8 |
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active level (about 15-20 mA) only during measurement time, otherwise current is usually less
than 0.5 mA.
Basic SDI-12 Command List
How it Works
Following is a list of the supported commands for the sensor. In the descriptions below, SDI-12
command/response sequences are show in Courier font, with a box surrounding the text. The
command from the SDI-12 Logger/Recorder is shown in bold text. The response from the sen-
sor is shown in normal text. As is normal, SDI-12 commands are always t
erminated with the ‘!’
character. Responses from the sensor always include the sensor’s address as the first character
and are always terminated with the <CR><LF> (carriage return-line feed) sequence.
Basic SDI-12 Command List
The
GroPoint™
Lite Profiling Probes respond to the following basic SDI-12 commands. In all
cases,
a
=
sensor address. Default sensor address is ‘0’.
Command
Meaning
Response
?!
Address Query
Device address (default address is ‘0’)
a
!
Acknowledge
Device address (default
address is ‘0’)
a
I!
Send Identification
Identification string
a
A
b
!
Change Address
Change device address to ‘
b
’
a
M!
a
M1!,
a
M2!
Start Moisture Measurement
Start Temp. Measurement
Measure time and count (e.g. “a0023”)
a
C!
a
C1!,
a
C2!
Start Concurrent Measurement
Measure time and count (e.g. “a00023”)
a
D0!
Send Data
Measurement values
All other commands received by the sensor will be acknowledged with the device address only.
Understanding the Basic Commands
Query Address Command: ?!
Use this command to query a sensor for its address. This will allow a user to determine the ad-
dress of a sensor if it is unknown. Please understand that if more than one sensor is connected
to the SDI-12 communication bus, they will all respond to this command, causing a bus conten-
tion, and usually a garbled response.