# 1-Wire BBO and ICU pinouts
Inside DBU020 there are black and grey RJ12 sockets.
They use different 1-Wire pinouts called BBO and ICU shown in the table below.
The RJ12 socket pins numbering looks as below. It is a view into the female socket, where the plug is connected.
The pins with no signal name are not connected.
| Pinout | 1 | 2 | 3 | 4 | 5 | 6 |
| ----------- | - | -- | ------ | --- | --- | -- |
| BBO (black) | | | 1 Wire | GND | | 5V |
| ICU (grey) | | 5V | 1 Wire | | GND | |
The black connectors inside DBU020 are 1-Wire master sockets and they use BBO pinout.
All the ICU digital sensors are equipped with a cable with RJ12 plug which uses ICU pinout.
DBU020 has a built-in BBO to ICU pinout converter to enable connecting digital temperature sensors directly to DB020.
The middle black BBO socket is connected using a / to the grey socket marked BBO, which is a converter input. The four grey sockets marked ICU are the converter outputs that can be used to connect ICU digital sensors. Two free BBO sockets can be used to connect RD022 splitters if more ICU sockets are needed. The RD022 splitter also converts BBO to ICU pinout as described in chapter [RD022 splitter](/bbo-gateway-installation-manual/bbo-gateways/xbb006-bbo-1-wire-gateway/rd022-splitter.md).
Both BBO and ICU sockets can be used to connect [FH009/FH010 environmental sensors](/bbo-gateway-installation-manual/bbo-gateways/xbb006-bbo-1-wire-gateway/fh009-fh010-environmental-sensors.md) or [XBT006 1-Wire Interface for 4-Wire RTD PT100](/bbo-gateway-installation-manual/bbo-gateways/xbb006-bbo-1-wire-gateway/xbt006-1-wire-interface-for-4-wire-rtd-pt100.md) which have different types of 1-Wire connectors with screw terminals, providing the 1-Wire lines will be connected accordingly as described in their relevant chapters.
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