Campbell CS650, User Manual

Page: 52 / 56

Appendix D. SDI-12 Sensor Support
D-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.
An example of a response from the aI! command is:
313CampbellCS65X 000Std.00.35=2196405 <CR><LF>
where:
Address = 3
SDI-12 version =1.3
Manufacturer = Campbell
Sensor model = CS65X
OS version = 000Std.00.35
Sensor serial number = 2196405
Start Measurement Commands (aM!)
A measurement is initiated with M! commands. The response to each command
has the form atttnn, where
a = sensor address
ttt = time, in seconds, until measurement data are available
nn = the number of values to be returned when one or more subsequent D!
commands are issued.
Start Measurement Command (aMv!)
Qualifier v is a variable between 1 and 3 that requests variant data. Variants
include different subsets of the CS650 probe output:
M0! Volumetric Water Content (

Bulk Electrical Conductivity
(

Temperature (°C)
M1! Permittivity (

Bulk Electrical Conductivity (

Temperature (°C)
M2! Period (

Voltage Ratio (

Temperature (°C)
M3! Volumetric Water Content (

), Bulk Electrical Conductivity
(

Temperature (°C), Permittivity (

Period (

Voltage Ratio (

Aborting a Measurement Command
A measurement command ( M! ) is aborted when any other valid command is sent
to the sensor.
Send Data Command (aDv!)
This command requests data from the sensor. It is normally issued automatically
by the datalogger after measurement commands
aMv! . In transparent mode, the
user asserts this command to obtain data. If the expected number of data values
are not returned in response to an
aD0! command, the data logger issues aD1! .
The limiting constraint is that the total number of characters that can be returned