i m retrieving temperature value from dht22 to a function node in msg.payload. how to turn something On or Off based on temperature value? help would be much appriciated.
Use a debug node to understand your data, this page in the docs is a key doc to read https://nodered.org/docs/user-guide/messages
Then investigate the
switch node to separate messages.
How to turn something on /off well that will depend on what the something is, but I'm sure looking at flows.nodered.org the cookbook.nodered.org and http://noderedguide.com you should be able to get started.
PS, this should really be asked in #general as you aren't developing the Node-RED code...
temperature value is in payload when attached debug node. something connected to raspberry gpio pin. what should be the code in function node. i tried if else but it wont return Boolean.
You don't need a function node.
If your data is msg.payload you could use a switch to only allow through the values you want and then a change node.
Alternatively post your code and what the data see in the debug...
thats what i have done so far. in function node its just msg.payload=msg.payload; return msg;
debug shows: 16/07/2019, 13:04:20node: ff5af76a.59b928rpi-dht22 : msg.payload : string
16/07/2019, 13:04:20node: 4c3eb789.797c58rpi-dht22 : msg.payload : string
So you didn't post the contents of your function node which does make it more difficult
But I'm guessing it's because you're msg.payload is a string not a number.