Advantech PCI-1713, User Manual

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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 V
G1
.
3. Change AI0 range to
±
0.625 V and read TP1 as V
G8
.
4. Adjust VR4 until -0.05 mV < V
G1
- V
G8
< 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.