Section 7
Parameter Settings
42
FT742-SM (RS422 & RS485) Sensors
– User Manual
7.4.2
AT.1: Query the Acoustic Temperature
Command
Parameter
AT
Command
Syntax
SET Sensor:
N/A
QUERY Sensor:
$<listenerID>,AT?*<checksum><cr><lf>
$aa,AT?*hh<cr><lf>
Sensor output:
$<talkerID>,AT=<temp>,<units>,<status>*<checksum>
<cr><lf>
$aa,AT=±xxx.x,c,c*hh<cr><lf>
Parameters
<temp>
-077.8 to
+368.3
Read only parameter that returns the current acoustic temperature reading
in the range:
-61.0°C to +95.1°C
-77.8°F to +203.2°F
212.2K to 368.3K
<units>
C
The Acoustic Temperature is output in degrees Celsius
F
The Acoustic Temperature is output in degrees Fahrenheit
K
The Acoustic Temperature is output in Kelvin
<status>
A
The acoustic temperature reading is valid
V
An acoustic temperature reading is being acquired. The output may not be
valid during this time
Examples
Example 1
– Query Temperature °C
Query the latest acoustic temperature reading
– a valid reading in degrees Celsius.
Message
Comment
$01,AT?*//<cr><lf>
Query acoustic temperature
$WI,AT=+023.9,C,A*15<cr><lf>
Sensor response
Example 2
– Query Temperature °K
Query the latest acoustic temperature reading..
Message
Comment
$01,AT?*//<cr><lf>
Query acoustic temperature
$WI,AT=+297.2,K,V*0C<cr><lf>
Sensor response
Example 3 - CU AT DFC Mode
$WI,WVC=000.0,333,0,+026.4,C,A*4B
Comment
CUE mode with AT (DFC Mode)
Example 4
– WV DFC Mode
$WI,WVC=000.0,323,0,+026.3,C,A*4D
Comment
WV response (DFC Mode)
Description
The AT query command returns the current acoustic temperature reading in the selected units.
An acoustic temperature reading will be returned even if the sensor is in the process of trying to
acquire a valid reading. The acoustic temperature reading is filtered with a one-minute time
constant by default.
The accuracy of the acoustic temperature reading may be affected by the relative humidity of the
air surrounding the sensor. See Section 2.11 for further details.
Software version V7.5.1 introduced the option for AT (Acoustic Temperature) data to be inserted
within the CU & WV output data. A new DF command option (see Section 7.4.8) controls this
mode.
Caution: The acoustic temperature feature requires calibration at FT Technologies. If the
sensor has had a software upgrade to V7.5 (or above) then the data will be uncalibrated
and may not comply with the official specification.
