External Temperature Sensors (1-Wire / DS18B20)

GLIDER supports up to 8 DS18B20 digital thermometers connected over the 1-Wire bus. The sensors connect to one of the two 1-Wire ports on the GLIDER terminal block (W1 or W2).

This page explains how to wire the probes, scan them in, and read out temperatures.

tip

For the alarm configuration tied to these sensors, see Configuration → Alarms.

Hardware

GLIDER exposes the 1-Wire bus through two physical ports, both electrically equivalent and sharing the same internal Maxim DS2484 1-Wire master:

Port	Power	Data	Ground
W1	W1V	W1D	W1G
W2	W2V	W2D	W2G

Standard HARDWARIO DS18B20 cable assemblies have three wires:

Wire color	Function	Connect to
🔴 Red	VCC (power)	W1V or W2V
🟡 Yellow	Data	W1D or W2D
⚫ Black	GND	W1G or W2G

tip

Both ports share the same logical 1-Wire bus inside GLIDER. The 8 logical "slots" the firmware tracks are independent of which physical port the probe is plugged into - bind by ROM code, not by port.

Step 1 - Wire the probes

1. Power the GLIDER off before wiring.
2. Strip the three wires of each DS18B20 cable and connect them to either W1 or W2 as shown above.
3. Power the device back on.

You may mix probes across W1 and W2 freely - both ports drive the same bus. The 8 slots are software-defined and bind to the ROM serial number of each DS18B20.

Step 2 - Scan the bus

Once the device is powered, ask the firmware to discover the connected sensors.

Via RTT console

therm scan

Via AT console

AT$SHELL="therm scan"

Example output:

Found 1 sensor(s):
 [1] 28ff12b05316031d <- NEW
 Slot 2: (empty)
 Slot 3: (empty)
 Slot 4: (empty)
 Slot 5: (empty)
 Slot 6: (empty)
 Slot 7: (empty)
 Slot 8: (empty)

Save changes? [y/N]

The <- NEW annotation marks a ROM code that the firmware has not seen before. Press y + Enter to bind the new sensor(s) to the proposed slots and reboot.

To skip the confirmation step (useful for scripts or factory provisioning):

therm scan --save

This binds and reboots in one shot.

To also delete slots whose ROM codes are no longer on the bus:

therm scan --clear-missing

Step 3 - Read a temperature

Once a sensor is bound to a slot, read its temperature with:

therm read 1

(replace 1 with the slot number 1-8). To read every populated slot at once:

therm readall

Example output:

Slot 1: 23.50 °C
Slot 2: 24.62 °C

The temperature is reported in °C with 0.01 °C resolution. Unsuccessful reads (probe disconnected, CRC error, …) return NaN and are sent as null in the cloud payload.

Step 4 - Inspect slot state

therm state

Shows the current slot bindings, the most recently measured temperature, and read/error counters.

Manually binding a sensor to a slot

If you know the ROM code of the probe (for example from a label), you can bind it directly without scanning:

therm config 1 28ff12b05316031d

…and then save:

AT&W

How temperatures appear in the cloud

Each populated slot is included in the thermometers array of the CBOR payload:

thermometers:
 - slot: 1
 temperature: 23.50
 - slot: 2
 temperature: 24.62

Empty slots are omitted from the payload (they do not appear as null). A failed read is sent as temperature: null.

For the full schema, see CBOR Payload.

Combining with alarms

Each thermometer slot can be tied to one or more alarm rules that trigger when the temperature crosses a configurable threshold:

alarm config 1-enabled true
alarm config 1-therm 1 # watch slot 1
alarm config 1-threshold 30 # trigger at 30 °C
alarm config 1-hysteresis 5 # release at 30 − 5 = 25 °C
AT&W

For the full alarm reference see Configuration and the Shell Commands page.