User guide

5-18 SDI-12 Command and Response Protocol H-3521
5.16 Extended Read/Write NOAA Mode Enable
The H-3521 can be put into a NOAA Mode. In NOAA mode the data collection platform requests
data from the H-3521 every second for 3 minutes and then is idle for 3 minutes. When NOAA
Mode is enabled the H-3521 measurement response time is less than 1 second. Meaning that the
Data command can be sent within 1 second after the measure command is issued. When the
enable value is set to a ‘1' the NOAA Mode is enabled and when it is set to a ‘0' NOAA Mode is
disabled.
Command Response Description
“aXRNE!” “a0011<cr><lf>” Read NOAA Mode enable
“aXWNEd!” “a0061<cr><lf>” Write NOAA Mode enable
Where: a is the sensor address ("0-9", "A-Z", "a-z", "*", "?").
XRNE are upper case characters.
XWNE are upper case characters.
d is the new enable value (0=disabled, 1=enabled)
When the user enables NOAA Mode it takes 6 seconds because it updates the Atmospheric and
Temperature values until the 3 minute no activity gap.
Example of a H-3521 Extended "Read NOAA Mode Enable" command:
Command Response Time Values Description
"aXRNE!" "a0011<cr><lf>" 1 sec 1 Read NOAA Mode Enable
Command Response Description
"aD0!" "a+0<cr><lf>" NOAA Mode disabled
Example of a H-3521 Extended "Write NOAA Mode Enable" command:
Command Response Time Values Description
"aXWNE1!" "a0061<cr><lf>" 6 sec 1 Enable NOAA Mode
Command Response Description
"aD0!" "a+1<cr><lf>" NOAA Mode enabled
Example of a H-3521 "aM!" command in NOAA Mode:
Command Response Time Values Description
"aM!" "a0011<cr><lf>" 1 sec 1 Measure in NOAA Mode
Command Response Description
"aD0!" "a+AA.AA<cr><lf>" Returns Stage