National Instruments FP-3000 - Manual (Page 44)

Chapter 3 Example Applications
© National Instruments Corporation 3-9 FieldPoint FP-3000 User Manual
Set the Input Range and Thermocouple Type
1. Click on the FP_TC_120_RANGE parameter on the I/O Config tab in
the block configuration window. This parameter tells the AI block the
range of values it should expect from the FP-TC-120 module.
2. Set the parameter to 0–2048K (degrees Kelvin).
3. Set the FP_THERMOCOUPLE_TYPE to the type of thermocouple you
have connected (such as J or K type thermocouple). This allows the
FP-TC-120 module to perform the necessary calculations on-board to
convert the electrical input from your thermocouple to the 0-2048
degrees Kelvin that it will send to the AI block.
Tip The Kelvin scale covers more than all possible temperature you could measure.
It corresponds to –273.15 °C to 1775 °C.
Scale the Reading
1. You can avoid setting the XD_SCALE value manually if you set the
CFG_OPTS option on the Options tab to Automatically Adjust
XD_SCALE . This allows the FP-3000 to copy the value from
FP_TC_120_RANGE straight into the XD_SCALE parameter. Otherwise,
tell the block the range of values to expect from the transducer. Go to
the
XD_SCALE parameter on the Scaling tab and enter the following:
XD_SCALE
EU_100 2048
EU_0 0
Units_Index K
Decimal 2
This tells the AI block to expect readings in the range of 0 to 2048 K
from the thermocouple module.
2. Determine the output scale. If you want to output the temperature in
degrees Kelvin, you can set
OUT_SCALE to the same values as
XD_SCALE above. If you want to change to Celsius, you can do so by
setting OUT_SCALE as follows:
OUT_SCALE
EU_100 1775.00
EU_0 -273.15
Units_Index °C
Decimal 2
These temperatures correspond to the Kelvin range you specified for
the
XD_SCALE .