Software A/D Offset Calibration; Utilities; 9113Util - NuDAQ PCI- 9113A User Manual

5. Set the analog gain = 1 and channel number #0 by software.
6. Short the A/D channel 0 (pin 1 of CN1) to ground (GND).
7. Adjust VR3 to obtain reading between 2047~2048.
8. Applied a +10V reference input signal to A/D channel 0 (pin 1 of CN1),
and trim the VR2 to obtain reading between 4094~4095.
7.1.3

Software A/D Offset Calibration

For more accuracy calibrate the input offset signal, using software to
calibrate the offset of the analog input signal is a good approach. Another
benefit is this method can calibrate offset online and thus eliminate any
temperature drift. For example, user can short the resistor RB1 to
ground. Measuring the digital value of channel #0 can obtain the offset
voltage of the AD channels. If the digital offset value is Voff, user can
modify any AD data by subtracting Voff from the AD data to obtain the
offset calibrated value. Note that the Voff may be different for each gain
level,. Users should calibrate the offset value for every gain value.
7.2

Utilities

This software CD provides two utility programs. They are 9113Autil.exe
which provides three functions, System Configuration, Calibration, and
Functional Testing, and I_eeprom which is used to enable or disable
interrupt of PCI-9113A board. The utility programs are described in the
following sections.
7.2.1

9113UTIL

There are three functions provided by 9113UTIL. They are System
Configuration, Calibration, and Functional Testing. This utility software is
designed as menu-driven based windowing style. Not only the text
messages are shown for operating guidance, but also has the graphic to
indicate you how to set right hardware configuration.
Calibration and Utilities 71