HP (Hewlett-Packard) PCI-9111DG/HR Manual De Usuario
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Operation Theorem
4.1.6
A/D Data Format
The A/D data read from the FIFO is in the two‘s complement format. As
the A/D gain is 1, the A/D signal range is roughly +10V ~ -10V bi-polar. In
PCI-9111HR, the whole 16 bits A/D data are available. The relationship
between voltage and the A/D data value is shown in the following table:
the A/D gain is 1, the A/D signal range is roughly +10V ~ -10V bi-polar. In
PCI-9111HR, the whole 16 bits A/D data are available. The relationship
between voltage and the A/D data value is shown in the following table:
A/D Data (Hex)
Decimal Value
Voltage (Volts)
7FFF
+32767
+9.99969
4000
+16384
+5.00000
0001
1
+0.00031
0000
0
0.00000
FFFF
-1
-0.00031
C000
-16384
-5.00000
8001
-32767
-9.99969
8000
-32768
-10.00031
Note:
the decimal value of the A/D data is in the same sign with the
bi-polar voltage. Therefore, the sign extension conversion is not
necessary.
bi-polar voltage. Therefore, the sign extension conversion is not
necessary.
The A/D converted data of 12 bits PCI-9111DG is on the 12 MSBs of the
A/D data. The 4 LSB of the 16 bits A/D data are the channel number and
must be truncated by software. The relationship between voltage and the
A/D converted data value is shown in the following table:
A/D data. The 4 LSB of the 16 bits A/D data are the channel number and
must be truncated by software. The relationship between voltage and the
A/D converted data value is shown in the following table:
A/D Converted
Data (Hex)
Decimal Value
Voltage (Volts)
7FF
+2047
+9.9951
400
+1024
+5.0000
001
+1
+0.0049
000
0
0.0000
FFF
-1
-0.0049
C00
-1024
-5.0000
801
-2047
-9.9951
800
-2048
-10.0000
The formula between the A/D converted data and the voltage value is:
Voltage
AD data
K
gain
=
× ×
_
1
10
where gain is the value of the A/D gain control register. K=32768 for
PCI-9111HR, and K=2048 for PCI-9111DG.
PCI-9111HR, and K=2048 for PCI-9111DG.