Measurement-computing PCI-DAS6071 Manuel d'utilisateur télécharger pdf (Page 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

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Measurement-computing PCI-DAS6071 Manuel d'utilisateur Page 32