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7.5.2 A/D conversion characteristics
(1) A/D conversion characteristics on voltage inputs
(For analog input range from -10 to 10V in a standard resolution mode)
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2001
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2004
Digital output
5.0000V
5.0025V
Input voltage
2.5mV
10V0-10V
-4000
0
4000
Digital output value
Analog input voltage
Figure 7.12 A/D conversion characteristics (voltage input)
A/D converter modules convert analog values input from other devices to digital
quantities so that CPUs can operate those values. On voltage inputs, for
example, A/D converter modules convert -10V to a quantity of -4000 and 10V to
4000. This means that the modules convert an input voltage of 2.5mV to a
digital quantity of 1, and abandon values smaller than 2.5mV.
(2) A/D conversion characteristics on current inputs
(For analog input range from 0 to 20mA in a standard resolution mode)
Digital output
10.000mA
10.005mA
Input current
5 A
20mA0-20mA
-4000
0
4000
Digital output value
Analog input current
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Figure 7.13 A/D conversion characteristics (current input)
The modules convert current an input of 0mA to 0 for an output, and 20mA to
4000. This means that the modules convert an input current of 5μA to a digital
quantity of 1, and abandon values smaller than 5μA.
REMARK
A voltage or current value that is equivalent to a digital value of 1 through A/D
conversion (maximum resolution) differs depending on the setting of the
resolution mode (1/4000, 1/12000, 1/16000) or the output range.