Campbell CR800 Series - Revision

Section 7. Installation
242
An active sensor responds to each command. Responses have several standard
forms and terminate with <CR><LF> (carriage return–line feed).
SDI-12 commands and responses are defined by the SDI-12 Support Group
(www.sdi-12.org) and are summarized in the table Standard SDI-12 Command &
Response Set
(p. 242). Sensor manufacturers determine which commands to
support. The most common commands are detailed in the table SDI-12
Commands for Transparent Mode
(p. 242).
SDI-12 Commands for Transparent Mode
Command Name
Command Syntax
1
Response
2
Notes
Break
Continuous
spacing for at least
12 milliseconds
None
Address Query ?! a<CR><LF>
Acknowledge Active a! a<CR><LF>
Change Address aAb!
b<CR><LF> (support for this command is required only
if the sensor supports software changeable addresses)
Start Concurrent Measurement aC! atttnn<CR><LF>
Additional Concurrent
Measurements
aC1! ... aC9! atttnn<CR><LF>
Additional Concurrent
Measurements and Request
CRC
aCC1! ... aCC9! atttnn<CR><LF>
Send Data aD0! ... aD9! a<values><CR><LF> or a<values><CRC><CR><LF>
Send Identification
aI!
allccccccccmmmmmmvvvxxx...xx<CR><LF>. For
example, 013CampbellCS1234003STD.03.01 means
address = 0, SDI-12 protocol version number = 1.3,
manufacturer is Campbell Scientific, CS1234 is the
sensor model number (fictitious in this example), 003 is
the sensor version number, STD.03.01 indicates the
sensor revision number is .01.
Start Measurement
3
aM! atttn<CR><LF>
Start Measurement and Request
CRC
3
aMC! atttn<CR><LF>
Additional Measurements
3
aM1! ... aM9! atttn<CR><LF>
Additional Measurements and
Request CRC
3
aMC1! ... aMC9!
atttn<CR><LF>
Continuous Measurements aR0! ... aR9! a<values><CR><LF> (formatted like the D commands)
Continuous Measurements and
Request CRC
aRC0! ... aRC9!
a<values><CRC><CR><LF> (formatted like the D
commands)
Start Verification
3
aV! atttn<CR><LF>