Dragino LHT65N

Compatibility

Compatible with EpiSensor Edge over LoRaWAN.

Register it on your LoRaWAN network server with its DevEUI and keys. Edge, on the Gateway, reads its decoded uplinks from that server.

Edge reads 11 values from it, listed under Interface.

Connect it with

• 
  Gateway ZGW-20
  From €899 ex VAT Configure Gateway

Specifications

The LHT65N measures air temperature and relative humidity with a built-in sensor, and reads a second value from an external probe plugged into its connector. Dragino rates the built-in sensor at ±0.3 °C and ±3 % RH typical, with a resolution of 0.01 °C and 0.04 % RH, over -40 to 85 °C and 0 to 96 % RH.¹

Power

Battery. One 2400 mAh CR17450 Li-MnO2 cell, not rechargeable and replaceable by removing two screws on the back. Up to 10 years depending on the reporting interval; the device works down to about 2.5 V and the cell should be changed below 2.6 V.¹

Temperature range

-40 to 85 °C (built-in sensor)¹

Temperature accuracy

±0.3 °C typical, 0.01 °C resolution¹

Humidity range

0 to 96 % RH (built-in sensor)¹

Humidity accuracy

±3 % RH typical, 0.04 % RH resolution¹

External temperature probe

-55 to 125 °C; ±0.5 °C from -10 to 85 °C, ±2 °C across the full range; 0.0625 °C resolution¹

Long-term drift

< 0.02 °C per year, < 0.25 % RH per year¹

LoRaWAN

Version 1.0.3, Class A, OTAA by default¹

Frequency plans

EU868, US915, AU915, AS923, KR920, CN470, EU433¹

Default reporting interval

20 minutes¹

Datalog

Up to 3,328 records¹

Antenna

Built-in spring antenna (the LHT65S variant has an external SMA antenna)¹

Where it is used

• Fridges, freezers and cold rooms, with the external probe inside the space and the transmitter outside where the radio signal is better.

  Cold room and cold store temperature monitoring

• Room temperature and humidity in offices, stores and plant rooms, where a battery sensor avoids new cabling.

  Indoor environmental monitoring

• Hot and cold water pipe temperatures, with the probe strapped to the pipe.

  Legionella temperature monitoring

Interface

Device class

Class A¹

Regional plans

EU868, US915, AU915, AS923, KR920, CN470, EU433

Activation

OTAA

LoRaWAN version

1.0.3

Default uplink interval

20 minutes

Ports

Decoded fields

Readings and settings, with units and ranges where Dragino publishes them. R readable, W writable only.^1, 2

All values are big-endian. The first two bytes carry the battery voltage in mV in bits 0 to 13 and a battery status in bits 14 and 15. Built-in temperature is a signed 16-bit value in hundredths of a degree; humidity is in tenths of a percent.^1, 2

The lower four bits of byte 7 set the external sensor mode, which decides what the last four bytes mean: 1 is the E3 temperature probe, 2 a TMP117 probe, 4 interrupt mode, 6 an analogue input, 8 pulse counting, 9 and 10 a probe reading with a Unix timestamp, 11 an external SHT31 temperature and humidity probe. In mode 1 with no probe connected the external temperature reads 327.67 °C.¹

Datalog timestamps come from the network server through the LoRaWAN DeviceTimeReq command, so the server must support LoRaWAN MAC 1.0.3 or later. Stored readings can also be polled by downlink 31 with a start and end Unix time.¹

Setup

1. Register it on the network server

   Add the LHT65N to the site’s LoRaWAN network server as a Class A device using OTAA, with the DevEUI, AppEUI (join EUI) and AppKey printed on the sheet in the box.¹

2. Wake it from deep sleep

   It ships in deep sleep. Hold the ACT button for more than 3 seconds: the green LED blinks five times quickly, and stays on for 5 seconds once the device has joined.¹

3. Add the decoder

   Load Dragino’s LHT65N decoder for the installed firmware on the network server; it decodes port 2 uplinks into named fields.²

4. Send a test uplink

   Press ACT for 1 to 3 seconds to send an uplink at once. The blue LED blinks if an external probe is detected and the red LED if not.¹

5. Check one value

   Compare the decoded temperature with a reference thermometer beside the sensor, and confirm the external probe reads a real value rather than 327.67, before you enable exports from Edge.

Common questions

Which LoRaWAN port does the LHT65N use?

Periodic readings arrive on port 2 as an 11-byte payload, every 20 minutes by default. Port 3 carries alarm-mode samples, port 5 the device information reply and port 8 the alarm settings reply.¹

Why does the external temperature read 327.67 °C?

That is the value 7FFF, which the device sends in external sensor mode 1 when no probe is connected. Plug in the probe, or change the external sensor mode if nothing will be connected.¹

How long does the battery last?

Dragino quotes up to 10 years from the 2400 mAh CR17450 cell, depending on how often the device sends. The device works down to about 2.5 V, and Dragino advises changing the cell once it falls below 2.6 V. Any brand of CR17450 fits.¹