KERN CXB 30K2 Mode D'emploi page 82

8.2 Numeric entering of the reference weight
If you know the reference weight/piece you can enter this via number keys.
Enter reference weight via number keys
Confirm with button
Now you can place the parts to be counted onto the weighing plate. All quantity
parameters of your goods to be weighed are displayed:
8.3 Automatic reference optimization
If it was impossible to determine a reference due to instable goods to be weighed or
an insufficient reference weight, the [ ] display will appear in the reference weight
window during reference calculation.
Overlay  indicates:
Placed number of pieces insufficient for reference calculation
< 40 d
Placed reference weight insufficient for reference calculation
< 4/5 d
Add additional parts until the [ ] display disappears.
An audio signal indicates that reference optimization has been carried out.
At every reference optimisation, the reference weight is calculated anew. As the
additional pieces increase the base for the calculation, the reference also becomes
more exact.
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Reference weight
CXB-BA-e-2124