Converting 0-360 Wind Direction Output To 0-540 For Strip Chart - Campbell Measurement and Control Module CR10 Operator's Manual
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Also See for Measurement and Control Module CR10:
- Instruction manual (34 pages) ,
- Replacement procedure (8 pages) ,
- Operator's manual (23 pages)
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SECTION 8. PROCESSING AND PROGRAM CONTROL EXAMPLES
09:
P
01:
4
02:
30
03:
5
10:
P92
01:
0
02:
60
03:
10
11:
P69
01:
1
02:
180
03:
00
04:
1
05:
2
12:
P71
01:
2
02:
3
13:
P
8.7 CONVERTING 0-360 WIND
DIRECTION OUTPUT TO 0-540 FOR
STRIP CHART
If 0-360 degree wind direction is output to a strip
chart the discontinuity at 0/360 will cause the pen
to jump back and forth full scale when the winds
are varying from the north. In the days of strip
charts this was solved with a 0-540 degree pot on
the wind vane (direction changes from 540 to 180
and from 0 to 360 so the pen only jumps once
when the wind is out of the north or south).
When faced with the necessity of strip chart
output (see previous example), the following
algorithm can be used to change a 0-360
degree input to 0-540. (If you have a 0-540 pot,
it can be used with the CR10 since the Wind
Vector Instruction, 69, will work with this
output.)
To change 0-360 degrees to the 0-540 degrees,
360 degrees must sometimes be added to the
reading when it is in the range of 0 to 180. The
following algorithm does this by assuming that if
the previous reading was less than 270, the
vane has shifted through 180 degrees and does
not need to be altered. If the previous 0-540
reading was greater than 270, 360 degrees is
added.
8-8
103 SDM-A04
Reps
Address
Loc WS output
If time is
minutes into a
minute interval
Set high Flag 0 (output)
Wind Vector
Rep
Samples per sub-interval
Polar Sensor/(S ,D1, SD1)
Wind Speed/East Loc WS
Wind Direction/North Loc
0-360 WD
Average
Reps
Loc Ta
End Table 1
This example is written as a subroutine which is
used by the previous example to output an
analog voltage to a strip chart.
Input Location Labels:
2:0-360 WD
6:0-540 out
10:0-540 WD
*
3
Table 3 Subroutines
01:
P85
Beginning of Subroutine
01:
1
Subroutine Number
02:
P89
If X<=>F
01:
10
X Loc 0-540 WD
02:
3
>=
03:
270
F
04:
30
Then Do
03:
P86
Do
01:
11
Set high Flag 1
04:
P94
Else
05:
P86
Do
01:
21
Set low Flag 1
06:
P95
End
07:
P31
Z=X
01:
2
X Loc 0-360 WD
02:
10
Z Loc [:0-540 WD]
08:
P89
If X<=>F
01:
10
X Loc 0-540 WD
02:
4
<
03:
180
F
04:
30
Then Do
09:
P91
If Flag/Port
01:
11
Do if flag 1 is high
02:
30
Then Do
10:
P34
Z=X+F
01:
10
X Loc 0-540 WD
02:
360
F
03:
10
Z Loc [:0-540 WD]
11:
P31
Z=X
01:
10
X Loc 0-540 WD
02:
6
Z Loc [:0-540 out]
12:
P95
End
13:
P95
End
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