National Instruments NI 9144, User Manual

Page: 77 / 95

NI 9144 User Guide and Specifications
|
© National Instruments
|
77
unstrained measurement, which is analogous to the cold junction measurement of a
thermocouple measurement system. The strain equation is:
where V
r –st
and V
r –unst
are the strained and unstrained readings, respectively, from the module.
NI 9236
The vendor configuration extensions for the NI 9236 are listed in Table 81.
The NI 9236 is a DSA module and as such it does not synchronize with other modules but
free-runs at its own fixed rate.
Configure ADC
The NI 9236 (like the other DSA modules) can convert at various rates, controlled by the fields
in the ADC conversion command.
Table 81.
NI 9236 Vendor Configuration Extensions
Index Sub Type R/W Description
0x2002 0 U32 R/W Configure ADC,
default = 0xCE00
0x2100 0 ARR:U32 ... Calibration = 48
1 R Ch0 Offset
2 R Ch0 Gain
3 R Ch0 Shunt
4 R Ch1 Offset
... — —
24 R Ch7 Shunt
25 R External Ch0 Offset
... — —
strain e
( )
4
–
Vr st
–
Vr unst
–
–
( )
GF 1 2
+
( )
Vr st
–
Vr unst
–
–
( ) ⋅ [ ] ⋅
------------------------------------------------------------------------------------------ =