Table D-1: Campbell Scientific sensor SDI-12 command and response set
Name
Command
Response
1
Address Query
?!
a<CR><LF>
Change Address
aAb!
b<CR><LF>
Start Measurement
aM!
aM1!...aM9!
atttn<CR><LF>
Send Data
aD0!...aD9!
a<values><CR><LF> or
a<values><CRC><CR><LF>
1
Information on each of these commands is given in the following sections.
D.1.1 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.1.2 Send identification command (al!)
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 References).
CS650 and CS655 Water Content Reflectometers
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