] The invention relates to the field of programmable logic controllers (ProgrammableLogic Controller, PLC), in particular to a PLC control system and a method for realizing a PLC expansion bus. Background technique [0002] In the prior art, PLC is to expand I / O (Input / Output, input or output) points or functions. Generally, various I / O modules or functional modules need to be connected through an expansion bus to form a PLC control system. The expansion bus communicates with I / O modules or function modules. [0003] Existing PLCs and expansion modules use expansion buses such as serial peripheral interface (serial peripheral interface, SPI) or controller area network bus (ControllerAreaNetwork, CAN) for connection and communication, but in the prior art, in some cases , the rate of the expansion bus itself is relatively high. Under the requirement of low cost (for example, the microprocessor using LCMO2), since the system does not allow higher frequenc...

AI Technical Summary

Problems solved by technology

[0003] Existing PLCs and expansion modules use expansion buses such as serial peripheral interface (serial peripheral interface, SPI) or controller area network bus (ControllerAreaNetwork, CAN) for connection and communication, but in the prior art, in some cases , the rate of the expansion bus itself is relatively high. Under the requirement of low cost (for example, the microprocessor using LCMO2), since the system does not allow higher frequency multiplication, there is no way to realize the data transmitted between the PLC and the expansion module for multiple times. Sampling and filtering processing can only perform single-point sampling, so errors are prone to occur and the anti-interference ability is poor

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