Appendix C. SDI-12 sensor
support
SDI-12, Serial Data Interface at 1200 baud, is a protocol developed to simplify sensor and data
logger compatibility. Only three wires are necessary — serial data, ground, and 12 V. With unique
addresses, multiple SDI-12 sensors can connect to a single SDI-12 terminal on a Campbell
Scientific data logger.
This appendix discusses the structure of SDI-12 commands and the process of querying SDI-12
sensors. For more detailed information, refer to version 1.4 of the SDI-12 protocol, available at
www.sdi-12.org.
For additional information, refer to the SDI-12 Sensors | Transparent Mode and SDI-12 Sensors |
Watch or Sniffer Mode videos.
C.1 SDI-12 command basics
SDI-12 commands have three components:
l Sensor address (a) – a single character and the first character of the command. Use the
default address of zero (0) unless multiple sensors are connected to the same port.
l Command body – an upper case letter (the “command”), optionally followed by one or
more alphanumeric qualifiers.
l Command termination (!) – an exclamation mark.
An active sensor responds to each command. Responses have several standard forms and always
terminate with <CR><LF> (carriage return and line feed). Standard SDI-12 commands are listed
in Table C-1 (p. 41).
Table C-1: Campbell Scientific sensor SDI-12 command and response set
Name Command
Response
1
Acknowledge Active
a!
a<CR><LF>
Send Identification
aI!
allccccccccmmmmmmvvvxxx...xx
<CR><LF>
Start Verification
aV!
atttn <CR><LF>
Address Query
?!
a<CR><LF>
ClimaVUE 50 Compact Digital Weather Sensor 41
To Next Page
Loading...