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National Instruments Corporation
51
NI 9144 User Guide and Specifications
NI 9233 Calibration Data
The NI 9233 has four input channels with a fixed gain. The inputs are
AC-coupled so calibration is done with a sine wave rather than with DC
signals. The specification derivations are based on calibration at 250 Hz,
acquired at 25 kS/s. The AC response (flatness) changes with both input
frequency and sample rate; therefore, calibrating at different signal
frequencies or at different sample rates gives different results.
Each channel has an associated LSB weight, which is the number of volts
per bit, and an offset.
Note
LSB weight is referred to as Gain in the object dictionary.
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:
10.000 kS/s
1
00101
10
0x96
2.56 MHz
6.250 kS/s
1
01000
10
0xA2
1.60 MHz
5.000 kS/s
1
01010
10
0xAA
1.28 MHz
3.333 kS/s
1
01111
10
0xBE
853 kHz
3.125 kS/s
1
10000
10
0xC2
800 kHz
2.500 kS/s
1
10100
10
0xD2
640 kHz
2.000 kS/s
1
11001
10
0xE6
512 kHz
Table 45.
NI 9233 Scan List Format
Coefficient
Representation
Units
Default Value
LSB Weight
Unsigned
pV/LSB
0x0009D292
(643.73 nV/bit)
Offset
Signed
nV
0x00000000
(0 nV)
Table 44.
NI 9233 Calibration Data (Continued)
Data Rate
Turbo
Disable
Clock
Divisor
Clock
Source
Configure
ADC
Oversample
Clock Rate
Calibrated_Data =Binary_Data LSB_Weight
×
Offset
–
