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XIO — Examine If Open

dataBit

/

Passes power along the rung when the referenced bit is 0. Equivalent to a normally-closed contact and the closest thing to a NOT in ladder logic.

Operands​

NameType
dataBitBOOL

How It Works​

If dataBit is 0, power passes through. If 1, power is blocked.

Example​

XIO(Fault)OTE(Ready)

Ready is energized while Fault is 0.

Looking for NOT?​

Ladder Logic has no dedicated NOT instruction. XIO is the NOT — it passes power when the bit is off.

Common Mistakes​

  • Expecting a NOT or ! symbol — use XIO instead.