Xylem H-4280 - Manual (Page 30)

3-18 SDI-12 Command and Response Protocol H-4280
3.14 Extended Read Warmup_Time and Write Warmup_Time
The H-4280 has a precision +5Vref excitation output terminal for powering potentiometers,
thermistors and other sensors. The +5Vref output is normally turned off to save power while the
module is in its sleep mode and is switched on before a measurement is made. The
Warmup_Time is a programmable delay (1 to 999 seconds) which elapses before the first
measurement is made. Use the “aXRWT!” and “aXWWT!” extended commands to monitor or
change the warmup (wake up) time.
Once a new Warmup_Time value is written, a copy is sent to the sensor data buffer for
verification. This data can be viewed by using a subsequent "D" command. To read or verify the
value any other time, use the "XRWT" command. Do not set Warmup_Time to zero.
Command Response Description
"aXRWT!" “a0011"
Read Warmup_Time
"aXWWTnnn!" “a0011" Write Warmup_Time
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
XRWT are upper case characters.
XWWT are upper case characters.
nnnn number of seconds
This command takes 001 seconds to complete and places 1 value in the data buffer. Use the
“aD0" command to collect and view the current value.
Example of a H-4280 Extended "Read Warmup_Time" command:
Command Response Time Values Description
"aXRWT!" "a0011" 1 sec 1 Read Warmup_Time
Command Response Description
"aD0!" "a+1" Warmup_Time is 1.0 seconds
Example of a H-4280 Extended "Write Warmup_Time" command:
Command Response Time Values Description
"aXWWT10!" "a0011" 1 sec 1 Write Warmup_Time
Command Response Description
"aD0!" "a+10" Warmup_Time time is 10 seconds