Explain the Purpose and Functionality of the EXAMINE ON Instruction

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The Answer is Whenever the processor sees an N.O. contact in the user program, it views the contact symbol as a request to examine the address of the contact for an ON condition. If the N.O. contact has an input address, and if the real-world input device is closed, or ON, the processor sets the appropriate bit in the input register to 1, or ON. As the EXAMINE ON instruction is looking for an ON condition, a bit set to 1, or ON, is a true condition, and a logic path exists through the contacts. If the real-world input had been open, or OFF, the processor would have cleared the appropriate bit to 0, or OFF, and the contact would be false as far as the logic of the ladder diagram was concerned and would not allow a logic path.

Explain the Purpose and Functionality of the EXAMINE ON Instruction

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