Deterministic Ethernet Expansion Chassis User's Guide

NI 9233 Calibration Data

The NI 9233 has four input channels with a fixed gain. The inputs are

AC-coupled so calibration is done with a sine wave rather than with DC

signals. The specification derivations are based on calibration at 250 Hz,

acquired at 25 kS/s. The AC response (flatness) changes with both input

frequency and sample rate; therefore, calibrating at different signal

frequencies or at different sample rates gives different results.

Each channel has an associated LSB weight, which is the number of volts

per bit, and an offset.

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

corrected data:

10.000 kS/s 1 00101 10 0x96 2.56 MHz

6.250 kS/s 1 01000 10 0xA2 1.60 MHz

5.000 kS/s 1 01010 10 0xAA 1.28 MHz

3.333 kS/s 1 01111 10 0xBE 853 kHz

3.125 kS/s 1 10000 10 0xC2 800 kHz

2.500 kS/s 1 10100 10 0xD2 640 kHz

2.000 kS/s 1 11001 10 0xE6 512 kHz

Table 45. NI 9233 Scan List Format

Coefficient Representation Units Default Value

LSB Weight Unsigned pV/LSB 0x0009D292

(643.73 nV/bit)

Offset Signed nV 0x00000000

(0 nV)

Table 44. NI 9233 Calibration Data (Continued)

Data Rate

Turbo

Disable

Clock

Divisor

Clock

Source

Configure

ADC

Oversample

Clock Rate

Calibrated_Data =Binary_Data LSB_Weight× Offset–