Appendix B Analog Input Channel, Gain Settings, and Voltage Calculation
NI-DAQ FRM for PC Compatibles B-4
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National Instruments Corporation
Internal Channel constants are defined in the following header files:
• C programmers—NIDAQCNS.H (DATAACQ.H for LabWindows/CVI)
• BASIC programmers—NIDAQCNS.INC (Visual Basic for Windows
programmers should refer to the Programming Language
Considerations section in Chapter 1, Using the NI-DAQ Functions, for
more information.)
• Pascal programmers—NIDAQCNS.PAS
Note When the channel is ND_INT_DEV_TEMP, you can compute the temperature from
the retrieved voltage by applying the following formulas:
For VX I MIO s:
For all other supported E series devices:
Table B-3. Internal Channel Purposes for Analog Input Devices
Internal Channel Purpose
ND_INT_AI_GND Analog Input Channels Offset
ND_INT_AO_GND_VS_AI_GND Ground Differential
ND_INT_AO_CH_0 Analog Output Channel 0 Offset/Linearity
ND_INT_AO_CH_1 Analog Output Channel 1 Offset/Linearity
ND_INT_CM_REF_5V Analog Input Channels Offset
ND_INT_REF_5V Analog Input Channels Gain
ND_INT_AO_CH_0_VS_REF_5V Analog Output Channel 0 Gain
ND_INT_AO_CH_1_VS_REF_5V Analog Output Channel 1 Gain
ND_INT_AO_CH_1_VS_AO_CH_0 Analog Output Channel 1 vs Analog Output Channel 0
ND_INT_DEV_TEMP Device Temperature
T°C
() Voltage 100
×()
32–
()
59
⁄×
=
T
°
C
() Voltage 100
×()
50–=