Campbell Scientific CR3000 Micrologger - Manual (Page 306)

Section 8. Operation
306
Table 66. StrainCalc() Instruction Equations
StrainCalc()
BrConfig Code Configuration
3
Half-bridge strain gage. One gage parallel to + , the other parallel to -
:
4
Full-bridge strain gage. Two gages parallel to + , the other two parallel
to - :
5
Full-bridge strain gage. Half the bridge has two gages parallel to + and
- , and the other half to +
and - :
6
Full-bridge strain gage. Half the bridge has two gages parallel to + and
-
, and the other half to - and + :
where:
• : Poisson's Ratio (0 if not applicable)
• GF: Gage Factor
• V
r
: 0.001 (Source-Zero) if BRConfig code is positive (+)
• V
r
: -0.001 (Source-Zero) if BRConfig code is negative (-)
and where:
• "source": the result of the full-Wheatstone-bridge measurement (X = 1000 *
V
1
/ V
x
) when multiplier = 1 and offset = 0.
• "zero": gage offset to establish an arbitrary zero (see FieldCalStrain() in
FieldCal() Demonstration Programs
(p. 158)
).
StrainCalc Example: See FieldCalStrain() Demonstration Program
(p. 167)
8.1.4 Thermocouple
Note Thermocouples are easy to use with the CR3000. They are also
inexpensive. However, they pose several challenges to the acquisition of accurate
temperature data, particularly when using external reference junctions. Campbell