System Realization And Accuracy Analysis Of Intelligent Multimeter

Intelligent multimeter is a kind of high-quality digital meter with microprocessor or microcontroller, which is a new-type instrument of hardware and software integration, and software determine the level of the smart meter equipment. Its main advantage is high accuracy, strong function, automatic calibration, automatic measurement, and automatic data processing capabilities. It could communicate with a computer using RS-232or IEEE-488standard interface to complete automatic testing and real-time control.Study object of this topic is a certain type of multimeter NB80000, whose analog front end is multimeter special chip FS9704. Microprocessor FSμP01control FS9704measure input signal, and then process the measurement. Finally, display the result with LCD.This multimeter system controled by general microcontroller is mainly composed of measuring module, microcontroller module, storage module, communication module, gear selecting module and display platform based on Lab VIEW. Microcontroller, C8051F020, as the control-core of the system read corresponding data from storage module after gear selecting module selected gear, and then generate control signal to control measuring module measure input signal. Finally, display the result in the display platform based on LabVIEW. This paper constituted by following several parts:The second chapter is multimeter’s composition and working principle.Firstly, the conception, features and general composition of intelligent instrument are introduced.And then take example for NB80000, introduce multimeter’s overall composition and basic working principle, and provide the schematic circuit diagram of each module and core components’function.Finally, introduce the application of virtual instruments and compare the difference between traditional instruments and virtual instruments. Moreover, the function of LabVIEW is also introduced.Design and implementation of multimeter system under the control of general microcontroller is introduced in the third chapter.First, according to intelligent multimeter’s general framework, construct multimeter system under the control of general microcontroller with referring to the stricture of NB80000.Then, introduce the design and implementation methods of each module, and discuss specially the central problems. Measuring module mainly completes the signal under test conditioning and analog-digital conversion. Storage module is used to store relational data which is necessary for system work. Communication module completes data exchange with PC. Gear selecting module is used to receive gear switching command in order to realize gear selection. Microcontrollor module controls measuring module completing gear switching and realizes measurement convertion on the one hand. On the other hand, realizes control of storage module, communication module and gear selecting module. Display platform based on Lab VIEW is a integrated platform. Gear selection and measurement display could be realized after sending of gear switching commands and measuring commands. Meanwhile, function keys’ pressing could realize range conversion, data hold, relative measurement, timing and other functions.In the fourth chapter, integrated all modules to make up multimiter system with C8051F020as the core of the system. Then, write calibration software program in order to perfect systematic function. And then completed a comprehensive test of the calibrated system and achieve performance evaluation of the system.