National Instruments Deterministic Ethernet Expansion Chassis NI 9144 - Manual (Page 35)

© National Instruments Corporation 35 NI 9144 User Guide and Specifications
NI 9215 Calibration Data
The NI 9215 has four channels with a nominal range of ±10.4 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 9215 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:
NI 9217
Table 25. NI 9215 Calibration Coefficients
Coefficient Representation Units
LSB Weight Unsigned nV/LSB
Offset Signed nV
Table 26. NI 9217 Vendor Configuration Extensions
Index Sub Type R/W Description
0x2001 0 ARR:U32 — Scan List = 5
1 R Channels to Convert = 1..4,
default = 4
2..5 R/W Channel Code
0x2002 0 U32 R/W Conversion Speed Control = 2 or 31,
default = 31
V
corrected
V
raw
( ) V
raw
bits ( )∗ LSB
weight
nV
bits
---------
⎝ ⎠
⎛ ⎞∗10 9 –
V
nV
-------
⎝ ⎠
⎛ ⎞
⎩ ⎭
⎨ ⎬
⎧ ⎫
Offset nV ( )∗10 9 –
V
nV
-------
⎝ ⎠
⎛ ⎞
⎭
⎬
⎫
– =