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

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Normally closed (NC) contact with XIC and XIO

Normally closed (NC) contact with XIC and XIO - Ladder Logic Tutorial

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

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Normally closed (NC) contact with XIC and XIO

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- [Narrator] Now, we'll take the same previous example but use a normally closed contact instead. So using a normally closed relay and having two different instructions in the PLC program. Examine if closed. Examine if open. A normally closed contact is normally closed and it provides the electrical continuity. It opens when the contact is pressed. The physical contact is open. Now, we're using a normally closed pushbutton that is connected to an input module in PLC. And a red light connected to the output module in PLC. For a normally closed contact pushbutton, if the pushbutton is not pressed, the memory location connected to that pushbutton within the module is showing one. As soon as the pushbutton is pressed, the continuity changes and then the memory address changes its state to zero. There is no physical continuity. Now let's see what happens in the program when using two different instructions. Using XIC, remember XIC instruction is activated when the memory location is one…

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