Cooper Instruments & Systems DFI 200 Hand Held Indicator User Manual
Page 10
CF 112
10
Version 3.1-0
Use of
and
as reference values.
Note: do not use this facility if an optional external memory chip is connected. If using the two point calibration
method (
and
) the mV/V value and scale is automatically calculated and stored at the
and
functions. After calibration using
and
the
and
values may be viewed and a
note taken of their value, ensure that you do not change either the
or
values whilst they are being
viewed. If the instrument is accidentally recalibrated incorrectly the
and
values recorded can be re-
entered to scale the instrument back to the same load cell. Note that the mV/V reference value stored at the
function will only match the manufacturers rated mV/V value for the load cell if
and
were
carried out at exactly 0% and 100% of rated load. For example if the manufacturer states that the load cell has a
2.000mV/V output and
and
were carried out at 0% and 50% of rated load then the
reference
value you would expect to see would be approximately half of the rated mV/V i.e. approximately 1.000 mV/V.
4.12 Calibration offset
Display:
Range: Any display value
Default Value: n/a
Allows the instrument calibration to be offset by a single point value. This value is added or subtracted across
equally the range of the instrument. This scaling method is used to correct for a constant error in the reading. The
procedure is as follows:
1. Press then release,
and
simultaneously to enter the
function. The display will show the
current display value.
2. Press the F button. The display will show
followed by the previous scale value.
3. Use the
or
button to alter this scale value to the required reading for the current input load.
4. Press F to accept the new scale value. The display will show
to indicate that the offset calibration
scaling has been completed.
4.13 Zero range limit
Display:
Range:
Default Value:
The zero range function is expressed as a percentage of full range (0.0 to 100.0%). The full range input is
calculated by the
figure minus the
figure for 2 point calibration or the
figure if
calibration is used. If the display value (as a percentage of range) is greater than the percentage selected in the
function then any attempt to zero the display will be aborted and a
message will be seen, the beeper will also sound repeatedly. If the zero operation is
successful then the instrument will beep once and the
message will be seen prior to the display value
going to zero.
A zero range setting of 0.0 will mean that no zero operation is possible, a zero range setting of 100.0 will mean that
the display can be zeroed at any time no matter what the display value at the time.
Example: A load cell is calibrated using 2 point calibration the
figure is 10 and the
figure is 70. If
the
function is set to 30.0 (30.0 percent) then the display can only be zeroed if the display is
below approximately 18. This is calculated by (
-
x 30%) i.e. (70 - 10) x 0.3 = 18.