0D0!
Answer:
0+2591+706+25.53+0<CR><LF>
The first values in the response to the
aDn!
command is the sensor address.
Trigger measurement
The command
aM!
with sensor address
a
triggers a measurement as in the example below.
The response states the measurement duration and the number of measurement values (see
example below). After completion of the measurement, the device will return an additional
a<CR><LF>
, with
a
the sensor address.
EXAMPLE
0M!
Answer:
00084<CR><LF>
and
0<CR><LF>
after 8 seconds
The answer contains the following information:
0
SDI-12 address
008
Duration of the measurement in seconds
4
Number of measurement values
Request results
After each measurement, results are requested with the command
aDn!
, with
a
the sensor address
and
n
the index of the returned data string.
EXAMPLE
0D0!
Answer:
0+2591+706+25.53+0<CR><LF>
The leading
0
of the response is the sensor address.
Generally, the command
aD0!
is sufficient to request up to 9 measurement values. If more than 9
values need to be read, or if the values are returned in groups, the commands
aD1!
,
aD2!
,… may
need to be issued after
aD0!
. For example, if a measurement returns 8 values in two groups of 4, the
commands
aD0!
and
aD1!
need to be issued to receive all values.
Acquire continuous measurements
If the SDI-12 device is operating in continuous measurement mode (not polled by SDI-12), the com-
mand
aR0!
will request and return the current reading of the sensor. The values within the data
1
2
C
o
m
m
u
n
ic
at
io
n
Manual
77
