The Unipi Extension xG18 extension module is a simple and reliable tool for connecting and reading temperature data from up to eight Unipi 1-Wire temperature sensors (RJ45 connector).
The Unipi Extension xG18 extension module is a simple and reliable tool for connecting and reading temperature data from up to eight Unipi 1-Wire temperature sensors- you can use any of the offered cable lengths. For communication with the control system, the module uses the RS485 serial interface and the Modbus RTU protocol. Although designed primarily for use with Unipi controllers, you can connect xG18 to any system or device featuring an RS485 interface and Modbus RTU support.
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 RS485 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 RS485 line
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:
- boiler rooms, heat exchanger stations, refrigeration facilities, and other installations requiring a large number of temperature sensors
- industrial facilities with large distances between individual measuring points
- installations with high requirements on measurement reliability
Example of xG18's usage
For a practical example of using Extension xG18's application that includes a connection to Unipi Gate gateway and sending the data to a cloud platform, please visit the Sending temperatures from Unipi Gate to a ThingsBoard cloud case study.
Communication parameters of the serial bus can be configured either on the hardware side via DIP switches, or on the software side through Modbus registers. Hardware configuration is sufficient for most applications, while the software configuration offers broader options, namely a broader range of addresses and bitrates.
Unipi xG18's DIP switches
The xG18 module is powered by 5–24V⎓ 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 aluminum chassis with IP20 protection. A set of LED indicators serve as the indication of 1-Wire channel status, RS-485 communication, and power.
The xG18 can be used with any device featuring the RS485 interface and software supporting Modbus RTU communication.
From the 2.3.0 release of the Mervis IDE development environment, the module has full software support. A tutorial for connecting the xG18 to Mervis IDE is available on this link.
Technical documentation and other useful info are available on the Unipi Knowledge Base.
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