Measurement Technology NW
LCI-90 Operator Manual
Page 36
5.9
Payout Calibration
To set the Payout calibration, push
CALB
to display the main
2.0 CALIBRATION
menu
shown below. In this example the units shown are in feet. To change to other units see Sec-
tion 5.6.2. Items 5 and 6 allow the operator to set the scale factor (pulses per foot) and the
preset value. These two settings are explained in Section 5.9.1-2.
2.0 CALIBRATION
1
TENSION (THREE METHODS)
2
TENSION TARE
OFF
3
SHUNT CAL
OFF
4
WRAP ANGLE
120 DEG
>
5
PAYOUT SCALE
2.800 P/FT
6
PAYOUT PRESET
150 FT
5.9.1 Payout Scale
The payout scale factor represents the number of pulses per unit length. In a typical
application the line will pay out over a sheave with a known circumference and
number of targets (= pulses) per revolution. The payout scale factor is calculated as
follows:
Payout Scale = Number of Targets / Sheave Circumference
The LCI-90 expects to receive pulses generated by a pair of offset sensors that see the
targets in sequence (or quadruture pulses generated by a shaft encoder). The quadra-
ture signal allows the count to increment or decrement depending on the direction of
motion. The quadrature outputs of the two sensors (called A and B) look like two
superimposed square waves that are 90 degrees out-of-phase (i.e. partially over-
lapped). A single pulse in terms of the scale factor consists of the two rising and the
two falling edges of waves A and B. For encoder signals, the LCI-90 also counts the
two rising and two falling edges as one pulse.
5.9.2 Payout Preset
Selecting Item 6, Payout Preset value, allows the operator to manually enter a Payout
value. This value is entered as a length in the current Payout units, but is saved by
the LCI-90 as a scaled number of counts. If the scale value is subsequently changed,
the saved value is adjusted to preserve the specified Preset.
