DL205 Analog Manual, 7th Edition Rev. D
5-20
Chapter 5: F2-08AD-2, 8-Ch. Analog Voltage Input
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A
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D
Analog Power Failure Detection
The analog module has a microcontroller which can diagnose analog input circuit problems. A
ladder rung can be added to program to detect these problems. This rung shows an input point
that would be assigned if the module was used as shown in the previous examples. A different
point would be used if the module was installed in a different I/O configuration.
Scaling the Input Data
Most applications usually require
measurements in engineering units which
provides more meaningful data. This is
accomplished by using the conversion
formula shown.
Adjustments may be needed to the formula
depending on the scale being used for the
engineering units.
For example, if pressure (PSI) is to be measured from 0.0–99.9 then multiply the value by 10
in order to imply a decimal place when viewing the value with the programming software or
with a handheld programmer. Notice how the calculations differ when the multiplier is used.
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V2000 K0
=
X37
OUT
C0
V-memory loc ationV2000 holds
channel 1data. Whenadatavalue
of zero is returned and inputX37 is
on,then theanalogcircuitry is not
operating properly.
V2000 K8000
=
OUT
C0
Pointers method
V-memory loc ationV2000 holds
channel 1data. When a datavalue
of 8000 is returned,then the analog
circuitry is not operatingproperly.
Units = A
H – L
4095
U = Engineering Units
A = Analog Value (0 – 4095)
H = High limit of the engineering
unit range
L = Low limit of the engineering
unit range
Units = A
H – L
4095
Units = 2024
100 – 0
4095
Units = 49
Units = 10A
H – L
4095
Units = 20240
100 – 0
4095
Units = 494
Analog Value of 2024, slightly less than half scale, should yield 49.4 PSI.
Example without multiplier Example with multiplier
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