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NI 9144 User Guide and Specifications
4.
Use the above final coefficients and complete the following steps in the quadratic equation
to convert raw 16-bit data into scaled volts.
where f64(
x)
typecasts the value to a floating point:
a.
a
0
= (f64(a
0
) × rangeGain) + rangeOffset
b.
a
1
= f64(a
1
) × rangeGain
c.
a
2
= f64(a
2
) × rangeGain
d.
a
3
= f64(a
3
) × rangeGain
5.
Use the following formula with a
3
-a
0
to obtain the scaled 16-bit value in volts.
where
x
is signed un-scaled raw 16-bit data read from a device:
Scaled 16-bit signed data in volts = a
3
×
x
3
+ a
2
×
x
2
+ a
1
×
x
+ a
0
You can decode the raw data using only the offset and gain values. For more information, refer
to the
NI 9201/9221
section of this guide.
Note
The offset and gain values of the NI 9205/9206 are different from those of the
NI 9201/9221. Use 10E
-9
for the offset value and 10E
-12
for the gain value if you
apply the linear equation of the NI 9201/9221 for the NI 9205/9206.
NI 9207
The vendor configuration extensions for the NI 9207 are listed in Table 18.
NI 9207 Conversion Speed Control
The NI 9207 converts at two pre-defined rates, as controlled by the speed control field.
Note
The conversion rate assumes that 16 channels are in the scan list.
Table 18.
NI 9207 Vendor Configuration Extensions
Index
Sub
Type
R/W
Description
0x2001
0
ARR:U32
—
Scan List = 17
1
R
Channels to Convert = <1..16>,
default = 16
2..17
R/W
Channel Code
0x2002
0
U32
R/W
Conversion Speed Control = 0 or 1,
default = 1
