1-wire extension setup

A guide to installing and configuring the 1-Wire Extension

Get more information about the 1 Wire

Technical Data

  • Connected with Loxone Link
  • 1x 1-wire Interface (5V output max 50mA)
  • 16.3 kbit/s
  • Supports 20 sensors
  • Unlimited number of iButtons
  • Dimensions: 35.5 x 88 x 57 mm (2 TE)
  • Power consumption approximately 30mA
  • Configure with Loxone Config
  • Power supply: 24VDC
  • Protection: IP20
  • Ambient temperature: 0 to 50°C
Technical Data


  • Mount the 1-Wire Extension on the DIN rail.
  • Connect 24VDC power supply, but do not switch on until the whole installation is completed
    (We recommend you loop power through the Miniserver)
  • Connect the Loxone Link.
  • Connect the 1-Wire connector to the 1-Wire bus
  • Note: If it is the last extension, terminate the Loxone Link with a 120Ω resistor
    (Included with the Miniserver)
  • Turn on the power supply
  • After a few seconds, the left LED will flash green if the 1-Wire Extension is already configured, or orange if not


1 Wire extension dimensions

Supported 1-Wire Components

1-Wire Device Family Code Description

Default polling cycle [s]

Econo 1-Wire Digital Thermometer


Temperature Sensor
Range: -55°C to +85°C
Accuracy: ± 2°C from -10°C to +85°C
Resolution: 12 Bit or 0.0625°C


Programmable Resolution 1-Wire Digital Thermometer


Temperature Sensor
Range: -55°C to +85°C
Accuracy: ± 0.5°C from -10°C to +85°C
Resolution: 12 Bit or 0.0625°C

Parasite Power Digital Thermometer
10 Temperature Sensor
Range: -55°C to +125°C
Accuracy: ± 0.5°C from -10°C to +85°C
Resolution: 9 Bit or 0.5°C

Serial Number iButton (SHA)
18 Access Control
Serial Number
01 Access Control
Smart Battery Monitor
26 AD-Converter and Temperature Sensor

Temperature Range: -55°C to +125°C
Resolution: 13 Bit or 0.03125°C


Voltage VDD

Voltage Supply
Range: 0V - 10.23V
Resolution: 10mV


Voltage VAD

Voltage at the input pin of the AD Converter
Range: 0V - 10.23V
Resolution: 10mV


Voltage Vsens

Voltage at an external resistor (Rsens) for indirect current measurement
Range: -0.25V - 0.25V
Resolution: 0.2441mV
Calculation of current: I = Vsens/Rsens


This chip is used by many manufacturers as a humidity sensor. To do this, the output voltage of an analogue humidity sensor is set to the AD-Converter input pin (VAD) of the DS2438. To convert the voltage into a humidity measurement, consult the manufacturer's formula.

Example - WireGate Multisensor "MS-THS13-BRK":

    In order to convert voltage [V] into humidity [%], use the 'Formula' object in the 'Mathematics' category in PLC.  

Please note that a short polling cycle with many temperature sensors will slow the bus communication down, so therefore the polling cycle should preferably stay at the default of 60 seconds. 


A characteristic of one wire sensors is how simple they are to use. However, please do pay attention to the following wiring instructions to ensure you get the optimum signal transfer for your sensor.

  • When installing the sensor, use a cable with a cross section of at least 0.6mm (e.g. Cat5e).
  • We recommend a maximum of 20 sensors on one 1-Wire extension regardless of wiring topology
  • The following wiring instructions should be treated as a guide only. Depending on the environmental factors, including cable length and number of sensors these instructions can vary.


We recommend you use data cable (Cat5e, Cat6 or Cat7), and you need to use one twisted pair for GND and data.
For longer distances or when running alongside mains cables use STP (shielded twisted pair) cable.  DQ and GND should be connected using a twisted pair so the data signal is twisted against GND.

Optimal wiring topologies

Bus topology

Bus topology

Bus topology without branches is best suited for wiring. It allows a maximum range of 350m with a total of 20 sensors.

Bus topology with stubs

Bus topology with stubs

This topology can produce similar results to the bus topology without branches. The maximum cable length is slightly reduced to 300m when connecting 20 sensors.

Further wiring topologies

Bus topology with long stubs

Bus topology with long stubs

One wire installation in bus topology with long stubs is not recommended as it reduces the maximum total cable length to 100m with 20 sensors.

Star topology

Star topology

Star topology is recommended only for small installations, since all the sensors are brought together at one point. The maximum total cable length is 100m for 20 sensors.

Ring Topology
Ring topology is not supported in one wire installations. If the sensors are connected in a ring, then no signals are received.

Wiring a 1-Wire Sensor

This is a schematic diagram for connecting the one wire temperature sensor DS18B20+. The pin assignments can vary between sensors so please refer to the manufacturer's datasheet.

Wiring the 1 Wire Extension

Parasitically powered: When wiring so the 1-Wire sensor is parasitic, GND and VDD are connected together and GND is connected to the extension. Ground and data should be twisted against each other.

Extension DS18B20+ 1-Wire Temperature Probe 1-Wire Temperature Probe (ordered before 2015)
(A) DQ (2) DQ (White) DQ (Red) DQ
(B) GND (1/3) GND/VDD (Brown/Green) GND/VDD (White/Green) GND/VDD

Note that not all one wire sensors can be used with parasitic power supply wiring topology. Please refer to the manufacturer's datasheet.

Separately powered: All three pins of the sensor should be connected to the Loxone 1-Wire extension. Ground and data should be twisted against each other.

Extension DS18B20+ 1-Wire Temperature Probe 1-Wire Temperature Probe (ordered before 2015)
(A) DQ (2) DQ (White) DQ (Red) DQ
(B) GND (1) GND (Brown) GND (White) GND
(C) VDD (3) VDD (Green) VDD (Green) VDD

1-Wire temperature sensors can be hidden behind switch plates due to their small size. It is important that the space behind is sealed though to prevent drafts and poor readings. Because you use a CAT cable to wire the 1-Wire sensors and switches the remaining cores can be used for the switch plate.

Wiring an iButton reader

The iButton reader is connected to the Loxone 1-Wire Extension. The white wire is wired to 'DQ' on the extension and the grey wire is wired to 'GND'.

The yellow wire is the common ground for both LEDs. Green = Green LED, Red = Red LED. Both LEDs can be directly driven of 24V, we recommend to use digital outputs for this. 

Wiring the iButton

If you have purchased your iButton Reader before 2015, then no current limiting resistors are built into the product and the LEDs must be driven as follows.
Green LED: Operating voltage 2.1V, current 20mA
Red LED: Operating voltage 1.95V, current 20mA

Since the iButton is the active component in the system, you can attach only one iButton reader for each 1-Wire Extension, if you want to tell which reader the signal was coming from. If you do not mind which reader the iButton has been identified at then you can attach as many readers as you wish to the 1-Wire extension. Maximum number of iButtons per reader is unlimited.

Configuring Extensions


To add one or more extensions to the program the simplest way is to connect up the extensions to the Miniserver using the Loxone Link and looping power. Then do a search in Loxone Config by pressing the button "Peripheral Search", which will bring all the connected extensions. You can highlight a single extension, give it a name and then click Create device which will add in the highlighted extension. Or you can click on Create all devices which will add all the connected extensions in to the program with the correct serial numbers. 


If you have installed several extensions of the same type and cannot identify which one is which (for example 2 DMX extensions) then you can use the software to identify a device. Simply click on the device in the periphery tree and the extension will flash red, green and yellow very quickly so you can identify it.


If there is no physical extensions connected to the Miniserver they cannot be found in the search. However you can add the extensions to the program so you can configure a system before installing. In the configuration software, connect to your Miniserver and download the existing configuration (if there is one) from the Miniserver.

Select the 'Devices' drop-down menu on the Periphery tab and select the required extension, then fill in the serial number in the properties.

Extension Replacement

If an extension has been replaced you need to add the serial number in the properties. Click on the extension in the periphery tree. Enter the serial number of the extension in the properties section. 

Serial number
The serial number is on the back of your extension. You can find the number just below the barcode (see picture).

An Extension can also be replaced in the Peripheral Search.

Mount the new Extension and run the Peripheral Search. Highlight the Extension (not used) and choose the device you would like to replace in the drop-down menu.

Finally press "OK" and save your program into the Miniserver. The Extension has now been replaced.

Add in 1-Wire devices

Select the 1-Wire Extension in the Periphery tree window, then click on '1-Wire Search' in the Context tab on the top toolbar:

Select the sensor in the Search results and give it a name, then click on 'Create device'. At this point you can also assign the iButton to a particular user, by selecting it from the drop down list and clicking 'Assign to user'. Now this iButton serial number will be displayed in the user properties.

The sensor is displayed in the Periphery tree, and can now be used in the pages:

Identifying 1-Wire Sensors

The easiest approach is to connect each sensor one after the other to avoid confusion. You can also connect all the sensors and then change the temperature of each sensor individually to identify it using Liveview.

Find out more

Contact us


Icon config
1-Wire Quick Connection Guide (pdf)



Find out more on Wikipedia


1-Wire EG Declaration of Conformity (pdf)


RoHS Declaration of Conformity (pdf)