Every value has a fixed lenght.
Al not used values have to be filled with zero's
Your pc is using big endian, the sodaq one and almost all microcontrollers use litteendian.
If the defined lenght is longer then one byte, you need to change the order.
12 34 -> 34 12
12 34 56 78 -> 78 56 34 12
sample interval: 15 minutes
altenetive interval: we don;t want to set it
gps timeout: 120 seconds
15 minutes to hex -> 0F
defined lenght is uint16 -> 00 0F
endian swap -> 0F 00
All values together will result in:
I hope this helps you a bit.