Xylem H-3551 - Manual (Page 25)

H-3551
SDI-12 Command and Response Protocol 5-7
5.5 Send Acknowledge Command
The Send Acknowledge Command returns a simple status response which includes the address of the sensor.
Any measurement data in the sensor's buffer is not disturbed.
Command Response
"a!" "a"
Where: a Is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
3.6 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 diagnostic
checksum tests. 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
Example of a "aV!" command:
Command Response Time Values Description
"aV!" "a0014" 1 sec 4 Return fixed data and diagnostic data for testing
purposes.
Subsequent Command Response
"aD0" a+123.456+78.9+x+y
Key Description Units
+123.456 Fixed test data
+78.9 Fixed test data
x Memory checksum 0-65535
y Checksum test “0” = Failed, “1” = Passed