From the course: Learning PLC Ladder Logic: 1 The Basics

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Input instructions

Input instructions - Ladder Logic Tutorial

From the course: Learning PLC Ladder Logic: 1 The Basics

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Input instructions

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- [Instructor] Let's take a look at what input means in PLC ladder logic programming. The way we write input is as following: as two bars facing each other representing the input. And to differentiate between the physical input device and the input within the software, we will refer to the input in the PLC program as input instruction. There are two main types of input instructions; Examine If Closed, XIC, and sometimes called normally open, Examine If Open, XIO, and sometimes it's called normally closed. Notice, that the only difference between them, is that the XIO has a sidebar that indicates it's already closed and we're examining if it opens. In ladder logic program, the instruction is highlighted when the logic state is true. I'll be using a green highlight in the slides here, similar to what is used in Allan-Bradley software. However, it's very similar in any other PLC types. Different colors might be used in different softwares but they all indicate the same concept. Examine…

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