National Instruments NI 9144, User Manual

Page: 74 / 95

74
|
ni.com
|
NI 9144 User Guide and Specifications
The calibration data is stored in a U32 array, though each Offset field (subindex 1, 3, 5, and so
on) should be interpreted as a signed value.
Use the calibration coefficients with the following equation to generate corrected data:
where V
raw
( bits ) represents data returned by the NI 9234 in bits
V
corrected
represents the corrected voltage value
NI 9235
The vendor configuration extensions for the NI 9235 are listed in Table 77.
The NI 9235 is a DSA module and as such does not synchronize with other modules but
free-runs at its own fixed rate.
Table 76.
NI 9234 Scan List Format
Coefficient Representation Units
LSB Weight Unsigned pV/LSB
Offset Signed nV
Table 77. NI 9235 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
... — —
Vcorrected Vraw
( )
Vraw bits
( )
LSBweight
pV
bits
----------
 
 
10
12
–
×
V
pV
-------
 
 
 
 
 
×
Offset pV
( )
10
9
–
×
V
nV
-------
 
 
– =
 
 
 
d