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Appendix D. SDI-12 Sensor Support
D-2
TABLE D-1. Campbell Scientific Sensor SDI-12 Command and
Response Set
Name
Command
Response
1
Start Concurrent
Measurement and
Request CRC
aCC!
aCC1!
...
aCC9!
atttnn<CR><LF>
Send Data
aD0!
...
aD9!
a<values><CR><LF>
or
a<values><CRC><CR><LF>
Extended
Commands
aXNNN!
a<values><CR><LF>
1
Information on each of these commands is given in following sections.
D.2.1 Acknowledge Active Command (a!)
The Acknowledge Active command (
a!
) is used to test a sensor on the SDI-12
bus. An active sensor responds with its address.
D.2.2 Send Identification Command (aI!)
Sensor identifiers are requested by issuing command
aI!
. The reply is defined
by the sensor manufacturer but usually includes the sensor address, SDI-12
version, manufacturer’s name, and sensor model information. Serial number or
other sensor specific information may also be included.
aI!
allccccccccmmmmmmvvvxxx...xx<CR><LF>
a
Sensor SDI-12 address
ll
SDI-12 version number (indicates compatibility)
cccccccc
8-character vendor identification
mmmmmm 6 characters specifying the sensor model
vvv
3 characters specifying the sensor version (operating system)
xxx…xx
Up to 13 optional characters used for a serial number or other
specific sensor information that is not relevant for operation of the
data logger
<CR><LF> Terminates the response
Source:
SDI-12: A Serial-Digital Interface Standard for Microprocessor-Based Sensors
(see Appendix
D.2.3 Start Verification Command (aV!)
The response to a Start Verification command can include hardware
diagnostics, but like the
aI!
command, the response is not standardized.
Command:
aV!
Response:
atttn<CR><LF>
a
= sensor address
ttt
= time, in seconds, until verification information is available