Industrial Field Data Acquisition System Design Based On CAN Bus

CAN bus is a mature fieldbus with the ability of real-time and high reliability. And ithas been widely used in industrial fields. The thesis designed an industrial field dataacquisition system based on CAN bus.The communication protocol was designed based on CAN2.0B protocol. The thesisdesigned upper layer called transport layer and application layer. Transport layer definedmessage unpacking method and fragment reassembling method due to short frametransmission characteristic of CAN bus protocol. And the application layer defined systemfunctions and protocols associated. The physical layer of the communication protocol wascompatible with ISO11898standard. By analyzing the development of modern industrialfield data collection technology trends, the thesis designed an industrial field datacollection system composed of a master controller and distributed data acquisition devices.Combining with the industrial field sensor output signal characteristics, a common analogsignal conditioning circuit was designed. This conditioning circuit was used as the analogfront end of distributed data acquisition devices. And in order to further improve themeasurement accuracy of the analog signal input, the thesis invented an adaptivecalibration strategy to compensate the environment temperature drift. Data acquisitiondevice utilized Cortex-M3microcontroller as the controller, and utilized an open operationsystem called FreeRTOS as software platform to develop the software. In order to meetthe real-time requirements of CAN communication and provide a friendlyhuman-computer interaction, the main controller used an embedded Linux operatingsystem as software platform. The hardware of the main controller used the ARM11microcontroller as the microprocessor. Then the thesis completed transplantation of theembedded Linux OS, Linux driver design and user application design for the maincontroller. The industrial field data acquisition system has met the design specifications withstrong scalability and flexibility. The hardware platform of the system can be widely usedin industrial field data acquisition.