Where can I find a description of a ChirpStack v4 data packet from an end node?
I have an Arduino MKRWAN 1310 and have not been successful in getting data from it into ChirpStack or NodeRed. I can see the Payload Raw data bytes but cannot find how to process them into meaningful values.
This site has instructions on creating a codec but it does not seem to be working for me: Create a codec for LoRaWAN Nodes - IoTThinks.com
This is your DIY LoRaWAN node.
So you are the one who decide the format of the uplink payload.
What is the message / payload are you trying to send?
Is it a text/string or something?
Could you screenshot the code of your sending message?
Show me your code of the upload part.
I can give you the sample decode.
I guess you are uploading a string like “Hello”?
I added a converter from bytes array to a string for you.
This is a decoder to decode a string payload in an uplink.
function decodeUplink(input) {
var bytes = input.bytes;
// To convert a byte array bytes to a string returnStr
// To remove a null character at the end
var returnStr = String.fromCharCode.apply(String, bytes ).replace(/\0/g,'');
return {"data": {"returnStr ":returnStr}};
}
You need to create a decoder (codec in chirpstack naming scheme) and then feed the data to a integration.
Can you post your decoder?
Thank you all for your help. I am using the example program that comes with the Arduino MKRWAN library: LoraSendAndReceive.ino. All it does is connect and allow the user to enter a text string to send. Using the codec from IoTThinks, all I see using NodeRed is returnStr : “”. However, in Chirpstack LoRaWAN frames I can see the decimal values of the characters in frm_payload: Raw.
LoRaWAN is NOT for strings. LoRaWAN is for couple of bytes. To my style no more than 10-15 bytes. Strings are bad practice. Use numbers: bytes, not characters.
Use bytes and then feed them with the decoder to an integration. In fact in Chirpstack for a rough view, you can skip the integration. You can go Device profile > Measurements and if your decoder is working fine you can define in Measurements the variables.
After that for Applications > Device > Select Device > Device metrics you can see your decoded data.
Find a way to test your decoder. Chirpstack does not have a tool to help you for this.
Hi clavisound, I realize that LoRaWAN is for short bursts of data. Right now I am just trying to see if the codec gets the bytes being sent. So far I have not been successful.
You need to share the screenshots to get help.
For the data, you need to look at Events tab, not LoRaWAN Frames tab.
Start simple. Send one byte - for example battery level - and then decoded it with the coder. In events tab you will see the decoded value not only the encrypted. Configure the node to send every time you press the button or periodically to debug.
Example for one byte - untested
// Decode uplink function.
//
// Input is an object with the following fields:
// - bytes = Byte array containing the uplink payload, e.g. [255, 230, 255, 0]
// - fPort = Uplink fPort.
// - variables = Object containing the configured device variables.
//
// Output must be an object with the following fields:
// - data = Object representing the decoded payload.
function decodeUplink(input) {
var data = {};
data.battery = input.bytes[0];
return {
data: data
};
}
I believe I have not made myself clear. The data which is shown looking at the Events tag are AFTER the codec. The frames tag does show the four bytes I entered into the MKRWAN 1310 in a section named Payload Raw. I have tried displaying the individual bytes within input.bytes and get all 0s. I have also put fixed values into input.bytes in the codec and they get accepted and displayed within both Node Red and ChirpStack.
So, it looks to me like the codec is either not getting the bytes or there is another object I need to try.
Post your decoder. Maybe you made yourself clear but I don’t understand you.
It’s the third time that we ask for the decoder to help you.
Sorry to be so late with this, had some sickness last week.
Here are two versions of decoders I have tried. I am using the Arduino sample program LoraSendAndRecieve.ino to send data to LoRaWAN. For both tests I sent a single byte value of “1” which is a decimal value of 49.
function decodeUplink(input) {
// this works as expected when I send something from the 1310
var Humid = 511;
var Temp = 213;
var VBat = 3006;
return {“data”: { “Humid”:Humid, “Temp”:Temp, “Vbatt”: VBat } };
}
Looking at the Event, I show
object: {} 3 keys
Temp: 213
Vbatt: 3006
Humid: 511
function decodeUplink(input) {
// this does not work: Humid shows a value of null, Temp and Batt are correct
var Humid = input.bytes[0] + input.bytes[1] + input.bytes[2] + input.bytes[3] + input.bytes[4];
var Temp = 213;
var VBat = 3006;
return {“data”: { “Humid”:Humid, “Temp”:Temp, “Vbatt”: VBat } };
}
Looking at the Event, I show
object: {} 3 keys
Humid: null
Vbatt: 3006
Temp: 213
Show us the payload you send in your Arduino program.
How you send will define how you need to decode.
This is hardcoded value. So it has not much value for this test.
This is not correct in most cases.
However, we need to know how you send data (in which format) to have a correct decoder.
You may want to give us your screenshot of this page
So we can know what kind of data are you uploading.
This is wrong as @IoTThinks writes.
Now we also need the code from the node.
This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.
