Section 7
Parameter Settings
56
FT742-SM (RS422 & RS485) Sensors
– User Manual
7.4.13 FL.2: Set or Query Filter Lengths
Command
Parameter
FL (lengths)
Command
Syntax
SET Sensor:
$<listenerID>,FLL<speedLen>,<dirLen>*<checksum><cr>
<lf>
$aa,FLLxxxx,xxxx*hh<cr><lf>
QUERY Sensor:
$<listenerID>,FL?L*<checksum><cr><lf>
$aa,FL?L*hh<cr><lf>
Sensor output:
$<talkerID>,FL=<speedLen>,<dirLen>*<checksum><cr><l
f>
$aa,FL=xxxx,xxxx*hh<cr><lf>
Parameters
<speedLen>
0001 to 0064
Sample size of the wind speed filter.
Number of previous readings
#
used to calculate the latest wind speed
reading, 0001 is equivalent to disabling the filter
(Factory Default Setting = 0016)
<dirLen>
0001 to 0064
Sample size of the wind direction filter.
Number of previous readings
#
used to calculate the latest wind
direction reading, 0001 is equivalent to disabling the filter;
(Factory Default Setting = 0016)
Examples
Example 3
Modify the filter’s dimensions. Verify that the command has been accepted.
Message
Comment
$01,FLL0001,0032*//<cr><lf>
Set speed filter length to 1 and
direction filter length to 32.
$01,FL?L*//<cr><lf>
Query filter’s length settings.
$WI,FL=0001,0032*29<cr><lf>
Sensor response.
Description
Use this command to modify the speed and direction filter lengths. When the filter is
enabled, speed and direction readings are independently averaged by calculating the mean
of the previous number of readings
#
set by the filter lengths <speedLen> and <dirLen>.
# Please note the previous readings filter length by definition includes the most up to date
wind reading at position 1. So setting a filter to a length of 0001 gives just the current
reading (see Section 2.3).
The sensor
’s internal memory is large enough to retain 64 previous speed and direction
readings, allowing for maximum filter length of 6.4 seconds.
