Xylem H-340SDI - Manual (Page 19)

H-340SDI
SDI-12 Command and Response Protocol 2-5
Example of a H-340SDI "aD0!" command:
Previous command Response
----------------------- ------------------------------------------
"aM!" "a0015"
Subsequent Command Response
--------------------------- ------------------------------------
"aD0" a+AA.AAA+BB+CC.CCC+DD.DDD+EE.EEE
Where:
AA.AAA = Rainfall accumulation since last measurement (inches of rain)
BB = Number of bucket tips since last measurement (raw count)
CC.CCC = Total accumulation since reset (inches of rain)
DD.DDD = Total accumulation today (inches of rain)
EE.EEE = Total accumulation yesterday (inches of rain)
2.5 Continuous Measurements
This is a new command for the Version 1.2 SDI-12 Specification. Sensors that are able to
continuously monitor the phenomena to be measured, such as a cable, do not require a start
measurement command. They can be read directly with the R commands (R0!...R9!). The R
commands work exactly like the D (D0!...D9!) commands. The only difference is that the R
commands do not need to be preceded with an M command.
The H-340SDI DOES NOT supports the aR0! continuous measurement command.
2.6 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", "*", "?").