RDR-N Payload Description (DRAFT)

This document describes the Payload of the Parametric ReorderDirect™ NFC Reader with LoRaWAN™

General Information

RDR devices are sending the memory content of RFID Tags without any modification. Due to the limitations of LoRaWAN™, scanned data needs to be buffered and timestamped in a FIFO (first in, first out) style buffer.

LoRaWAN™ limitations include:

  • air time restrictions for EU868 regions (ETSI)
  • carrier restrictions (max number of uplinks/downlinks per day)
  • “fair use policies” when using TTN. Parametric recommends using Loriot.io Networks.

Scan Record Data Structure

The LoRaWAN™ payload is generated by appending one or more scan records, delimited by the form feed escape command 0x0C. Payload length depends on the length of all scan records.

PCR2 Function Demonstration

Scan Records vs LoRaWAN™ Payload Length

When the buffer contains more than one scan record, the device will pack as many scan records into the LoRaWAN™ payload as possible. The firmware takes care to not exceed the max LoRaWAN™ payload length allowed in the current situation.

Data Rate Maximum LoRaWAN™ payload size allowed
air time limits
Scan record size
NDEF Payload “Hello”
Max Scan Records per Uplink
0 59 24 2
1 59 24 2
2 59 24 2
3 123 24 5
4 230 24 9
5 230 24 9
6 230 24 9
7 230 24 9

RDR-N uses the automatic data rate adaption (ADR) function. Nevertheless HF performance can not be guaranteed when using LoRaWAN™ networks. It’s therefore a good idea to go expect the worst case.

See LoRaWAN™ 1.0.2 Regional Parameters Document for more information.

LoRaWAN Application Payload Format

Byte Property Description Data Range (Hexstring) Example
0:5 Timestamp Timestamp
125F33D83340-5AF105D18777 20201010125823
10th October 2020, 12:58:23
6:13 NFC_Serial NFC Serial Number 0000000000000000-FFFFFFFFFFFFFFFF 93441232009ABEFF
14 NDEF_Record_ID NDEF File Id
Always 0 on RDR-N devices
00-00 00
NDEF File 0
15 NDEF_Record_Length Length of NDEF Payload 00-28 05
16 NDEF_Record_Type Type of NDEF Data 00-0C 09
Text Type
17:nn NDEF_Payload NDEF File Data
40 bytes max.
0-40 bytes 48 65 6C 6C 6F
nn+1 EOSR End of Scan Record 0C 0C

Examples (Hexstring)

NFC-Tag with S/N 93441232009ABEFF containing NDEF Text File, “Hello”

20 20 10 10 12 58 23 93 44 12 32 00 9A BE FF 00 05 09 48 65 6C 6C 6F 0C

Ports used

Uplink Port 18