通过A/D读入模拟信号转换成数字量,存入51单片机或可用外扩存储,并通过D/A从存储单元每2S从新转换一组数据,并在2S期间一直显示上次读入的信号,达到存储的效果.-A/D reading　the analog signals and changes into digital, store into 51 single-chip or extended outside store,then by D/A get from the storage unit ,show the last time period signal for 2s to achieve the effect of storage.