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NI 9144 User Guide and Specifications
NI 9220
The vendor configuration extensions for the NI 9220 are listed in Table 61.
NI 9220 Calibration Data
The NI 9220 has 16 channels with a nominal range of ±10.5 V. Each channel has an associated
LSB weight, which is the number of volts per bit, and an offset, which is the number of volts per
bit measured when the inputs are grounded.
Note
LSB weight is referred to as Gain in the object dictionary.
The NI 9220 EEPROM stores these two constants for each channel. The host can then take these
constants and adjust the raw data into calibrated data.
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 raw data returned by the NI 9220
V
corrected
represents the corrected voltage value
Table 61.
NI 9220 Vendor Configuration Extensions
Index
Sub
Type
R/W
Description
0x2100
0
ARR:U32
—
Calibration = 64
1
R
Ch0 Offset
2
R
Ch0 Gain
3
R
Ch1 Offset
...
—
—
32
R
Ch16 Gain
33
R
User Calibration Ch0
Offset
...
—
—
Table 62.
NI 9220 Calibration Data
Coefficient
Representation
Units
LSB Weight
Unsigned
pV/LSB
Offset
Signed
nV
Vcorrected Vraw
(
)
Vraw bits
(
)
LSB
weight
pV
bits
---------
10
12
–
×
V
pV
-------
×
Offset
n
V
(
)
10
9
–
V
nV
-------
×
–
=
