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Temperature and humidity sensor

comtac LPN CM-4 LoRaWAN decoder and payload format

The comtac LPN CM-4 is a LoRaWAN temperature and humidity sensor that reports humidity and temperature. It is rated IP65, it runs on a replaceable LiMn02 1.5Ah AA battery and it works from -20 to 80 °C.

comtac LPN CM-4
Official decoderProduct page

Payload format

An uplink from the device as it arrives at the network server, and what the official decoder returns for it. Examples come from the decoder's own test cases.

Example 1 · fPort 3

Payload (hex)

01 12 02 97 04 0A A3 1D 0A 8D 1E 0A 98 1E 0A A0 1E 0A A9 1E 0A A0 1E 0A 9C 1E 0A 9D 1E

Decoded (JSON)

{
  "batLevel": 75.5,
  "humNOW": [
    29,
    30,
    30,
    30,
    30,
    30,
    30,
    30
  ],
  "tempNOW": [
    27.23,
    27.01,
    27.12,
    27.2,
    27.29,
    27.2,
    27.16,
    27.17
  ]
}
FieldValue
batLevel75.5
humNOW[29,30,30,30,30,30,30,30]
tempNOW[27.23,27.01,27.12,27.2,27.29,27.2,27.16,27.17]

Example 2 · fPort 3

Payload (hex)

01 12 09 97 03 0A 8D 23

Decoded (JSON)

{
  "batLevel": 75.5,
  "humNOW": [
    35
  ],
  "tempNOW": [
    27.01
  ]
}
FieldValue
batLevel75.5
humNOW[35]
tempNOW[27.01]

Specifications

Manufacturer
comtac
Model
LPN CM-4
Type
Temperature and humidity sensor
Measures
humidity, temperature
Protection
IP65
Battery
LiMn02 1.5Ah AA battery (replaceable)
Operating temperature
-20 … 80 °C
LoRaWAN regions
EU863-870

Connect it to Cloud Studio IoT

  1. 1

    Register the device in your network server

    Add it to The Things Stack, ChirpStack, Actility ThingPark or LORIOT with its DevEUI, JoinEUI and AppKey and the frequency plan of your region.

  2. 2

    Apply the decoder

    In The Things Stack, pick the model from the device repository and its decoder is applied for you. In ChirpStack v4, paste the official decoder as the device profile's JavaScript codec.

  3. 3

    Connect the network server to Cloud Studio IoT

    Set up the integration once per network server; every device registered there then reaches Cloud Studio IoT with its decoded values.

  4. 4

    Build dashboards and alarms

    The decoded fields become device variables for dashboards, alarms by email or SMS, and scheduled reports.

See your comtac LPN CM-4 on a dashboard

Start a free trial, add the device with its DevEUI and get dashboards and alarms from its next uplink.

Talk to us

Frequently asked questions

Device facts and decoder examples: The Things Network Device Repository (Apache-2.0) · commit 7693223, imported 2026-10-05.