Operation Theory
23
3.2.3
AI Data Format
The ADC data of the PCIe-9842 is on the 14 MSB of the 16-bit A/D
data. The 2 LSB of the 16-bit A/D data should be truncated by soft-
ware when SDI function does not enable. When SDI function
enabled, the 2 LSB, bit 0 and bit 1, represent the SDI0 and SDI1,
respectively. Refer to following table for the A/D data structure with
SDI enabled or disabled.
A/D data format with SDI Enabled
D15 D14 D13 D12
………………….
D3 D2 D1 D0
D15 ~ D2 bits represent the data from ADC (2’s complement)
D1,D0 bits represent the status of SDI0 & SDI1, respectively
A/D data format with SDI Disabled
D15 D14 D13 D12 …………………… D3 D2 D1 D0
D15 ~ D2 bits represent the data form ADC (2’s complement)
D1, D0 bits should be truncated.
Description
Analog Input Range Digital Code (HEX)
Full-Scale Range
±1 V
Least Significant Bit
122
μ
V
FSR – 1 LSB
1.000 V
7FFC
Mi 1 LSB
0.000122 V
0001
Midscale
0 V
0000
Midscale – 1 LSB
-0.000122 V
FFFC
-FSR
-1.000 V
8004
Содержание PCIe-9842
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