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Inputs and Outputs
DAC instruction
Voltage range
Allocation of digits to
voltage
12
Please pay attention to a low internal resistance of the power supply unit (of the
input signals), because it may have influence on the measuring accuracy. If
this is not possible:
– Depending on the output resistance a linear error is caused.
You can compensate this by multiplying the measurement value with a
corresponding factor and get a sort of recalibration.
– From approx. 3kΩ upwards the multiplexer settling time extends.
The waiting time defined in the standard instructions ADC and ADC12 is
then too short, so that imprecise values are recalled. In this case please
use the instructions described in chapter 5.3.1.
5.1.2 Analog Outputs
The system has 2 analog outputs (OUT1, OUT2) with BNC-plugs; with Gold-D
option the outputs are located on the DSub connector ANALOG OUT (see
Fig. 6). A digital-to-analog converter (DAC) is allocated to each of the outputs.
The standard instruction DAC (number, value) checks each of the values if
it exceeds or falls below of the 16-bit value range (0...65535). If the value is in
the 16-bit value range, the indicated value is output on the output number. If
it is not in the value range the maximum or minimum values are output, (see
also ADbasic manual).
5.1.3 Calculation Basis
The voltage range of the ADwin-Gold at the analog inputs and outputs is
between –10 V to +10 V (bipolar 10 V).
The 6 5536 digits are allocated to the corresponding voltage ranges of the
ADCs and DACs insofar that
– 0 (zero) digits correspond to the maximum negative voltage and
– 65535 digits correspond to the maximum positive voltage
The value for 65536 digits, exactly 10 Volt, is just outside the measurement
range, so that you will get a maximum voltage value of 9.999695V for the 16-
bit conversion and a voltage value of 9.998779V for the 14-bit conversion.
[V]
+10
0
0
-10
Fig. 8 – Zero offset in the standard setting of bipolar 10 Volt
32768
ADwin-Gold USB / ENET, manual version 3.8, October 2005
ADwin
65536
[Digit]
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