Rice Lake IQ Plus 355 Installation Manual V1.17 - Manual (Page 30)

26 IQ plus 355 Installation Manual
4.4 More About Calibration
The following topics provide additional information
about compensating for environmental factors
(Section 4.4.1) and diagnostic information for
determining expected zero and span coefficients.
4.4.1 Adjusting Final Calibration
Calibration may be affected by environmental factors
including wind, vibration, and angular loading. For
example, if the scale is calibrated with 1000 lb, a
strain test may determine that at 2000 lb the
calibration is 3 lb high. In this case, final calibration
can be adjusted by tweaking WVAL to 998.5 lb. This
adjustment provides a linear correction of 1.5 lb per
1000 lb.
To adjust the final calibration, return to the
WVAL
prompt and press to show the test weight value.
Press or to adjust calibration up or down. Press
to save the value, then press to return to the
CALIBR menu.
4.4.2 Zero Deadload A/D Counts
Table 4-1 lists the ideal A/D counts that result from
input signals of 0–45 mV with zero deadload. Actual
values will typically be higher than the values shown
in Table 4-1 but the ideal values can be used when
calibrating the indicator with no attached scale.
4.4.3 Calculating the Span Coefficient
The span coefficient value displayed by the WSPAN
parameter can be calculated using the following
formula:
(21000 * mV_signal_input) + zero_coefficient
where mV_signal_input is the change in the signal
input when the test weight is applied and the
zero_coefficient is the WZERO value. Actual values
typically vary from the calculated value.
Input Signal (mV) Raw A/D Count
0 105 000
1 126 000
2 147 000
3 168 000
4 189 000
5 210 000
6 231 000
7 252 000
8 273 000
9 294 000
10 315 000
15 420 000
20 525 000
30 735 000
45 1 050 000
Table 4-1. Ideal A/D Raw Counts