4 analog output to strip chart – Campbell Scientific CR7 Measurement and Control System User Manual
Page 86
SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
8-4
Input Location Assignments:
1:TEMP DEG C
10:30 SEC 0
*
1
Table 1 Programs
01:
.5
Sec. Execution Interval
01:
P18
Time
01:
0
Tenths of seconds into minute
(maximum 600)
02:
300
Mod/by
03:
10
Loc [:30 SEC 0 ]
02:
P17
Panel Temperature
01:
1
IN Card
02:
1
Loc [:REF TEMP ]
03:
P14
Thermocouple Temp (DIFF)
01:
1
Rep
02:
13
15 mV fast Range
03:
1
IN Card
04:
2
IN Chan
05:
2
Type E (Chromel-Constantan)
06:
1
Ref Temp Loc REF TEMP
07:
2
Loc [:TC TEMP ]
08:
1
Mult
09:
0
Offset
04:
P
89 If X<=>F
01:
10
X Loc 30 SEC 0
02:
4
<
03:
.5
F
04:
10
Set high Flag 0 (output)
05:
P
71 Average
01:
1
Rep
02:
2
Loc TC TEMP
06:
P
End Table 1
8.4 ANALOG OUTPUT TO STRIP
CHART
This example illustrates the use of the Analog
Output Instruction 21 to output 2 analog
voltages to strip chart.
While of questionable value because of power
requirements and strip chart reliability, some
archaic regulations require strip chart backup
on weather data. Instruction 21 may be used
with the CR7 to provide two continuous analog
outputs for strip charts. The output values in
this example are wind speed and wind direction.
The following program measures the sensors
every five seconds. The readings are moved to
another two locations and scaled to a 0 to 1000
millivolt output for the strip chart. Wind direction
is changed from a 0-360 degree input to output
representing 0 to 540 degrees. This conversion
is done in a subroutine which is described in the
next example.
The example also includes instructions to
output wind vector every hour.
Input Location Assignments:
01:WS
02:0-360 WD
03:0-540 WD
04:WS output
05:WD output
*
1
Table 1 Programs
01:
3
Sec. Execution Interval
01:
P3
Pulse
01:
1
Rep
02:
5
IN Card
03:
1
Pulse Input Chan
04:
22
Switch closure; Output Hz.
05:
1
Loc [:WS ]
06:
1.789
Mult
07:
1
Offset
02:
P4
Excite,Delay,Volt(SE)
01:
1
Rep
02:
16
500 mV fast Range
03:
2
IN Card
04:
1
IN Chan
05:
1
EX Card
06:
1
EX Chan
07:
1
Meas/EX
08:
2
Delay (units .01sec)
09: 1000
mV Excitation
10:
2
Loc [:0-360 WD ]
11:
.72
Mult
12:
0
Offset
03:
P86
Do
01:
1
Call Subroutine 1