D
3--
04
A
D
4-
C
ha
nn
el
A
na
lo
g
In
pu
t
2--9
D3--04AD 4-Channel Analog Input
The upper register also contains two
additional outputs that can be used to
choose a single channel for scanning.
These outputs are
ignored
if the channel
scan output is turned on.
(Note, our example shows outputs 114
and 115. Your output point will depend on
where you have installed the module.)
Out 114
Out 115
Channel
Off
Off
1
On
Off
2
Off
On
3
On
On
4
R011
MSB
LSB
1
1
0
1
1
7
1
1
6
1
1
5
1
1
4
1
1
3
1
1
2
1
1
1
-- scan a single channel
The first four points of the upper register
are used as inputs to tell the CPU which
channel
is
being
processed.
(Remember, the previous bits only tell
the module which channels to scan.) In
our example, when input 110 is on the
module is telling the CPU it is processing
channel 1. Here’s how the inputs are
assigned.
Input
Active Channel
110
1
111
2
112
3
113
4
R011
MSB
LSB
1
1
0
1
1
7
1
1
6
1
1
5
1
1
4
1
1
3
1
1
2
1
1
1
-- channel selection inputs
Single Channel
Scan Outputs
Active Channel
Selection Inputs
