Development Of FCS Control System Based On CAN Bus

Fieldbus is a digital, bi-directional, poly-branched communication network connecting field devices in automation control system. It highly integrates of computing technology, communication technology and control technology. It is one kind of open and distributed fieldbus. Fieldbus is a frontier of developing automation technology.In the dissertation the beginning, concept, system structure, features and history of fieldbus are summarized; the advantage and disadvantage of several common fieldbuses are analyzed; and a prototype of FCS based on CAN bus is proposed. The FCS system consists of one upper PC and several fieldbus modules. The upper PC can be realized with a traditional PC or the special record module designed in the dissertation, which can record, input and display.The FCS system consists of a record module which records alarms data and manages bus communication affairs, analogue input modules, analogue output modules, digital output modules, and a voice alarm module. With other modules also scheduled, each is developed with embedded MCU LPC2119 of which the function interfaces are extended. The CAN bus communication protocol is composed, with the netcard driver programmed.Based on LPC2119 are the modules developed. LPC2119 is an embedded MCU with ARM7 core, 128KB embedded high speed flash memory, 16KB on-chip static RAM, very tiny package with 64 pins, 4-channel 10-bit A/D converters, and 2 CAN interfaces, very fit for industrial applications.The working plan of the system: After each module is installed in the field, they are configured with an upper PC or the record module. When the configuration is complete, system runs independently. The record module manages lower modules periodically, receives and records alarm messages sent through the bus, outputs control commands to control modules according to configuration parameters, controls related executive modules. The parameters of the bus nodes can be setup and displayed through the record module.The test of the FCS shows that the design plan is correct and realizes the design requirements.