Table 9-1: SDI-12 command list
Commands
1
Responses
Remarks
aC1!
05041<CR><LF>
Start concurrent measurement. Average depth
and individual depth data at each sample
point will be provided by
aD0!
through
aD8!
.
aD0!
depth<CR><LF>
Average depth.
aD1!
thru
aD8!
36 individual sample data Grouped in 8 packets.
aR0!
+depth<CR><LF>
Similar to
aD0
for continuous measurement
mode.
aXA!
0601
Perform automatic calibration to determine
installation angle and height.
aXTxx!
Where xx is the
desired threshold
xx<CR><LF>
Set the heater threshold value (default is 0 °C).
The heater will turn on when the internal tem-
perature drops below this value and will
remain on until the temperature climbs above
the threshold. The allowed values range from
–40 to 10 °C.
aXHxx
Where xx is the
height in mm
xx<CR><LF>
Manually set the current sensor height in mm.
This option would only be used if the auto-
matic calibration fails due to problems in the
target area.
aXGxx!
0501
Reset the sensor ground level. This command
would be used with the offset if there is exist-
ing snow on the ground when the sensor is
installed.
1
"a” refers to the address of the sensor.
9.2 RS-232 sensor measurements
The SDMS40 measures the current snow depth at a user-programmable interval (minutes) and
transmits data on its RS-232 serial data lines to an external device, such as a data logger. By
default, the sensor is in polling mode, where measurements are triggered by request from a data
logger.
(p. 14) is a list of RS-232 commands in the command mode.
SDMS40 Multipoint Scanning Snowfall Sensor
13
