F
3-
-0
4A
D
S
4-
C
h.
Is
ol
at
ed
A
na
lo
g
In
.
3--10
F3--04ADS 4-Channel Isolated Analog Input
The remaining twelve bits represent the
analog data in binary format.
Bit
Value
Bit
Value
0 (LSB)
1
6
64
1
2
7
128
2
4
8
256
3
8
9
512
4
16
10
1024
5
32
11
2048
1
1
7
R001
MSB
LSB
0
1
0
1
1
6
1
1
5
1
1
4
1
1
3
1
1
2
1
1
1
1
1
0
0
1
7
0
1
6
0
1
5
0
1
4
0
1
3
0
1
2
0
1
1
-- data bits
R011
Since the module has 12-bit resolution, the analog signal is converted into 4096
“pieces” ranging from 0 -- 4095 (2
12
). For example, with a 0 to 10V scale, a 0V signal
would be 0, and a 10V signal would be 4095. This is equivalent to a a binary value of
0000 0000 0000 to 1111 1111 1111, or 000 to FFF hexadecimal. The following
diagram shows how this relates to each signal range.
+V
0V
--V
0
4095
--10V -- +10V
--5V -- +5V
+V
0V
0
4095
0V -- 10V
0V -- 5V
+5V
1V
0
4095
1V -- 5V
20mA
4mA
0
4095
4 -- 20mA
Each “piece” can also be expressed in
terms of the signal level by using the
equation shown. The following table
shows the smallest signal levels that will
result in a change in the data value for
each signal range.
Resolution
=
H
-
L
4095
H = high limit of the signal range
L = low limit of the signal range
Range
Highest Signal
Lowest Signal
Smallest Change
--10 to +10V
+10V
--10V
4.88 mV
--5 to +5V
+5 V
--5V
2.44 mV
0 to 5V
5V
0V
1.22 mV
0 to 10V
10 V
0V
2.44 mV
1 to 5V
5V
1V
0.98 mV
4 to 20mA
20mA
4mA
3.91
µ
A
Now that you understand how the module and CPU work together to gather and
store the information, you’re ready to write the control program.
Analog Data Bits