CR10X User Guide
8-12
10:
P92
If time is
01:
0
minutes into a
02:
60
minute interval
03:
10
Set high Flag 0 (output)
11:
P69
Wind Vector
01:
1
Rep
02:
180
Samples per sub-interval
03:
00
US, DV, SD (Polar Sensor)
04:
1
Wind Speed/East Loc WS
05:
2
Wind Direction/North Loc 0-360 WD
12:
P71
Average
01:
2
Reps
02:
3
Loc Ta
13:
P
End Table 1
8.7 Converting 0-360 Wind Direction Output to 0-540
For Strip Chart
If 0-360 degree wind direction is sent to a strip chart the discontinuity at 0/360
causes 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
potentiometer on the windvane (direction changes from 540-180 and from 0-360
so the pen only jumps once when the wind is from the north or south).
When faced with the necessity for 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 potentiometer, it can be used with the CR10X since Instruction 69,
Wind Vector, will work with this output.)
To change 0-360 degrees to 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 the reading does not need to be altered. If the
previous 0-540 reading was greater than 270, 360 degrees is added.
This example is written as a subroutine which is used by the previous example to
output an analogue 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