可编程控制器串行A／D、D／A接口电路的研究与应用

Research And Application of one kind of Series A/D or D/A Interface in Programable Controller

从Ｖ／Ｆ（电压／频率）转换电路入手，结合可编程控制器中高速计数器及频率输出指令的特点，分别研究并设计了一种可以用可编程控制器的开关量输入口和输出口分别实现Ａ／Ｄ或Ｄ／Ａ转换的接口电路，并研究了相应的程序设计方法。该接口电路的最大特点是一个Ａ／Ｄ或一个Ｄ／Ａ通道，仅占用可编程控制器的一个开关量输入点或输出点，从而大大减化了接口电路的结构。

This paper studies and designs one kind of series interface to realize the A/D or D/A conversion at the input or output end of programable Controller(PLC),which is started from V/F conversion circuit with the characteristic of the high-speed counter in PLC,and related program design methods.The main feature of the interface is an A/D or D/A channel,using only one on/off input or output point,so that the interface structure is greatly simplide and the cost is therefore lowered.