Conair GB - Manual (Page 66)

CALIBRATION routine, or simply allowed to adjust automatically as
necessary after each cycle.
_WT and _TI are WEIGHT and TIME numbers that, taken together,
indicate a dispense rate for the specified material (WT/TI). This rate
is used to calculate an exact time period to dispense the required
quantity of material. Both of these numbers are adjusted by the
computer logic after each cycle as a means of continuously calibrating
the dispense times.
Since rate correction takes place continuously and the battery-
backed RAM maintains the correct rate even when power has been turned
off, these numbers will only be in error during the first several
cycles after a flow rate has been considerably altered.
Should there be a change in auger size, drive motor RPM, or some
other change that substantially alters the feed rate of one of the
components, the _WT and _TI parameters can be adjusted using the RATE
CALIBRATION routine to ensure that the feeders dispense properly right
from the beginning without waiting for adjustments to occur.
These numbers are always kept at higher values. The computer will bump
both numbers up in value by doubling them both until at least one
number exceeds 16,000. The ratio (rate) is still the same but error
correction routines work better with higher numbers.
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_MI (Set AUTOMATICALLY by the CALIBRATE routine and also reset
10 cycles after every power up)
_MI numbers are set to 80 percent of the amount of material, in
grams, that can feed in one second based on normal valid dispense
rates. A valid rate is considered the normal dispense rate that occurs
under normal conditions with equipment functioning properly. When a
rate lower than 80 percent of this actually occurs, it is assumed that
an equipment malfunction or loss of material has occurred. Under these
circumstances, normal rate correction routines are bypassed.
EXAMPLE: For a 1/2" auger feeder with a 60 RPM motor drive, the
normal metering rate is about one gram per revolution or 1 gram
per second. Since the _MI number is expressed as tenths of grams,
80 % of this is expressed as:
(_MI 00008)
It is safe to use a _MI number that is too low but NOT safe to use
a number too high. Error correction routines will not work when
this number is too high.
Power-up always resets _MI to 00001. After 10 cycles have
occurred without retries, software will enter a corrected number. An
exception to this is when the _AL (Alarm) parameter is set to 0, the MI
parameter is left unchanged. RATE CALIBRATION also sets the _MI
parameter.
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_NC (Changes itself automatically over time)
_NC is the allowable GRAM error within which NO flow rate
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