Calibration Dacs; Reference Calibration - National Instruments DAQ AT-MIO-16X User Manual

Chapter 6 Calibration Procedures

Calibration DACs

Analog
Input CALDAC0
CALDAC1
CALDAC2
CALDAC3
CALDAC8
Output CALDAC4
CALDAC5
CALDAC6
CALDAC7

Reference Calibration

AT-MIO-16X User Manual
It is important to realize that inaccuracy of the internal voltage
reference results only in gain error. Offset error is unaffected. If an
application can tolerate slight gain inaccuracy, there should not be a
need to redetermine the value of the onboard reference.
There are eight 8-bit DACs (CALDAC<0..7>) and one 12-bit DAC
(CALDAC8) on the AT-MIO-16X that are used for calibration. These
DACs are described in Table 6-2.
Table 6-2. Calibration DACs
DAC
Coarse gain trim
Fine gain trim
Coarse postgain offset trim
Fine postgain offset trim
Pregain offset trim
DAC0 gain trim
DAC1 gain trim
DAC0 offset trim
DAC1 offset trim
The AT-MIO-16X has a stable voltage reference to which gain can be
calibrated. The value of this voltage reference is determined through the
reference calibration routine, which requires a known external voltage
between 5 and 9.99 V to be connected differentially on any desired
input channel. The routine calibrates the circuitry to the external
reference and then reads the internal reference. This value is stored as
Function
6-8
Adjustment Incremental
Range
±1169 ppm –9.13 ppm
±65.1 ppm –0.509 ppm
±51.8 ppm 404 V
±512 V 4.00 V
±1.2 V 0.586 V
±976 ppm 7.62 ppm
±976 ppm 7.62 ppm
±4.86 mV 38.0 V
±4.86 mV 38.0 V
© National Instruments Corporation
Effect