Conair WSB - Manual (Page 74)

ERROR CORRECTIONS: RATE NUMBERS. (DATA line 2)
The RATE numbers are used by the software, each cycle, to calculate
material dispense times. They are adjusted every cycle until flow
rates stabilize. When a significant error is detected, the software
adjusts the RATE numbers.
The GRAM number is adjusted first. The TIME number (interrupts) is
changed only if either number falls above 32,768, or both fall below
16,384. In this event both GRAM and TIME numbers are doubled or halved
until the larger of the two is between 16,384 and 32,768.
In other words, both numbers are kept as large as possible (up to
32,768) allowing for the most accurate math, but not so large as to
overflow the registers.
Only the GRAM number changes from cycle to cycle, except under the
conditions noted above.
Check the GRAM number for a series of consecutive cycles. If it
remains unchanged, then the dispenses are accurate enough to not
trigger error corrections. Another possibility is that the parameters
(MI and NC) that determine when error corrections occur are somehow out
of range preventing corrections that should be occurring.
The PRC parameter limits adjustments to 10 percent. Do not expect any
single GRAM number change larger then 10 percent.
A gradual decrease in the GRAM number indicates a slowing rate, a
hopper that is becoming empty for example. A jump in rate (increased
GRAM number) occurs when the hopper is refilled.
If Errors are occurring, but the GRAM number is NOT adjusting, check
the NC parameter and the MI parameter. These control weather or not
error corrections occur. Both are set and adjusted automatically by
the software. MI is set after each start up, after 10 cycles have run
without retries. MI will be set to indicate 80 percent of normal
dispense rate expressed as grams per second.
NC adjusts slowly over extended periods of running. NC indicates, in
grams, the upper limit of the error in 60 percent of the dispenses. A
high number usually indicates poor flowing material. Vibration or
drifting load cells are other possibilities.
DISPENSE TIMING: (DATA line 3)
The second number is the number of interrupts calculated to dispense
the material. If these times are consistent but the weight of the
first dispense varies, then the material does not flow well, or
consistently. Another possibility is excessive vibration or
interference with the weigh bin.
Excess vibration, particularly on small dispenses, may cause incorrect
weight readings even though the weight dispensed was, in fact, correct.
If the timing number is very small, 10, 20, 30 interrupts, perhaps this
is asking too much from a slide valve. Very short times mean you want
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