Omega LDX-4 User Manual page 12

5.2: Basic Procedure
STEP 3 - Setting Bi-Polar Full-scale Output
1. Move the transducer to the position where maximum LDX-4 output is required.
2. If the polarity of the output is wrong, move the Polarity (FR) links to the R posi-
tion (see link diagram).
3. Move the RANGE link between 1 and 6 until the LDX-4 output is near the
required value.
4. Adjust the Fine Gain control to give the required output.
5. A bi-polar output has now been set, proceed to step 5. If a uni-polar output is
required, proceed to step 4.
Example: ±10 VDC is required from a ±1 mm transducer. Set the transducer to +1
mm and set the output to 10 V.
If your transducer is known to be outside of the standard sensitivity range, the X2,
X4 or DIV2 links will have to be used. See section 5.3.
STEP 4 - Setting Uni-polar Full-Scale Output (adding an offset)
1. Move the transducer to the null position. LDX-4 output will be 0 V or 0 mA.
2. Apply offset using the +VE, -VE, 5 V and 10 V links and then adjust the Fine
Offset control to set the offset precisely.
3. Perform final checks, step 5.
Example: 0-10 V is required for a ±1 mm transducer. Set the transducer to give ±5
V over the full range and then, with the transducer at null, add +5 V offset. Adjust
the Fine Offset control to give 5 V. When the transducer is moved to the
+1 mm position, the output will be +10 V.
Example: 4-20 mA is required for a ±1 mm transducer. Set the transducer to give
±8 mA over the full range and then, with the transducer at null, add +2.5 V (approx.
5 mA) offset. Adjust the Fine Offset control to give +12 mA. When the transducer is
moved to the +1 mm position, the output will be +20 mA.
STEP 5 - Final Checks
Ensure that the calibration is correct by moving the transducer across the required
mechanical range, checking calibration points. Fine adjustment can be made if
required.
It may only be possible to set the output accurately at the two calibration points.
This is due to non-linearity within the transducer.
5.3: Transducer Sensitivity and the X2, X4, DIV2 Link
The LDX-4 compensates for changes in primary signal amplitude by producing an
internal error signal that is the ratio between the primary and secondary signals. If
the transducer output signal is too high or too low, errors may occur that can de-
grade the performance of the LDX-4 / transducer combination. For these transduc-
ers, the X2, X4 or DIV2 input gain link must be used.