ADLINK Technology NuDAQ PCI-9114DG, User Manual

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Operation Theorem
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31
Under this mode, an interrupt signal is generated when FIFO becomes
half-full. It means there are 512 words data in the FIFO already. The ISR
can read a block of data every interrupt occurring. This method is very
convenient to read A/D in size of a “block” (512 words) and it is benefit for
software programming.
4.1.5 A/D Data Format
The range of A/D data read from the FIFO port is from -32768 to 32767.
As the A/D gain is 1, the A/D signal range is -10V ~ +10V. The
relationship between the voltage and the value is shown in the following
table:
Voltage (Volts)
A/D Data (Hex) Decimal Value
± 10V (Bipolar)
7FFF 32767 +9.9997
4000 16384 +5.0000
0001 1 +0.0003
0000 0 +0.0000
FFFF -1 -0.0003
C000 -16385 -5.0000
8001 -32767 -9.9997
8000 -32768 -10.0000
The formula between the A/D data and the analog value is
Voltage = ( AD_Data * 10 ) / (32768 * gain ) --Bipolar
where the gain is 1,10,100, 1000 for HG version or 1,2,4,8 for DG
version.