Xylem H-4161 - Manual (Page 27)

H-4161
SDI-12 Command and Response Protocol 3-11
3.11 Extended Read/Write Max (High) and Read/Write Min (Low)
The H-4161 processes the captured SDI-12 data with a linear mx+b equation to scale the data
into values between 4.0 and 20.00 suitable for the 4-20mA output. The slope(m) and offset(b)
terms are automatically computed using user programmable Max and Min settings. This makes it
easy to scale the measurement data into the proper 4-20mA output. These four commands allow
the user to read or write the current Max or Min settings. The settings are stored in non-volatile
Flash memory. Once the new Max or Min value is written to the Flash memory, a copy is sent to
the sensor data buffer for verification. This data can be viewed by using a subsequent "D"
command. To verify these settings any other time, use the "XRIH" or “XRIL” commands. This
command takes 1 second to complete and places 1 value in the data buffer.
Command Response Description
"aXRIH!" “a0011<cr><lf>" Read current max (high) data setting
"aXRIL!" “a0011<cr><lf>" Read current min (low) data setting
"aXWIHddd!" “a0011<cr><lf>" Write max (high) data setting
"aXWILddd!" “a0011<cr><lf>" Write min (low) data setting
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
XRIH are upper case characters.
XRIL are upper case characters.
XWIH are upper case characters.
XWIL are upper case characters.
ddd is the new max or min value (For example: 20.0, 195)
Example of a H-4161 Extended Read High (max) command:
Command Response Time Values Description
"aXRIH!" "a0011<cr><lf>" 1 sec 1 Read Max
Command Response Description
"aD0!" "a+50.0<cr><lf>" Max is 50.0
Example of a H-4161 Extended Write High (max) command:
Command Response Time Values Description
"aXWIH1.234!" "a0011<cr><lf>" 1 sec 1 Write Max
Command Response Description
"aD0!" "a+1.234<cr><lf>" Max is 1.234