What does the instrument documentation actually say?
NI documents a specific behavior for PXIe-4081 waveform acquisition: an input outside the measurement range produces invalid NaN values, and recovery can include further invalid points. Its warning is therefore part of the evidence, not a numerical measurement of how far the signal went beyond the range.
Commissioning Docs is independent and is not affiliated with NI. Other instruments and export formats can behave differently. Read the actual model, function and software documentation rather than apply this example to every meter or historian.
Sources: NI: NI PXIe-4081 documentation: Acquiring Current and Voltage Waveforms, checked 20 October 2026
Which states should the result register keep separate?
Keep the original export and its status fields. If a spreadsheet cannot represent the instrument status, retain a separate linked status column instead of replacing invalid data with a convenient number.
| Result state | Evidence to keep | Review disposition |
|---|---|---|
| Valid reading | Value, unit, time and status | Assess against the approved criterion |
| Overrange warning | Exact warning and channel | Peak remains unresolved |
| Invalid sample | Original marker and export definition | Do not substitute zero |
| Recovery interval | Actual instrument guidance and data | Do not invent a universal duration |
| Reacquisition | Approved new test and result reference | Keep the original exception |
| Acceptance | Authorized technical decision | No automatic pass or fail from a blank |
How can a summary conceal the problem?
Illustrative example. A fictional export contains valid values of 8 and 9 signal units, with an invalid overrange entry between them. A spreadsheet replaces the invalid entry with zero and reports 9 as the maximum for the entire interval. Nine is the largest retained valid number; the evidence does not establish the true peak during the invalid interval.
The reviewer retains all three original states, labels the interval incomplete and asks the commissioning lead for an approved disposition. A larger graph axis, interpolation or copied neighbor value does not recover the missing measurement. The example provides no equipment limit or real measured result.
What should happen before the record is closed?
Identify which requirement needs a valid peak, how the warning affects that requirement and who can approve further work. Any repeat measurement needs an approved method, appropriately selected equipment and the site safety process. Do not change ranges on energized equipment from a generic web instruction.
This is an evidence-control worksheet, not an instrument selection or test procedure. Engineering sign-off is performed only by the registered engineer on the job.
Common questions
What else should the bid team know?
Is an invalid overrange entry a measured zero?
No. Preserve its actual status and meaning.
Can the true peak be reconstructed from the range label alone?
No. The label is not the missing waveform.
Does this article prescribe a recovery time?
No. Obtain the actual instrument guidance and technical disposition.