In order to improve the anti interference ability of the intelligent instrument, a kind of data input channel which is based on V/ F transducer, RAM data power dump protective circuit and scheme of design for software watchdog are proposed. 为提高智能仪表的抗干扰能力,提出了一种基于V/F变换器的数据输入通道、RAM数据掉电保护电路以及软件WATCHDOG的设计方案。