Xylem H-3531 FlashLite - Manual (Page 42)

5-4 SDI-12 Command and Response Protocol
H-3531
5.2 Measure H-355 Gas Purge System
This Measure Command causes a new measurement sequence to be executed in the H-355 Gas
purge system. The Data values generated are the Tank and Line PSI as well as the difference.
Data values 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
"aM2!" "atttn" Measure H-355 Tank and Line PSI
Where:
a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
M 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.
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.
Upon completion of the measurement, a service request "a" is sent to the data recorder
indicating the sensor data is ready. The data recorder may wake the sensor with a break and
collect the data any time after the service request is received or the specified processing time has
elapsed.
Example of a H-3531 "aM2!" command:
Command
Response Time Values Description
"aM2!" "a0053" 5 sec 3 Make measurement
Subsequent Command Response
"aD0" a+AA.A+BB.B+CC.C
Where:
AA.A = Tank Pressure (PSI)
BB.B = Line Pressure (PSI)
CC.C = Difference between Tank and Line (PSI)