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Generic NFC and downlink documentation

Are you looking for generic NFC and downlink documentation or wondering how to interpret certain parameters and values for activation?

Downlink Documentation (Generic) – HTML
📄 You can view the PDF above or download it here .

1. Version History

Version Date Revision
1.0.0 January 6, 2023 Created
1.0.1 April 9, 2026 Structure standardized
Downlink clarified
Content updated

2. Downlinks

This documentation can be used for all sensors in the Sentinum series that support NFC and downlink functions. It serves as generic documentation. Individual descriptions of the fields can be found in the respective sensor-specific documentation.

All downlinks for the sensor and LoRa module are terminated on Port 4. All commands that execute a function, such as resets, are terminated on Port 5.

Like the payload, the downlink commands are also divided into modules. The sensor merely acts as a container that manages and executes the commands. The downlinks can be used to configure the sensor for the respective application. In addition to configurations, executable downlinks such as a reset can also be performed. All commands are protected by minimum and maximum values.

Hierarchical structure:
  • Module
  • Group
  • Resource
  • Command

A module has several groups, which in turn consist of several resources.

3. Overview of the ports for the downlink

Port Channel Description
0 Uplink Join
1 Uplink Telemetry Uplink
2 Uplink Information Uplink
3 Uplink Response to a downlink
4 Downlink Port for downlinks to configure settings
5 Downlink All commands marked with EXEC, e.g., Supervisor Module, Reboot, Reset, or Start Scan
6 Downlink Downlink command for reading configurations
192 Uplink GNSS scan data
197 Uplink Wi-Fi SSID scan data
Mnemonic: Port 4 for configuration, Port 5 for executable commands, Port 6 for reading current configurations.

4. Modules and Groups – Example Overview

Module Module Key Group Group ID Description
Juno 0x1XXX Alarm Settings & Timing 0x00 Defines parameters for alarm settings, measurements, and transmission behavior
Juno 0x1XXX ToF Sensor Settings 0x01 Defines measurement parameters for the ToF sensor
Juno 0x1XXX Radar Sensor Settings 0x02 Defines measurement parameters for the radar sensor
Juno 0x1XXX Opening Detection Settings 0x03 Defines measurement parameters for the opening counter
Juno 0x1XXX Vandal Detection Settings 0x04 Defines measurement parameters for vandalism detection
LoRa 0x2XX1 Network Settings 0x00 Network Management Settings
LoRa 0x2XX1 Transmission Settings 0x01 Transmission Parameters and Protocol Settings
LoRa 0x2XX1 Rejoin Settings 0x02 Parameters for Link Check

5. Important points regarding downlinks

  • All configuration commands for sensor and LoRa modules are executed on port 4, all execution commands on port 5.
  • Sentinum guarantees backward compatibility across different subversions. A Sentiface/Sensor module with the key 0x1121 also accepts downlink commands with the key 0x1111.
  • The actual value communicated to the sensor via downlink is always 4 bytes, except for command messages (executables). In those cases, the message size varies.
  • A downlink is always acknowledged with an additional uplink as a response.
  • Starting with version 0x22XX, current parameters can be queried via downlink. No configuration value is sent along with this. The downlink must be sent on port 6; the response is sent on port 3.
Example for reading the current ADR value:
11 22 11 01 02

6. Structure of the module key

Structure of the module key

Byte Bit range Meaning
Byte 1 Bits 7–4 Base ID, e.g., Sensor, LoRa, or Sentivisor
Byte 1 Bits 3–0 Major version (SW/HW version)
Byte 2 Bits 7–4 Minor version (SW/HW version)
Byte 2 Bits 3–0 Product version (mounted sensors)

The module key of the sensor module can be derived from the first two bytes of each uplink.

  • The module key explained here applies only to the sensor module. For the LoRa module, always use 0x2XXX as the module key.
  • In addition to the downlinks, there is an app for the initial configuration of the sensor. The NFC interface offers additional configuration options, such as for APPEUI or APPKEY.

General downlink structure

Byte Designation Description
Byte 0 Token Used to assign a confirmation to a previously sent command. Can be freely chosen.
Bytes 1 to 2 Module key Describes the specific version of the sensor and selects the module.
Byte 3 Group Selects the group to which the command is assigned.
Byte 4 Resource Selects the resource ID within the group.
Bytes 5 through 8 Value Contains the new resource value. 
Example downlink:
0x01 0x1111 0x03 0x00 0x00 00 10 00

7. Commands to Execute – Executables

Downlink commands can be scheduled in the network server. These do not have a configurable value, meaning the last four bytes for value setting are omitted. Executable commands are assigned to the respective groups.

The following example simplifies the GNSS group of a Juno sensor.

Resource Resource ID Description Module Key
GNSS MODE 0x00 Order of localization technologies: 0 Off, 1 GNSS Scan, 2 Wi-Fi SSID Scan, 3 GNSS then Wi-Fi, 4 Wi-Fi then GNSS 22XX
GNSS UPDATE PERIOD 0x01 Localization update period in hours 22XX
DOWNLOAD ALMANAC DATA 0x02 0: Do not download data, 1: Download almanac data 22XX
GNSS IN MOBILE APPLICATIONS 0x03 0: optimized for static objects, 1: optimized for moving objects 22XX
PERFORM SCAN 0x04 Start scan. Example downlink on port 5: 11 2211 03 04 22XX

8. Glossary for the Documentation

Term Explanation
Group ID An ID that allows the user to modify various resources within a configuration unit.
Resources Individual modifiable elements responsible for the configuration and customization of a system.
Resource ID An identifier that distinguishes between different configuration options of a system.
Key An NFC/BLE key for authentication and access control to resources within a system.
Min / Max Minimum / Maximum
Module Key A key that enables access to a specific configuration unit within a system.

Additional Glossary

Term Explanation
green / yellow / red The focus is not on color accuracy, but on the variety of shades of green/orange, yellow, and amber/red tones, although the colors may vary depending on the product.
Default (old) Used as a synonym for factory setting.

9. Sensor Settings – Apollon-Q Example

9.1. Sensor: Timings and Alarms Group 0x00

Resource Resource ID Description Min Max Default Unit Module key
MEASUREMENT PERIOD 0x00 Sets the time period during which measurement values are recorded. 5 660 60 1111
DELTA VALUE 0x01 Absolute value by which the level must change since the last transmission in order to trigger an alarm transmission. 30 2000 200 1111
TRANSMISSION INTERVAL 0x02 Number of measurements after which the sensor schedules an uplink despite the absence of an alarm condition. 1 10 1 dr 1111
MASTER VALUE 0x03 Specifies which sensor value is written to the master_value parameter: 0 ToF, 1 Radar. 0 1 0 1111

9.2. Sensor: ToF Sensor Settings Group 0x01

Resource Resource ID Description Min Max Default Unit Module Key
ToF RANGING MODE 0x00 0 automatic, 1 fixed. In automatic mode, the sensor selects between short, medium, and long. 0 1 0 1111
ToF RANGE INDEX 0x01 0 short, 1 medium, 2 long. 0 2 1 1111
ALGORITHM APPLIED 0x02 0 No histogram, 1 Histogram, 2 Hybrid. 0 2 2 1111

9.3. Sensor: Opening Detection Group 0x03

Resource Resource ID Description Min Max Default Unit Module Key
OPENING DETECTION COOLDOWN 0x00 Time period during which no further opening can be triggered after an opening has been triggered. 1 600 120 1111
OPENING DETECTION ALARM AFTER 0x01 Time the cover must remain open before an alarm is triggered. 60 3600 900 1111
OPENING DETECTION SOURCE 0x02 0 None, 1 Accelerometer, 2 Hall Switch. 0 2 0 1111
OPENING DETECTION HALL SWITCH 0x03 0 Container closed when solenoid is activated, 1 Container open, 2 Sensor detects an opening when the sensor is triggered twice. 0 2 0 1111
OPENING DETECTION ACTIVE 0x04 0 disabled, 1 enabled. 0 1 0 1111
OPENED LID OR FLAP 0x05 Specifies whether an alarm is triggered after the "Open Alarm After" time has elapsed if the container is open. 0 1 0 1111

9.4. Sensor: Vandalism Detection Group 0x04

Resource Resource ID Description Min Max Default Unit Module Key
VANDALISM DETECTION ACTIVATED 0x00 0 Vandalism detection off, 1 Vandalism detection on. 0 1 0 1111
IMPACT DELTA 0x01 Maximum time between two impacts for a vandalism alarm to be triggered based on the number of impacts. 5 100 30 sec 1111
IMPACT NUMBER 0x02 Number of impacts, of which no more than two may fall within Impact Delta. 3 100 5 1111
IMPACT STRENGTH 0x03 A hit is counted when the acceleration exceeds the set impact strength value. 500 2000 1000 Mg 1111
COOLDOWN 0x04 The time period during which no further vandalism alarm can be triggered after a vandalism alarm has been triggered. 10 1440 30 min 1111

9.5. Sensor: Value Retransmission Group 0x05

Resource Resource ID Description Min Max Default Unit Module Key
TRANSMIT PAST READINGS 0x00 Transmit past readings: 0 off, 1 on. 0 1 1 1111
NUMBER OF PAST READINGS 0x01 Number of past readings transmitted in a packet. 1 15 10 1111

10. Examples

First, let's configure our sensor. We decide to set the sensor to acknowledged mode. To do this, we look at the following downlink (HEX code):

9.1. Setting Confirmed Mode

Example downlink for activating confirmed mode.

01 21 11 01 00 00 00 00 03
Beispiel für bestätigten Modus
Figure 1: Annotated example from the PDF.

9.2. Change the measurement interval to 24 times per day

Example downlink for a 60-minute interval.

01 11 11 00 00 00 00 00 3C
Beispiel für Änderung des Messintervalls (60 Minuten)
Figure 2: Example of changing the measurement interval.