H-339 – Xylem H-339 User Manual
Page 16
2-4 SDI-12 Command and Response Protocol
H-339
Example of a H-339 "aD0!" command:
Previous command
Response
-----------------------
------------------------------------------
"aM!"
"a0022
Subsequent Command
Response
--------------------------- ------------------------------------
"aD0"
a+ss+mm+hh+DD+MM+YY
"aD1"
a+DDMM.mmmm+DDDMM.mmmm+F
Where:
ss = Seconds, mm = Minutes hh = Hours DD = Date MM = Month YY = Year
DDMM.mmmm = Latitude DDDMM.mmmm = Longitude F = Pass / Fail Flag
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!" through "aD9!"
"apd.d ... pd.d
Where: a
is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
D0..D9
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 number of values returned by a "aD0!" command is less than the number specified by the result
of the previous "M" or "V" command, the rest of the data must be collected using "aD1", "aD2!"
.... "aD9!" until all values specified have been collected. If one or more values were specified and
a "aD0!" returns no data (a
"M" command must be sent. The following is an example of the "aD0!" and “aD1!” supported by
the H-339.