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" Read current max (high) data setting
"aXRIL!" “a0011" Read current min (low) data setting
"aXWIHddd!" “a0011" Write max (high) data setting
"aXWILddd!" “a0011" 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" 1 sec 1 Read Max
Command Response Description
"aD0!" "a+50.0" Max is 50.0
Example of a H-4161 Extended Write High (max) command:
Command Response Time Values Description
"aXWIH1.234!" "a0011" 1 sec 1 Write Max
Command Response Description
"aD0!" "a+1.234" Max is 1.234