Field Pocket Guide

Calibration Error

Apply your standard, record the output. The worksheet returns error as percent of span, not percent of reading, with the sign handled for you. You only ever key in the magnitude you read.

Loop setup

Define the input you apply and the output you measure. Use the ± toggle for compound or below-zero ranges.

Worksheet

Enter the applied input you actually put in and the worksheet computes that row's expected output, then grades the As-Found (before adjustment) and As-Left (after) readings. The point buttons seed the set points; your tolerance caps how far an applied input can stray from its set point, so a reading can't be hidden by fudging the input. Stray past it and the value snaps back to the band edge.

Applied input % Expected As-Found Found err As-Left Left err

Expected output = your applied input mapped across the ranges, held at the output limits so it never runs past the origin or full scale (marked sat). Error = (measured − expected) ÷ output span × 100. A negative result reads low.


As-Found · max error
% span
As-Left · max error
% span
Verdict
Enter readings
Percent of span, by design. Span error treats a 0.1 mA miss the same at 4 mA and at 20 mA, which is how a loop is judged. Percent of reading would flatter the high end and punish the low end. Set your tolerance once; every point is graded against it.