Access Measurements
The global
measurements object allows you to access the device's current measurements. It is structured like this:{
"BATTERY": {
"field_name": "BATTERY",
"timestamp": "1600378287",
"value": 3.301
},
"SOIL_CONDUCTIVITY": {
"field_name": "SOIL_CONDUCTIVITY",
"timestamp": "1600378287",
"value": 121
}
}
function decoder() {
// get current value from field in Database
var field_in_db = measurements.FIELD_IN_DB.value;
}
If you want to build absolute counters you can use the database access on a decoder in order to read the currently stored value, add a new count and store back the new and updated count. We show you how you can do that.
function decoder(bytes, port) {
// relative change between messages will reset to zero with every sensor uplink
var relativeNumber = bytes[0];
// get current value from field in Database
var absoluteNumber = measurements["ABSOLUTE_CHANGE"].value;
// add relative change to absolute number
absoluteNumber = absoluteNumber + relativeNumber;
// store back absolute number
return [{
field: "ABSOLUTE_NUMBER",
value: absoluteNumber
}]
}
Last modified 10mo ago