Multiplexer - Campbell 21X Operator's Manual

redirected
tol
Final Storage
Area
1, the
time
is
output and
t|pe
total is sampled.
I
InRut
Locatijn
Labels:
P80
3
2
P72
1
1
P8q
4
4
q
3q
P80
1
2q
P7V,
22Q
08:
P7g
01:
11
02:
2
Pe5
P
Table 1 Programs
Sec. Execution lnterval
Pulse
Rep
Pulse Input Chan
Switch closure
Loc [:Rain (mm)]
Mult
Offset
lf
time
is
minutes into a
minute interval
Set high Flag
0 (output)
Set Active Storage Area
Input Storage Area
Array lD or location
Totalize
Rep
Loc Rain (mm)
lf X<=>F
X Loc
1Smin
tot
F
Then
Do
Set Active Storage Area
Final Storage Area
Array lD or location
RealTime
Day,Hour-Minute
Sample
Rep
Loc 1smin tot
End
End
Table
1
SECTION
8.
PROCESSING
AND PROGRAM CONTROL EXAMPLES
1:Rain (mm)
2:1Smin
tot
*1
01:
60
01:
01:
o2'.
03:
o4:
05:
06:
02:
P92
01:
0
02:
15
03:
10
P3
1
1
2
1
es4
0l
8.3
USING CONTROL PORTS AND
LOOP TO RUN AM416 MULTIPLEXER
This example uses an AM416 to measure 16
copper-constantan
thermocouples and 16 Model
223
soil moisture blocks. The sensors are read
every
ten minutes and the average value output
once an hour. The multiplexer is housed
in
an
AM-ENCT enclosure
to minimize thermocouple
errors
created by thermal gradients.
Thermocouple Wire is
run
from the 21X to the
AM416
common used for the TC measurements
and
the 21X panel temperature is used for the
reference temperatu re.
The
AM416 switches lhe 223 moisture block out
of the circuit
when it is not being measured.
This eliminates the need for the blocking
capacitors used
in
the model 227 soil moisture
block.
The
223 blocks are about one fifth the
cost of lhe 227 blocks.
Control ports are used to reset the AM416 and
clock
it
through its
channels. The sequence of
the program
is:
Measure
the 21X panel temperature
for TC temperature reference.
21X sets
the port high which resets the
AM416.
A loop is
entered; within
each pass:
The port clocking the AM416 is pulsed.
The
connected TCs and moisture blocks
are measured.
21X sets the port controlling AM416 reset
low.
Soil moisture measurements are converted
to block resistances.
The input location
in
which the temperature and
soil moisture measurements are stored
is
indexed to
the loop counter (lnstruction
87,
Section 12). An indexed location is incremented
by one with each pass through
the
loop.
For
example, on the
first pass temperature is stored
in Location
2,
and
soil moisture in Location
18.
On
the second pass temperature is stored
in
Location 3, and soil moisture in Location
18.
After 16 loop passes, temperature and soil
moisture measurements
occupy Locations 2
through
17
and
18
through 33, respectively.
Connections are shown in Figure 8.3-1.
03:
01:
02:
04:
01:
02:
05:
01:
02:
03:
o4:
06:
01:
02:
07:
01:
09:
10:
8-3