| This paper, based on connecting both here and abroad research reports, research papers and some other information, analyses and dissertates functions and specialties about the field bus and the CAN protocol. Then an accessible system which applies CAN bus communication to smart instruments is designed. We introduce particularly the communicating process of smart instruments with the CAN bus. And we make a design after studying deeply on MCU-PIC18F458 which integrates CAN controller. This system has many merits. The system of smart instruments has simple structure, small size, high reliability and stability. Besides, it's easy to use, flexible application, lower cost, multifunction and it uses plenty limited space in smart instruments. All of these enhance the smart instruments' advantages on market competition and greatly accelerate its application intelligent, scientific and standardized process .The following aspects in my thesis are innovative or improved:It is taking the lead of using the MUC(PIC18F458)with CAN module for smart instruments in industry in the Asia-Pacific region.The design of the CAN bus communication: It applies the CAN protocol to MCU(PIC18F458)which is with the CAN module and design a bidirectional communication system which is from one node to two nodes.The design of LCD liquid crystal display on lower computer: the design makes the serial communication between two different MCU (PIC and MCS-51)coming true. To design like this is in order to enlarge I/O port of MCU-PIC18F458 for driving metrical values of LCD and setting temperature values. In addition, we also validate the feasibility of exchanging data between two different kinds of MCU in smart instruments system.The design of LED floating-point display: It uses the SPI module function of MCU-PIC18F458 and the characters of 74HC595 to drive LED for displaying the voltage value.The design of serial communication between upper-PC and lower-PC: It carries out communication between PC and the CAN bus by serial port of PIC18F458.The design of conditioning circuit from sensor: It connects analog signals, then filters the waves, magnifies and transmits the analog signals, at last displays them.The design of up-PC display and remote control:It builds a measuring and controlling the CAN bus network which can display the voltage values or temperature values on PC and compares them with the setting values to control Implementing agencies' working.Call Matlab programmers in Microsoft Visual Studio .NET: In order to draw the measurement Dynamic Curve of temperature and pressure and display their values on different time, it needs to call Matlab engineer and Matlab function Plot in Microsoft Visual Studio .NET . |
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