Campbell CR9000, Инструкция по эксплуатации

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Section 8. Processing and Math Instructions
8-21
Parameter
& Data Type
Enter
StrainCalc Parameters
Dest Variable to store strain in.
Reps Number of strains to calculate, Destination, source, and zero variables must be dimensioned
accordingly.
BrConfig Bridge configuration code for strain gages The bridge configuration code can be entered as a
positive or negative number:
+ code:
V
r
= −
0 001 . ( ) Source Zero
; bridge configured so its output decreases with
increasing strain.
- code:
V
r
= − −
0 001 . ( ) Source Zero
; bridge configured so output increases with strain.
This is the configuration for a quarter bridge using CSI’s 4WFB350 Terminal Input Module
(i.e., enter the bridge configuration code as -1 for 1/4 bridge with TIM.)
Code Configuration
1
Quarter bridge strain gauge
µε =
− ⋅
+
4 10
1 2
6
V
GF V
r
r
( )
2
Half bridge strain gauge, one gage parallel to strain, the other at 90
°
to strain:
µε
ν ν
=
− ⋅
+ − −
4 10
1 2 1
6
V
GF V
r
r
[( ) ( )]
3 Half bridge strain gauge, one gage parallel to
+ε
, the other parallel to
−ε
:
µε =
− ⋅
2 10
6
V
GF
r
4 Full bridge strain gage, 2 gages parallel to
+ε
, the other 2 parallel to
−ε
:
µε =
−
10
6
V
GF
r
5 Full bridge strain gage, half the bridge has 2 gages parallel to
+ε
and
−ε
: the other
half
+νε
and
−νε
:
µε
ν
=
− ⋅
+
2 10
1
6
V
GF
r
( )
6
Full bridge strain gage, one half
+ε
and
−νε
, the other half
−νε
and
+ε
.:
µε
ν ν
=
− ⋅
+ − −
2 10
1 1
6
V
GF V
r
r
[( ) ( )]
Source The source variable array for the measurement(s), the input is expected as millivolts out per
volt in (the result of the full bridge instruction with a multiplier of 1 and an offset of 0.
Zero The variable array that holds the unstrained reading(s) in millivolts out per volt in.
GF Gage Factor. The gage factor can be entered as a constant used for all repetitions or a variable
array can be loaded with individual gage factors which are automatically used with each rep.
To use an array enter the parameter as
arrayname (), with no element number in the
parentheses.
v
Poisson ratio, enter 0 if it does not apply to configuration.
StrainCalc Example
This example uses StrainCalc to find the microstrain value of a bridge output.