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NOTE:
Set the scale back to the normal
weigh mode to insure that the
scale is reading zero with no
weight, and the correct span
value with the test weight.
NOTE:
You may prefer to use a digital
multimeter for this step rather
than reading the controller the
indicator is being used with.
As an example of this, we will calculate the coarse span value for a 0 to
10V output at 5000 lb. In this case, we will use the value of 15300 for
the 0 to 10V output and divide it by the full scale output of 5000.
15300/5000 = 3.06
This calculation gives us a coarse span value of 3.06. With this informa-
tion, we may now go and enter it into the indicator. At the "SPAN"
prompt, move down 1 level and you are ready to enter the calculated
value. Key in the calculated value in from the key board and press the
ENTER key. Move up 1 level to the "SPAN" prompt and horizontally
to the left back to the "ZERO" prompt.
Final zero and span calibration of the analog output
We are now ready to perform final calibration of the zero and span for
the analog output. The receiving device must be hooked up to the
indicator and in operation.
For the following final calibration steps, shift back into the Setup
Mode and remain in that mode during the final calibration process.
With the scale cleared of weight, check to see what the receiving device
is seeing at zero. If the receiving device is showing zero, you may
continue to the final span calibration. If the receiving device is showing
slightly behind zero, move down into the zero cal setting where you
keyed in the COARSE Zero value and enter a slightly larger number.
You may have to make several entries until you walk the receiving
device into zero. If you find the receiving device is seeing a slightly
above zero reading, enter a slightly smaller number and check the
receiving device again. Continue adjusting until the receiving device
reads zero. When completed, move back up to the "ZERO" prompt and
move horizontally to the right to the "SPAN" prompt.
You are now ready to perform the final span calibration. Enter the test
weight that you used to calibrate the scale back on the scale. You will
use this weight to calibrate the analog output as well. Remember that if
the test weight is only 50 percent of the full span value, the analog
output should be adjusted to only 50 percent of its span value. With the
test weight on the scale, check the receiving device for its received
value.
As with the zero adjustment, if the value is not what it should be, move
down into the span value and enter a slightly smaller or larger value as
is needed; "walk" the output in until the receiving device is indicating
the correct value for the amount of test weight on the scale.
When you have completed the final span procedure, run the weight up
and down on the scale to test zero and span output. When completed,
return the indicator back to the normal weighing mode.
Optional features
8-21
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