Communication system design based on PLC composed of LPC2478+FPGA

摘要

The paper designs a kind of communication system based on a new type Programmable Logic Controller (PLC) composed of LPC2478+FPGA and CAN bus is used as the system communication mode. Based on the analysis of the basic structure of the PLC and the communication features, the identifier customization method is used to design CAN protocol aiming at requirements for system communication features; the data types are divided into control command type, common data type, logical type and PLC instruction type for the features of complex data; identifier of demanding higher real-time data is set lower and use real-time operating system μC/OS-II for the features of real-time communication; LPC2478''s FULLCAN mode is used to accept data and a circular queue is used to save it for the features of a large number of PLC user program. The result shows that the CAN communication design can achieve real-time and reliable communication of a large number of complex data from multi-node in the new type PLC system.