Xylem H-339 - Manual (Page 14)

2-2 SDI-12 Command and Response Protocol
H-339
Example of a H-339 "aM!" command:
Command Response Time Values Description
------------- --------------------- ------- -------- -------------------------------
"aM!" "a2409" 240 sec 9 Get Time / Position Data
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
Measure Command
The Measure Command causes a measurement sequence to be performed. Data values generated
in response to this command are stored in the sensor's buffer for subsequent collection using "D"
commands. The data will be retained in the sensor until another "M", “C” or "V" command is
executed.
Command Response Description
-------------- ---------------------- ------------------------------------
"aM!" "atttn" Initiate measurement
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
M is an upper-case ASCII character
ttt is a three digit integer (000-999) specifying the maximum time, in seconds, the
sensor will take to complete the command and have measurement data available in
its buffer.
n is a single digit integer (0-9) specifying the number of values that will be placed in
the data buffer. If "n" is zero (0), no data will be available using
subsequent "D" commands.
Upon completion of the measurement, a service request "a" is sent to the data logger
indicating the data is ready. The data logger may wake the sensor with a break and collect the data
anytime after the service request is received or the specified processing time has elapsed.