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Method 2 – Determining calibration scale factors by experiment
Calibrating a system with an unknown number of sensor targets or gearbox ratio:
1.
Verify that the mechanism and sensors (or sensor if only 1 input is being used, and it is
not necessary to use quadrature) are operating correctly.
2.
Determine if 1 (Single input) or 2 (Quadrature) sensors will be used.
3.
Determine the display precision required (number of decimal places).
4.
Connect the system to a PC as described in the section on the
Command Console
Interface
on page 27. Set both the numerator and denominator to 1 using the Console
interface commands:
PNUM+0001.
PDEN0001
This makes the overall scale factor 1.
5.
Check the display is reading 0. Zero the display if not.
6.
Operate the system over a set number of complete turns or known number of unit lengths
for distance, whichever is appropriate to the application.
Ensure the direction of travel is that intended to be used for a positive count
when using a quadrature system.
Ensure the start and finish points are precisely marked and aligned both before and after
to ensure the calibration procedure is accurate.
For example, with a torque tool, mark both the outer body and the drive socket as aligned
with the display reading 0 and ensure the tool is stopped at precisely the same point.
10 is a reasonable number of turns for a torque tool, but more turns will give a more
accurate calibration, particularly if the tool is intended to be used over many hundreds of
turns.
7.
Record the displayed value (the unscaled count). (This may also be read from the console
interface if still connected).
8.
The numerator is the number of turns executed or the number of unit lengths. The
denominator is the unscaled count.
Numerator
= Number of turns / units lengths
Denominator
= unscaled count
9.
Format Numerator (add sign, decimal point and leading zeros as required) and
Denominator (add leading zeros as required).
10.
Connect the system to a PC as described in the section on the Command Console
Interface on page 27. Enter the numerator and denominator using the commands:
PNUM??????
PDEN????
11.
Check the calibration using the
Calibration Check Procedure
on page 15.
See the next page for an example.