Xylem H-335 - Manual (Page 20)

2-4 SDI-12 Command and Response Protocol H-335
2.3 Concurrent Measure Command
This is a new command for the Version 1.2 SDI-12 Specification. A concurrent measurement is one which
occurs while other SDI-12 sensors on the bus are also taking measurements. This command is similar to the
“aM!” command, however, the nn field has an extra digit and the sensor does not issue a service request when
it has completed the measurement. Communicating with other sensors will NOT abort a concurrent
measurement. 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
"aC!" "atttnn" Initiate measurement
Where:
a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
C 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.
nn is a two digit integer (00-99) 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.
The data recorder may wake the sensor with a break and collect the data anytime after the specified processing
time has elapsed.