An indicator converts millivolts into kilograms using two numbers: a zero offset and a span. Getting them right in the right order is the whole job, and most commissioning errors come from doing it in the wrong order.
Sequence
Mechanically zero the system with the dead load in place, then set the indicator zero. Apply a test weight of at least 20% of capacity, ideally close to the working load, and set the span. Remove and reapply the weight to check repeatability, then check zero again. If the indicator offers multi-point linearity, do it last, using three or more weights spread across the range.
Why order matters
Linearity correction modifies the curve between calibration points. If span changes afterwards, the correction no longer fits and the intermediate points go wrong. The same applies to corner adjustment on multi-cell platforms: adjust corners first, then span, then linearity.
Documentation
Record the raw mV/V at zero and at the test weight, the indicator counts, the weight used and its certificate number, and the ambient temperature. When the system drifts six months later, those numbers tell you whether the cell or the indicator moved.
Kevin Huang