Parsing hexadecimal payload into GPS coordinates

agenis

I'm trying to parse a payload received in the message from a Sigfox tracker. The payload is a hexadecimal number stored as a string. Here is an example of the message parsed by the channel:

{
  "ident": "21FC98",
  "deviceType": "XXXX",
  "time": "1655797254",
  "data": "01000108000052aa0000ff8d"
}

I created, as seen in a flespi tutorial, a PVM plugin to treat this data:

.data ==> %hex ==> bits:
	8 ==> skip // skip first byte
	16 ==> #firmwareversion

However, I get the following plugin processing error:
error_text : "000048 [plugin.726029.1021549:1:11] in @import.plugin_code: {ext} not a hex number: '01000108000052aa0000ff8f'"

How can I solve this error? Thanks,

namo

Hello agenis ,
The string "01000108000052aa0000ff8d" is too big to fit into an integer.
Please take a look at the code below - it brakes the data parameter into three hexadecimal strings that are converted into the three 32bit integer parameters.

// "data": "01000108000052aa0000ff8d"
.data[string] ==> input:
	[size=8] ==> %text ==> %hex ==> #param.first // 0x01000108
	[size=8] ==> %text ==> %hex ==> #param.second // 0x000052aa
	%text ==> %hex ==> #param.third // 0x0000ff8d

If you need more help on this matter, please provide more details how you want to parse data parameter, and we will try to help you.

kial

agenis, using ==> %hex you're decoding a string into a 64-bit (8-bytes) number encoded as a HEX.
But you have a 24-chars-long string which is not fit in 8 bytes after decoding, so you have an error that your string is not a valid hex number.

The way namo mentioned will also work but it's better to parse data from HEX string only once and then follow the binary structure/encoding of your data transparently transferred by Sigfox. Here is how to do it:

// 24-char string "01000108000052aa0000ff8f" decoded as hex string into a 12-bytes binary data on input:
.data ==> %hexstr ==> input:
	%uint8 ==> skip					// 0x01 skipped
	%uint16 ==> #firmware.version	// 256 == 0x0100 parsed into a parameter
	// and rest of the data are skipped

In the input: section you're dealing with binary data, no more with json message with properties. And you can use other integer sizes like %uint32 ==> ... or %int32 ==> ... to parse data accordingly or even change endianness with %uint16[BIG] ==> ...