Rice Lake Legend 480-2A, Technical Manual

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68 480 Legend Series
9.10 Conversion Factors for Secondary Units
The 480 has the capability to mathematically convert a weight into many different types of units and instantly
display those results with a press of the
Unit
key.
Secondary units can be specified on the Format menu using the
SECNDR
parameter.
Multipliers are preconfigured within the indicator.
Ensure that the secondary decimal point position is set appropriately for the scale capacity in the secondary
units. If the converted value requires more digits than are available, the indicator will display an overflow
message (OVERFL).
For example, if the primary units are short tons, secondary units are pounds, and the secondary decimal point is set to
8888.88, the indicator will overflow if five tons or more are applied to the scale. With 5 tons applied, and a conversion
factor of 2,000, the secondary units display needs five digits to the left of the decimal point to display the 10,000 pound
secondary units value.
9.11 Digital Filtering (DIGFIL)
Digital filtering is used to create a stable scale reading in challenging environments. The 480 (firmware version
1.03 and later) allows selection of
Adaptive Filtering
(see Section 9.11.2),
Rolling Filtering
(see Section 9.11.3) or
OFF
for no filtering.
The A/D sample rate must be selected first (see Section 9.11.1). Then select the type of digital filter using the
DIGFIL
parameter.
9.11.1 Sample Rate (SMPRAT)
The A/D sample rate is the number of weight readings the indicator takes per second (
SMPRAT
). This can be 5, 10,
20 or 40 Hertz, or readings per second.
Set the A/D sample rate to the lowest setting required for the application. Lower settings result in better stability, so
5 Hertz is more stable than 40 Hertz.
9.11.2 Adaptive Filter
The adaptive filter has two settings, sensitivity (
AFSENS
) and threshold (
AFTHRH
). It maintains a running average
of the A/D readings when the weight change remains less than the defined Threshold value. The filter
automatically applies less value to each successive A/D reading the longer the weight change is less than the
Threshold value. The amount of value given to the most recent A/D reading is determined by the sensitivity setting.
Adaptive Filter Sensitivity (AFSENS)
Adaptive filter sensitivity (
AFSENS
) can be set to
HEAVY
,
MEDIUM
or
LIGHT
. A heavy setting will result in an output
that is more stable to weight changes, than that of light. However, small changes in weight data (a few grads) on the
scale base will not be seen as quickly.
If the difference in typical subsequent weight values on the scale will only be a few grads, use a light setting. On a
truck scale where the changes in subsequent weight values will be 100s of grads, a heavy setting will be more
appropriate. When the weight has not exceeded the Threshold (
AFTHRH
) setting, the effective response is
approximately 30 A/D cycles for
LIGHT
, 90 A/D cycles for
MEDIUM
and 180 A/D cycles for
HEAVY
.
Adaptive Filter Threshold (AFTHRH)
The adaptive filtering threshold (
AFTHRH
) should be set for the amount of observed instability in the system. This
parameter can be set in the range of 0 to 99999 and is entered as a weight value. When a new sampled weight value
is acquired, the adaptive filter compares the new value to the previous (filtered) output value.
If the difference between the new value and the previous output value is greater than the
AFTHRH
parameter the
adaptive filter is reset to the new weight value.
If the difference between the new value and the previous output value is less than the
AFTHRH
parameter, the two
values are averaged together using a weighted average. The weighted average is based on the amount of time the
system has been stable, and selected
AFSENS
sensitivity.
With the adaptive filter threshold set at zero, determine the amount of instability that is present. Enter this amount
of weight instability to set the threshold of the adaptive filter. The adaptive filter is set to
OFF
the
AFTHRH
parameter is set to zero.
Note