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Chapter 5 Calibration 33

Figure 5-1: PCL-1713 VR assignment

The following list shows the function of each VR:

VR Function

VR1 A/D full scale (gain)

VR2 A/D bipolar offset

VR3 A/D unipolar offset

VR4 PGIA initial offset

TP1 PGIA output

5.3 A/D Calibration

Regular and accurate calibration procedures ensure the maximum

possible accuracy. The ADCAL.EXE calibration program leads you

through the whole A/D offset and gain adjustment procedure. The

basic steps are outlined below:

1. Set analog input channel AI0 as single-ended, bipolar, range

±5 V and connect to the ground.

2. Read TP1 as VG1.

3. Change AI0 range to ±0.625 V and read TP1 as VG8.

4. Adjust VR4 until -0.05 mV < VG1 - VG8 < 0.05 mV.

5. Repeat steps 1 ~ 4 until ther is no more need to adjust VR4.

6. Set analog input channel AI0 as single-ended, bipolar, range ±5 V,

and set AI1 as single-ended, unipolar, range 0 to 10 V.

7. Connect a DC voltage source with value equal to 0.5 LSB

(-4.9959 V) to AI0.

8. Adjust VR2 until the output codes from the card's AI0 flickers

between 0 and 1.

9. Connect a DC voltage source with a value of 4094.5 LSB (4.9953 V)

to AI0.

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Advantech PCI-1720 Manuale Utente Pagina 37