Omega Engineering DAQ-12 - Manual (Page 13)

The final stage of the A/D converter circuit is the A/D converter IC. The converter must be
configured for unipolar or bipolar input voltages as shown in Figure 2-3. When configured
for unipolar operation, the analog input multiplied by the gain setting must be in the range of
0 volts (analog ground) to +10 volts. When configured for bipolar operation, the analog
input multiplied by the gain setting must be in the range of -5 volts to +5 volts.
Bipolar
1 2 3
4 5 6
J6
Unipolar
1 2 3
4 5 6
J6
Figure 2-3. Jumper J6 Configuration
WARNING: The user must ensure that the maximum input voltage multiplied by the
amplifier gain does not exceed the range of 0 to +10 volts for unipolar operation or -5 to
+5 volts for bipolar operation.
Although the A/D converter produces 12-bit digital 'codes' to represent the input voltage, the
DAQ-12 converts these 'codes' into standard 16-bit signed integer values before returning
them to the PC. When the A/D converter is configured for unipolar operation, the DAQ-12
returns values in the range of 0 to 4095. When configured for bipolar operation, values in the
range of -2048 to +2047 are returned.
In order to calculate the actual input voltage from the value provided by the DAQ-12, the user
must know the configuration (unipolar / bipolar) and the gain setting used to acquire the
data. Given this information, the input voltage can be calculated using the following
equations:
Unipolar mode: input = *
CODE
4096
10V
GAIN
Bipolar mode: input = *
CODE
2048
5V
GAIN
DAQ-12 Users Manual 13