Xylem H-4161 - Manual (Page 22)

3-6 SDI-12 Command and Response Protocol
H-4161
3.4 Send Data Command
The Send Data command returns sensor data generated as the result of previous "aM!", "aC!", or
"aV!" commands. Values returned will be sent in 33 characters or less. The sensor's data buffer
will not be altered by this command.
Command Response
"aD0!" "apd.d<cr><lf>"
Where:
a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
D0 are upper-case ASCII characters.
p Is a polarity sign (+ or -)
d.d represents numeric digits before and/or after the decimal. A decimal may be used
in any position in the value after the polarity sign. If a decimal is not used, it will
be assumed to be after the last digit.
For example: +3.29 +23.5 -25.45 +300
If the "aD0!" returns no data (“a<cr><lf>” only), it means that no measurement data is available
(or the measurement was aborted) and a new "M" command must be sent. If the module mode is
“MONITOR”, an “a<cr><lf>” response indicates no measurement has been captured. If the
module mode is “INITIATE”, an “a<cr><lf>” response indicates the most recent measurement on
the AuxSDI port has failed.
Example of a H-4161 "aD0!" command:
Previous Command
Response
"aM!" "a0001<cr><lf>"
Subsequent Command Response
"aD0" a+AA.AAA<cr><lf>
Where:
AA.AAA = Most recent measurement (feet, inches, meters etc.)