DL205 Analog Manual, 7th Edition Rev. D
8-15
Chapter 8: F2-02DA-1, F2-02DA-1L, 2-Channel Analog Current Output
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Calculating the Digital Value
The control program must calculate the
digital value that is sent to the analog
output. Several methods can be used to do
this, but the best method is to convert the
values to engineering units. This is accom-
plished by using the formula shown.
Adjustments may have to be made to the
formula depending on the scale of the
engineering units.
Consider the following example which
controls pressure from 0.0 – 99.9 PSI.
Using the formula will calculate the digital
value to be sent to the analog output. The example shows the conversion required to yield
49.4 PSI. The multiplier of 10 is because the decimal portion of 49.4 cannot be loaded in the
program, so it is shifted right one decimal place to make a usable value of 494.
Analog and Digital Value Conversions
It is sometimes useful to do quick conversions between the signal levels and the digital values.
This can be helpful during startup or troubleshooting. The following table shows some
formulas help with the conversions.
For example, to covert a 10mA signal level
to a digital value, substitute 10 for A and
complete the math as shown in the example
to the right.
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A = U 4095
H – L
A = Analog Value (0 – 4095)
U = Engineering Units
H = High limit of the engineering
unit range
L = Low limit of the engineering
unit range
A = 10U 4095
10 (H – L)
A = 494 4095
1000 – 0
A = 2023
Range
If the digital value is known
If the analog signal level is known.
4 – 20mA
A = 16D + 4
4095
D = 4095 (A 4)
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D = 4095 (A – 4)
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D = 4095 (10mA – 4)
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D = (255.93) (6)
D = 1536
Summary of Contents for DL205
Page 1: ...DL205 Analog I O Manual Manual Number D2 ANLG M ...
Page 2: ...Notes ...
Page 6: ...Notes ...
