From the course: PLC Program Flow and Control Instructions

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First in, first out (FIFO) instruction

First in, first out (FIFO) instruction - Ladder Logic Tutorial

From the course: PLC Program Flow and Control Instructions

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First in, first out (FIFO) instruction

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- [Narrator] There are two instructions for FIFO function. The first one is called First In First Out Load and the second one is, First In First Out Unload. The two instructions are used in pairs. The load instruction is used to load words into a user created file called a FIFO Stack, the unload instruction is used to unload the words from the FIFO file in the same order as the words were entered as you can see, the two instructions are Block Type Instructions. The name on the top is to specify whether it's a load or unload instruction. The FIFO instructions are output instructions. So there are placed on the right hand side of the ladder logic. The load and the unload happens on every false to true transition of the instruction. You can find the two instructions under the tab, file, shift, slash sequencer and you can see the first two are for FIFO. And the last two are for LIFO. One example of using Word Shifting…

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