Xylem H-339 - Manual (Page 17)

H-339
SDI-12 Command and Response Protocol 2-5
Example of a H-339 "aV!" command:
Command Response Time Values Description
------------- --------------------- ------- -------- ---------------------------
"aV!" "a0013" 1 sec 3 Return fixed data and diagnostic
data for testing purposes.
Subsequent Command Response
--------------------------- --------------------------------------------
"aD0" a+123.456+78.9+y
Key Description Units
------------- ------------------------- ----------------------------
+123.456 Fixed test data
+78.9 Fixed test data
y ROM checksum test 0 = Failed, 1 = Passed
Initiate Verify Command
The Verify Command causes a verify sequence to be performed. The result of this command is
similar to the "aM!" command except that the values generated are fixed test data and the results of
a diagnostic checksum test. The data generated in response to this command is placed 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
------------- ------------------------- ---------------------------
"aV!" "atttn" Initiate verify sequence
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
V 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 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.