三、可编程控制器的模拟量控制可编程控制器除完成开关量控制外,模拟量控制也较常见,一般大中型机都具备模拟量控制,目前发展趋势是中小型机也逐步增加了模拟量控制功能,为此本讲座将详细讨论PLC的模拟量控制。1.模拟量控制的原理PLC的模拟量控制系统一般具有两种类型:即BCD型及直接数字型。BCD型模拟量控制系统的原理示于图1。图中左 Third, the programmable logic controller programmable controller addition to the completion of the switch control, the analog control is more common, generally large and medium-sized machines are equipped with analog control, the current trend is to gradually increase the small and medium-sized computer simulation Volume control functions, this seminar will discuss in detail PLC analog control. 1. The principle of analog control PLC analog control system generally has two types: the BCD type and direct digital type. The principle of the BCD analog control system is shown in Figure 1. Left in the figure