Development Of JHP-2000 High Precision Isolated Multi-channels Data Acquisition Device

In this paper,the research of the principal and subordinate system of the high precision data acquisition device(JHP-2000) is expatiated in detail.The instrument adopts 89C52 of Atmel Co.as MCU and uses the ADC-AD7714 as A/D converter,which make the accuracy of data acquisition achieve 0.1%FS or better.The instrument has eight channels,and every channel uses dry-reed relays to achieve isolated absolutely.There are 1,2,4,8,16,32,64,128 eight selectable gains provided at the input end of every channel in the device.According to the gain,the voltage can be set independently from 15mV to 100V.The speed can reach 25Hz when collecting with only one channel,and can reach 2.5 seconds/8 channels when collecting with eight channels.The 1mA current source is designed in the instrument for thermal-resistance temperature measurement.The data is transmitted to computer by isolated RS-232 interface.The device is entirely isolated from computer at electric,which reinforces the stabilization and security of working on device.Author explains self-defined serial-communication protocol in detail in the paper.The disposal software of data acquisition is developed with VB.The parameter setting of data acquisition is finished by computer,and computer can read the parameter of the device at any moment also.Real time data collected by collector are transmitted to computer and then are displayed.In this paper,clueing on the basic procedure of designing a high precision data collector,author expatiates the process from pre-research,lay outing of function, software and hardware designing to debugging,developing sample of instrument.In the end,the whole paper is summarized.