| With people’s focus on strengthening the safety and the development of functional safety technology,a lot of functional safety products have been widely used in industrial production in foreign country.And recent years, the demand for functional safety products is booming in the domestic.Be badly in need to research and develop the functional safety products with ind ependent intellectual property rights in our country.First,this paper studies the technology of functional safety, mainly including functional s afety, risk assessment, safety integrity level and life cycle.On this basis, the demand for functi onal safety temperature transmitter design and the structure of the functional safety instrument is analyzed, and design a functional safety temperature transmitter with SIL2.1oo1D structure is used in the temperature transmitter by optimizing choose diagnostic function to increase the risk of diagnosable dangerous failure rate,so as to improve the diagnostic coverage and safety failure points,at the same time reduce the design cost in order to improve the competitiveness of the products.The transmitter uses modularization design method, including the basic module design and the diagnostic module design. The basic module includes clock, MCU, signal input, AD conversion, DA conversion and power protection. The diagnostic module includes watchdog clock diagnosis, wire break diagnosis, AD out of the chip diagnosis, AD on the chip diagnosis and the MCU’s self-diagnosis. Every module has specific, clear function, and they connect each other by different standard methods of communication. Besides, host computer software is designed to configure different kinds of sensors before officially leaving factory and reduce transmitters’error causing by using different components. At last, use FMEDA and fault insertion trial to test the instrument. The actual test results indicate the functional safety transmitter designed in the paper meets SIL2requirements. |
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