使用PLC的自动化制造系统——2.1.4 梯形逻辑输入

2.1.4 Ladder Logic Inputs
2.1.4梯形逻辑输入

 

    PLC inputs are easily represented in ladder logic. In Figure 2.11 there are three types of inputs shown. The first two are normally open and normally closed inputs, discussed previously. The IIT (Immediate InpuT) function allows inputs to be read after the input scan, while the ladder logic is being scanned. This allows ladder logic to examine input values more often than once every cycle. (Note: This instruction is not available on the ControlLogix processors, but is still available on older models.)

     

     PLC的输入是很容易用梯形逻辑图表现的。在图2.11显示了三中输入类型。前两个是前面讨论过的常开和常闭输入。 IIT（立即输入）函数允许梯形逻辑正在被扫描时，在输入扫描后即被读入。这使得梯形逻辑研究在每个循环不止一次检查输入值。（注：本指令是不可用于ControlLogix处理器，但旧型号仍然可用。）