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NI 9144 User Guide and Specifications
Table 45 contains the default scan list.
NI 9217 Calibration Data
The NI 9217 has four RTD channels that can measure 100
Ω
RTD in 3-wire and 4-wire mode.
There is a 1 mA excitation current source per channel and the module range is -500 to 500
Ω
.
The resistance range specified in the manual is 0 to 400
Ω
. This range is tested and covers the
temperature range of -200 to 850 ºC for the standard platinum RTD. The channel does not read
negative resistance.
Each channel has an associated LSB weight, which is the number of ohms per bit, and an offset,
which is the number of ohms per bit measured when the inputs are grounded.
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 correct data:
where
R
raw
(
bits
) represents data returned by the NI 9217 in bits
R
corrected
represents calibrated resistance reading
Table 45.
NI 9217 Scan List Format
Index
Sub
Type
Value
0x2001
0
ARR:U32
5
1
4
2
0x0000 | 0xF8 | 0x02
3
0x0100 | 0xF8 | 0x04
4
0x0200 | 0xF8 | 0x06
5
0x0300 | 0xF8 | 0x00
Table 46.
NI 9217 Calibration Coefficients
Coefficient
Representation
Units
LSB Weight
Unsigned
p
Ω/
LSB
Offset
Signed
mW
Rcorrected Rraw
(
)
Rraw bits
(
)
LSBweight
p
Ω
bits
----------
10
12
–
×
Ω
p
Ω
--------
×
Offset
μΩ
(
)
10
6
–
×
Ω
μΩ
--------
–
=