Sentry Lorawan

SENTRY LoRaWAN telemetry module

SENTRY is a dedicated portfolio of Industry 4.0 enabled compact pressure and temperature sensors powered using batteries. Units are designed for harsh industrial environments where dust or humidity pose a risk to traditional telemetry installations.

Example use: Telemetry unit for measuring gas pressure and temperature in pipes.

Every unit contains a sensor part and telemetry part. Telemetry unit contains a rechargeable battery and telemetry radio, which reads sensor information in configured periods and uses radio uplink to send measured information to a SCADA or other industrial backend.

Telemetry part is treated as interchangeable unit, hence while one telemetry unit is being recharged any other telemetry unit can be used in its place and the same configuration will be used for uplink configuration. Configuration of the complete solution is stored in the sensor part. See below for selection of sensor compatible with SENTRY platform.

Configuration of the device is done using Bluetooth LE interface – see section “Configuration” for more details.

Depending on the configuration, the battery lasts for about 20.000 measurements sent to the uplink system (See section “Battery life-cycle”. The whole telemetry part, including the empty battery, is replaceable without the need to touch the sensor part and without use of any tools.

Sensor module options

Technical details

Dimensions of telemetry module: 182 mm length x 27mm dia.
Telemetry housing material: Polyacetal (POM)
Standard operation conditions: -20 to 60 degrees Celsius
IP rating: IP66
Telemetry radio: 868 MHz LoRaWAN
Configuration interface: 2.4 GHz Bluetooth 5.1 / LE

Pin configuration of sensor probe:
1 VCC IN
2 GND
3 UART RX (sensor uC)
4 UART TX (sensor uC)
5 reserved / not connected
6 CONNECTED TO 7
7 CONNECTED TO 6

Pin configuration of telemetry module:
1 VCC OUT FOR SENSOR
2 GND
3 UART TX (telemetry uC)
4 UART RX (telemetry uC)
5 reserved / not connected
6 CHARGER / BATTERY +
7 VCC TELEMETRY MODULE

Telemetry radio information

Technology: LoRaWAN (LoRaWAN spec 1.0.2 certified radio)
Frequency range: 868 MHz
LoRaWAN activation: OTAA (Over-the-Air Activation) only

DevEUI, AppEUI and AppKey are randomly generated - can be changed using configuration interface or during ordering.

Antenna for the telemetry unit is embedded inside the plastic enclosure of the telemetry unit and currently it is not possible replace this internal antenna with an external antenna. We only use high-efficient PIFA antennas in our products.

Battery life-cycle

Battery chemistry: 3.2V LiFePO4

Charger: DTX-CH-1LiFePO4 Mk1

Depending on the configuration of the device and the frequency of transmitting the data in average the devices battery life-cycle is about 20.000 measurements with uplink transmissions before the battery has to be recharged.

This means that if the device is gathering data and transmitting every 30 minutes the battery life is around 14 months.

SENTRY is monitoring its battery level where this information can be used to schedule maintenance battery replacement.

Max number of recharges is set to 1000 cycles.

Charging ambient temperature: 0 – 45 degrees C

Configuration

Configuration of the unit is done using dedicated Android application ‘N5 Console’ using Bluetooth LE mobile phone or tablet interface (available on all modern devices on the market).

The latest version of the application is available on http://www.moirelabs.com/dl/

More complex tasks and logic of the device are done on firmware level by turnkey firmware development for specific customers project. This is a flexible process giving customers the ability to specify details on how the device should behave under specific conditions.

Compliance

Compliant with RED - EU directive 2014/53/EU

Payload decoder / Packet parser

The device transmits several types of packets which are distinguished by the first byte in the packet:

  • 0x42 (HEX) = battery status packet
  • 0x43 (HEX) = start packet - device has just been started / rebooted
  • 0x61 (HEX) = standard telemetry packet
  • 0x62 (HEX) = link test packet

0x42 - battery status packet

# packet is a python3 bytearray
out["battery_adc"] = int(packet[1])

0x61 - standard telemetry packet

# pl is a python3 bytearray
out["Primary value (float)"] = round(struct.unpack("<f", pl[0:4])[0], 3)
out["Secondary value (float)"] = round(struct.unpack("<f", pl[4:8])[0], 3)
Primary value for pressure sensor is pressure.
Primary value for temperature sensors is temperature.

Secondary value for pressure sensor is temperature.
Secondary value for temperature sensor must be ignored.

(c) Moire Labs