Codec for Dragino LHT65 and LDS02

Bovbjerg · April 22, 2024, 10:26am

I am struggeling with recieving data from these sensors. I have tried several codecs, but no one seems to work. They connects and uplinks OK, but I get the following error in the log:

level:“ERROR”
code:“UPLINK_CODEC”
description:“Exception generated by quickjs”

Does anybody have a working codec for these devices?

IoTThinks · April 23, 2024, 1:43am

It means your codec has Javascript error.

For LHT65N, you may try this codec.

github.com

IoTThinks/EasyLoRaWAN/blob/master/Codec/Dragino-LHT65N.js

// For firmware v1.3.2
// 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) {
    return {
        data: Decode(input.fPort, input.bytes, input.variables)
    };
}

function str_pad(byte) {
    var zero = '00';
    var hex = byte.toString(16);
    var tmp = 2 - hex.length;

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IoTThinks · April 23, 2024, 1:46am

For LDS02, try this.

github.com

dragino/dragino-end-node-decoder/blob/main/LDS02/lds01_02_Decoder_Chirpstack_V4_v1.5.txt

function decodeUplink(input) {
        return { 
            data: Decode(input.fPort, input.bytes, input.variables)
        };   
}
function Decode(fPort, bytes, variables) {
  // Decode an uplink message from a buffer
  // (array) of bytes to an object of fields.
  var value=(bytes[0]<<8 | bytes[1])&0x3FFF;
  var bat=value/1000;//Battery,units:V
  
  var door_open_status=bytes[0]&0x80?1:0;//1:open,0:close
  var water_leak_status=bytes[0]&0x40?1:0;
  
  var mod=bytes[2];
  var alarm=bytes[9]&0x01;
  
  if(mod==1){
    var open_times=bytes[3]<<16 | bytes[4]<<8 | bytes[5];
    var open_duration=bytes[6]<<16 | bytes[7]<<8 | bytes[8];//units:min

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Bovbjerg · April 23, 2024, 9:00am

Thankyou very much. This codec works.

Bovbjerg · April 24, 2024, 5:37pm

Hi again
The codec for lht65 vorks fine, but the codec for lds02 does not. I get the following error:
Details: 2024-04-24 18:07:50

Download

- time:“2024-04-24T16:07:50.626317280+00:00”

deviceInfo:{} 10 keys
* tenantId:“52f14cd4-c6f1-4fbd-8f87-4025e1d49242”
* tenantName:“ChirpStack”
* applicationId:“e13195f2-dd3c-46c6-95b0-a1c1f636b0b0”
* applicationName:“Dragino door sensors”
* deviceProfileId:“872f981e-c2cd-44e0-88e9-839e9e021021”
* deviceProfileName:“Dragino door sensors”
* deviceName:“Toiletdør”
* devEui:“a84041e781830ccc”
* deviceClassEnabled:“CLASS_A”
* tags:{} 0 keys

level:“ERROR”
code:“UPLINK_CODEC”
description:“Exception generated by quickjs”

context:{} 1 key
* deduplication_id:“fcb0ebfe-8ae4-4f2a-bf14-0fb3f60a82a5”

IoTThinks · April 25, 2024, 2:57am

What is the version of your ChirpStack?
ChirpStack v4.7 should show more detail of the error.

The codec for LDS02 looks correct to me.
However, I don’t have the LDS02 to test.
Please show your Data in hex so I can check in free time.

Bovbjerg · April 25, 2024, 9:31am

Hi there, thanks for your help.
I am running a RAK2744 on a Raspberry Pi Zero W and the Firmvare is ChirpStack Gateway OS 4.3.2 Full. This is the latest on the download page for Raspberry Pi.

My data is data:“DEIBAAABAAAAAA==”

I is very strange, because the Codec for my LHT65 worked fine for a while but now it gives the same error again. The only change I made was a reboot.

My data for the LHT65 is * data:“ywEE+AJeAQMyf/8=”

IoTThinks · April 25, 2024, 10:45am

A picture worths a thoudsand words.

Bovbjerg · April 25, 2024, 3:38pm

For the LDS02

And for the LHT65

IoTThinks · April 26, 2024, 3:06am

You capture an incorrect packet for LDS02 as I can see the fport=0
fPort=0 means MAC commands not uplinks.
Check for those with fport >0
And check in the Events tab.

Choose Javascript functions

The packet for LHT65N is correct.
The codec should work.
Generally, I want the whole list of packets to debug.
Just like in the picture.

Bovbjerg · April 26, 2024, 1:18pm

Thank you for your help in this. As you confirmed, the Codecs were working, the fault must have been elsewhere, so I flashed a new SD cars, and now everithing works .