Measurement Computing PCI-DAS6071 - Manual (Page 32)

32
Chapter 4
Calibrating the Board
Introduction
You should calibrate the board (using the InstaCal utility) after the board has fully warmed up. The
recommended warm-up time is 15 minutes. For best results, calibrate the board immediately before making
critical measurements. The high resolution analog components on the board are somewhat sensitive to
temperature. Pre-measurement calibration ensures that your board is operating with the optimum calibration
values.
Calibration theory
Analog inputs are calibrated for offset and gain. Offset calibration for the analog inputs is performed directly on
the programmable gain input amplifier (PGIA), with coarse and fine trim DACs acting on the amplifier.
For input gain calibration, a precision calibration reference is used with coarse and fine trim DACs acting on the
ADC (see Figure 38).
Figure 38. Analog input calibration - basic elements