Chapter 8

Finding your sensors

Before adding the Bluetooth sensors you need to know the slot number of each one. It takes two minutes and saves a lot of searching — because the numbers are not handed out the way you would expect.

6 minutes Last verified: 22.09.2026 DE EN

What a slot number is

Every paired Bluetooth sensor gets a slot from your CampMatic. That number appears in all the topics the sensor publishes on. Without it you will not find its values.

The numbers run across all sensor types

This is where most people get it wrong. Slots are not counted per sensor type but consecutively across all of them. Your gas bottle may sit on slot 1, the battery monitor on slot 2 and the Ruuvi on slot 3 — and on another device the spread looks completely different.

There is no rule you could apply. You have to look them up.

Reading your own numbers

The easiest way is inside Home Assistant itself — no extra software, no command line.

Start listening

Open Settings → Devices & Services → MQTT and click Configure next to Mosquitto broker. Under Listen to a topic enter:

Listen to a topic text

campmatic/<GERAETE_ID>/+/config

Click Start listening. Within a few seconds one line per sensor type appears.

Reading the replies

What comes back looks roughly like this — a device with four paired sensors:

Example reply json

campmatic/<GERAETE_ID>/mopeka/config
  [{"slot":1,"type":"mopeka_pro","mac":"CD:B3:…","name":"Main bottle","tank_type":"EUROPE_6KG"}]

campmatic/<GERAETE_ID>/bm2/config
  [{"slot":2,"mac":"3C:AB:…","name":"House battery"}]

campmatic/<GERAETE_ID>/ruuvi/config
  [{"slot":3,"mac":"F3:89:…","name":"Ruuvi"}]

campmatic/<GERAETE_ID>/truma/config
  [{"slot":4,"mac":"7C:72:…","name":"Truma Level Control 1"}]

The value behind slot is the slot number. Note it down for every sensor you own. The name next to it is the one you gave in the CampMatic app — that is how you tell which sensor is which.

Several sensors of the same kind

With two gas bottles or two battery monitors you get several entries in the same line, each with its own slot number:

Two gas bottles json

campmatic/<GERAETE_ID>/mopeka/config
  [{"slot":1,"name":"Bottle left","tank_type":"EUROPE_11KG"},
   {"slot":5,"name":"Bottle right","tank_type":"EUROPE_11KG"}]

In that case you simply create the sensors from the following chapters twice — once per slot number, with different names.

Nothing there?

If the display stays empty, no Bluetooth sensor is paired with your CampMatic. Pairing happens in the CampMatic app, not in Home Assistant. If you do not own any of these sensors, skip the next chapters and go straight to the dashboard.

How the topics are built

All Bluetooth sensors follow the same pattern. Once you have seen it, you can assemble any topic yourself:

Topic structure text

campmatic/<GERAETE_ID>/<kind>/<thing>_<SLOT>/<reading>

  <kind>      mopeka | bm2 | ruuvi | truma
  <thing>     bottle | monitor | tag | bottle
  <SLOT>      the number from above
  <reading>   e.g. voltage, temp_c, raw_tof

Examples:
  campmatic/<GERAETE_ID>/mopeka/bottle_1/raw_tof
  campmatic/<GERAETE_ID>/bm2/monitor_2/voltage
  campmatic/<GERAETE_ID>/ruuvi/tag_3/temp_c
  campmatic/<GERAETE_ID>/truma/bottle_4/gas_percent

Each type has its own word

Note that the middle word differs per sensor type: the gas bottle is bottle, the battery monitor monitor, the Ruuvi tag. There is no guessing this — use the examples from the following chapters.

Before you move on

You have noted the slot number of every sensor you own
You know which name in the app belongs to which number