本文详细介绍了低通滤波器的数学模型及其滤波的仿真效果,而后介绍了对其进行数字化的过程,并给出了这种数字滤波器的PLC 程序,最后介绍了这种数字滤波器在低压铸造温度采样中的应用。应用实践表明,这种数字滤波的效果是相当好的。 关键词:低通滤波器,模拟信号,低压铸造,PLC Abstract: This paper describes in details the mathematic model and simulating result of the low pass filter . And this paper discusses how to numbering the filter and make the PLC program of filter . Finally , the paper introduces the its application to low pressure casting temperature sampling . The practice result shows that the effect of numerical filter is quite good . Key words : low pass filter ; analog signal ; low pressure casting ; PLC