Xylem H-3311 - Manual (Page 17)

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<cr><lf>”
Where:
a is the sensor address (“0-9”, “A-Z”, “a-z”, “*”, “?”). 15
SDI-12 Command & Response Protocol
Sensors that are able to continuously monitor the phenomena to be measured, such as a cable
position, 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-3301/3311 supports the aR0! continuous measurement command.
Continuous Measurements
example of an “ar0!” command:
Command Response
“aR0!” “a+X.XX+NNNN<cr><lf>
Where:
X.XX = Current position (stage), in user programmable units
NNNN = Current position (raw counts), in raw position counts
The “Continuous Measurement with CRC” command makes a measurement sequence with a CRC
appended to the data.
The H-3301/3311 supports the aRC0! continuous measurement command.
Continuous Measurements with CRC
example of an “arC0!” command:
Command Response
“aRC0!” “a+X.XX+NNNNYYY<cr><lf>
Where:
X.XX = Current position (stage), in user programmable units
NNNN = Current position (raw counts), in raw position counts
YYY = CRC (ASCII Characters)
Send Acknowledge Command