Normally closed contact symbol
Also called NC contact, XIO, Examine if open
Passes power when its bit is 0 (false). In Allen-Bradley PLCs it is the XIO instruction, examine if open.
IEC 61131-3What the normally closed contact symbol means
Passes power when its bit is 0 (false). In Allen-Bradley PLCs it is the XIO instruction, examine if open.
How it is drawn
IEC 61131-3 ladder diagram
Normally closed contact. Two vertical lines with a diagonal slash between them.
LD SVGWhere you see it
Conditions that must be off: a fault not present, a stop or interlock not active, a step not yet done.
Related symbols
Frequently asked questions
What does the normally closed contact symbol look like?
Two vertical lines with a diagonal slash between them.
Where is a normally closed contact used?
Conditions that must be off: a fault not present, a stop or interlock not active, a step not yet done.
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