Operation Theory
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Note:
Since the analog signal is sampled when an A/D conversion starts
(falling edge of A/D_conversion signal), while SDI<1..0> are sam-
pled right after an A/D conversion completes (rising edge of
nADBUSY signal). Precisely SDI<1..0> are sampled within 220 to
400ns lag to the analog signal, due to the variation of the conver-
sion time of the A/D converters.
Table 5 and 6 illustrate the ideal transfer characteristics of various input
ranges of DAQ \PXI-20XX. The converted digital codes for DAQ\PXI-2010
are 14-bit and 2’s complement, and here we present the codes as hexa-
decimal numbers. Note that the last 2 bits of the transferred data, which are
the synchronous digital input (SDI), should be ignored when retrieving the
analog data.
Description
Bipolar Analog Input Range
Digital code
Full-scale Range
±10V
±5V
±2.5V
±1.25V
Least significant bit
1.22mV
0.61mV
0.305mV
0.153mV
FSR-1LSB
9.9988V 4.9994V 2.4997V
1.2499V
1FFF
Mi1LSB
1.22mV
0.61mV
0.305mV
0.153mV
0001
Midscale
0V
0V
0V
0V
0000
Midscale –1LSB
-1.22mV -0.61mV -0.305mV -0.153mV
3FFF
-FSR
-10V
-5V
-2.5V
-1.25V
2000
Table 5: Bipolar analog input range and the output digital code on
DAQ/PXI-2010 (Note that the last 2 digital codes are SDI<1..0>)
Description
Unipolar Analog Input Range
Digital code
Full-scale Range
0V to 10V 0 to +5V
0 to +2.5V
0 to +1.25V
Least significant bit 0.61mV
0.305mV
0.153mV
76.3uV
FSR-1LSB
9.9994V
4.9997V
2.9999V
1.2499V
1FFF
Mi1LSB
5.00061V 2.50031V 1.25015V
625.08mV
0001
Midscale
5V
2.5V
1.25V
625mV
0000
Midscale –1LSB
4.99939V 2.49970V 1.24985V
624.92mV
3FFF
-FSR
0V
0V
0V
0V
2000
Table 6: Unipolar analog input range and the output digital code on
DAQ/PXI-2010 (Note that the last 2 digital codes are SDI<1..0>)
