Appendix C. CS700H Operation Details
C-8
C.6.2.1 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.
C.6.2.2 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
).
C.6.2.3 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
n
= the number of values to be returned when one or more subsequent
D!
commands are issued
C.6.2.4 Address Query Command (?!)
Command
?!
requests the address of the connected sensor. The sensor replies
to the query with the address,
a
. This command should only be used with one
sensor on the SDI-12 bus at a time.
C.6.2.5 Change Address Command (aAb!)
Multiple SDI-12 sensors can connect to a single SDI-12 terminal on a data
logger. Each device on a single terminal must have a unique address.
