Research Of Smart Networked Transducer Based On CAN Fieldbus

There were many control networks such as CAN, PROFIBUS, FF and so on at the present time. Interfacing transducers to all these control networks and supporting the wide variety of protocols represented a significant and costly effort to transducer manufacturers.In order to facilitate the support of multiple networks and enable plug and play at the transducer (sensor or actuator) level, a smart networked transducer in conformance with the IEEE 1451.1 and IEEE 1451.2 was designed adopting Object-Oriented method in this project.The transducer was divided into three distinct sections: the Smart Transducer Interface Module (STIM) including a temperature and an emitting LED, the Network Capable Application Processor (NCAP) which obtained the transducer data from STIM and connected to the CAN fieldbus, and a 10-lines Transducer Independent Interface (TII) which connected STIM with NCAP. The ADμC 812 microcomputer was designed as Smart Transducer Interface Module , the AT89S52 microcomputer and the CAN interface was designed as Network Capable Application Processor.A research was also made on the Real-time performance of CAN especially when there were many network errors during the communication of CAN system. First we adopted the method of probability to set the delay time due to tolerable errors. Then the worst case transmission time of the CAN node was calculated. If the message's transmission time exceeded the latest transmission time, it would be aborted for the real-time property of the lower priority message. And some experiments were made to verify this processing mechanism.The designed smart networked transducer based on CAN realized transducers-to-network interchangeability and interoperability, and it would be good for updating and maintaining of the measuring and controlling system. The research about the network errors processing mechanism also would have reference value for real application.