Table B-1: Campbell Scientific sensor SDI-12 command and response sets
Name
1
Command
Response
Start verification
aV!
atttn <CR><LF>
Address query
?!
a<CR><LF>
Change address
aAb!
b<CR><LF>
Start measurement
aM!
aM1!...aM9!
atttn<CR><LF>
Start concurrent
measurement
aC!
aC1!...aC9!
atttnn<CR><LF>
Send data
aD0!...aD9!
a<values><CR><LF> or
a<values><CRC><CR><LF>
Continuous measurement
aR0!...aR9!
a<values><CR><LF>
1
Information on each of these commands is given in the following sections.
B.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.
B.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. Source:
SDI-12: A Serial-Digital Interface Standard for Microprocessor-Based Sensors
(see
[p. 29]).
Command:
aI!
Response:
allccccccccmmmmmmvvvxxx...xx<CR><LF>
Where
a
= sensor address
ll
= SDI-12 version number (indicates compatibility)
cccccccc
= 8-character vendor identification
vvv
= 3 characters specifying the sensor version (operating system)
TempVue 20 SDI-12 PT-100 Class A, Precision Air Temperature Sensor
21
