Measurement Computing LogBook Series - Manual (Page 146)

LV-20 LogView 989592 Software Reference
User Scaling. Final Reading = Scale*RawReading + Offset
An Example of Using LogView for 2-Point Calibration
Once the trimpots have been physically adjusted during initial installation, periodic trimming can be
performed through LogView’s 2-Point software calibration. The LogView procedure does not require the
use of trimpots and should not be confused with the 2-point method in which trimpots are mechanically
calibrated as discussed in the DBK16 section of the DBK Option Cards and Modules User’s Manual.
During the LogView software procedure, 1 or 2 loads are read and compared with expected values. The
software automatically calculates and applies the necessary correction factors.
The above figure shows the columns in the 2-Point Calibration tab. To fine tune the accuracy of the
value coming from a linear sensor, LogView provides both 1- and 2-point calibration.
• One-point calibration can be used to zero a channel, such as a thermocouple channel, which is
usually more accurate in scale than offset. One example of one-point calibration is that of placing a
thermocouple in an ice bath and setting the 0°C point, and no other.
• 2-point calibration determines the scale and offset factors to convert the raw readings into accurate
calibrated readings. Two points of known (set) values must be compared with two actual sensor
readings.
An example of 2-Point Calibration (via LogView Software).
To calibrate a strain-gage scale:
1. Unload the scale.
2. Enter a value of 0.0 into the Set P1 column.
3. Click
the Get P1 button. This lets you read the actual sensor value (2.0 in the
example).
4. Place a 100 lb. weight on the scale.
5. Enter a value of 100 into the Set P2 column.
6. Click the Get P2 button. This lets you read the actual sensor value (95.0 in
the example).