In This Guide
Normally must refer to a stated physical condition; it is not an unexplained synonym for fault-safe.
Define the reference state
Pepperl+Fuchs defines NO and NC through the state of an unactuated switch. Preserve the sensor's physical-reference definition when interpreting those labels. Primary reference: Pepperl+Fuchs output logic.
A normally closed label does not by itself describe every power-loss, broken-wire or internal-fault behavior. Keep normal target state and abnormal-condition interpretation in separate rows. The complete application architecture determines what the controller can actually distinguish.
A hypothetical state table
Imagine a fictional detection task with target absent, target present and power unavailable as three named conditions. An offer states NC for the defined normal sensing state but gives no power-unavailable interpretation. Populate the first relevant row from the actual documentation and leave the missing condition unresolved; do not fill it from the letters NC alone.
Make columns for physical condition, component output, receiver interpretation and evidence reference. This example identifies no HM safety function, circuit state or approved fault response. It does not instruct changing a contact logic in installed equipment.
Keep logic and diagnostics distinct
Ask which conditions the task must distinguish and which actual signals provide that information. A binary state can have several possible explanations if the architecture offers no additional diagnostic evidence.
Retain the agreed reference-state definition and complete fault interpretation with the input record. This guide helps a buyer read NO/NC terminology without asserting a universal safety category, promising detection of every fault or treating an output-state name as a complete description of the system's behavior during power interruption and abnormal conditions. Preserve the specified actuation condition beside each state.
Customer Questions
What does normally refer to?
The component's defined unactuated or reference physical state.
Does NC alone specify every power-loss behavior?
No. Retain the actual documented condition separately.
Does an NC label prove a complete safety function?
No. The complete architecture and applicable evidence determine that scope.
Primary References
These references support the technical principles discussed in this guide. The worked examples and review questions are educational.
Discuss Your Machine Requirement
Share your product, container, required output and the evidence needed for your technical review.
Request a Technical Review