Unipi Extension xG18 - a brand-new 1-Wire/RS-485 extension module for your project

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26/3/20 Discover new temperature measurement possibilities with the Unipi Extension xG18 module for up to eight Unipi 1-Wire temperature sensors. 

1-Wire temperature sensors are a cheap and simple method of measuring temperature, that is suitable for a wide range of automation tasks. However, especially large-scale projects can soon run into technical limitations of the 1-Wire bus - namely the limit of 15 devices per bus, and the bus length of max. 200 m. So, what to do if your project's requirements exceed these limitations?

For such cases, we now introduce a solution in the form of the Unipi Extension xG18 1-Wire/Modbus RTU extension module.

Unipi Extension xG18

- number of 1-Wire channels: 8
- type of 1-Wire connector: RJ45
- sensors per channel: 1
- power supply: 5-24V DC
- size: 72 × 91 × 22 mm
- weight: 110 g
- installation: 35mm DIN rail
- chassis: aluminium (IP20 protection)
Display on the Unipi e-shop

What are the main advantages of xG18?

  • An affordable method of temperature measurement
  • Easy connection of up to 8 1-Wire temperature sensors (RJ45 connector)
  • 1-Wire channels are separated to improve the reliability of measuring
  • Applicable in any system featuring RS-485 and Modbus RTU support
  • Allows for the reduction of cabling, improves the reliability of the controlled system
  • Suitable for extensive installations
  • Possibility to connect up to 32 modules to a single RS-485 line

A practical solution for temperature measurements

Unipi Extension xG18 is a simple and reliable tool for connection and reading the temperature of up to eight Unipi 1-Wire temperature RJ45 - you can use any of the offered cable lengths. For communication with the control system, the module uses the RS-485 serial interface and the Modbus RTU protocol. Although designed primarily for the use with Unipi controllers, you can connect xG18 to any system or device featuring an RS-485 interface and Modbus RTU support. 

To improve measuring reliability, the module's 1-Wire channels are separated from each other and support only a parasite connection of a single DS18B20 per channel. Compared to the standard 1-Wire connection, this arrangement prevents failure of the entire bus caused by a single faulty sensor. Up to 32 modules can be connected to a single serial bus, allowing you to create extensive networks with up to 256 sensors. 

The mentioned features make the xG18 suitable especially for: 

  1. boiler rooms, heat exchanger stations, refrigeration facilities and other installations requiring a large number of temperature sensors
  2. industrial facilities with large distances between individual measuring points
  3. installations with high requirements on measurement reliability. 

Example of xG18's usage

Software support

The xG18 can be used with any device featuring the RS-485 interface and software supporting Modbus RTU communication.

Direct software support of the xG18 module for all Unipi controllers will be a part of the upcoming 2.3.0 release of the Mervis IDE development environment. The release is currently in closing stages of its development - we will inform you on our website and in our newsletter once the release will be published.

Further info

The xG18 module is powered by 5 - 24V DC voltage. The module is designed for installation onto a standard DIN rail (holder and mounting screws included in the package). Module's components are protected by a durable aluminium chassis with IP20 protection. A set of LED indicators serve for the indication of 1-Wire channel status, RS-485 communication and power. 

Further information

Unipi Extension xG18 is already available on the Unipi e-shop - here, you can also find additional info about the device. Technical documentation and other useful info are available on the Unipi Knowledge Base.


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