| FPort  | LoRaWAN payload                                         |
+ ------ + --------------------------- + ------------------------- +
| RuleID | W     | FCN = b'1 |   RCS   |   Payload   | Opt padding |
+ ------ + ----- + --------- + ------- + ----------- + ----------- +
| 8 bits | 1 bit | 1 bit     | 32 bits | 6 to X bits | 0 to 7 bits |