19" Rack Mount Migration

19 inch rack cabinet
This project is more of a migration than something new. For the last few years, all of our home automation equipment has sat in our loft, on home-made wooden shelves. Firstly, we need a bit more space and secondly, it really is time that the whole installation was tidied up!

The cabinet we are using is a 'half-height' cabinet that is about 860mm high × 522mm wide × 452mm deep. Most of it will be open shelves but we do plan to put a front and rear cover on with suitable cooling. Because our 1-Wire network and USB output boards are already within the rack, we will be using them to monitor the temperature of various components in the rack and switch on 12V cooling fans as required. We also plan to have a high-flow mains-powered fan at the top of the cabinet.

Some people call this their 'node 0' but, that sounds a bit geeky to us :-)

Shelves

19 inch rack cabinet
19"(482.6mm) rack shelves come in heights marked as 1U, 2U, 3U, etc. 1U equates to 44.4mm, 2U to 88.9mm and 3U to 133.4mm.

Most of the shelves we are using are 3U to enable easy access to equipment. We bought vented ones so that we can use the many holes for fixing things to the shelves.

Layout & Wiring

The list below leaves some space for expansion. The order of the shelves / components in the rack, from top to bottom are:

Cooling / Extraction

6 - Mains powered high-flow extraction fan, controlled by our Home Control System (HCS).

HCS Mini-ITX

5 - This shelf holds the main home automation processor, running our Home Control System (HCS). There is also an 8-port USB hub on this shelf for the GSM SMS Modem, etc.

HCS Network Switch

4 - This shelf contains a 16-port Gigabit Ethernet switch and suitable voltage regulator. The switch is for all of the core home control and security elements and doesn't inlcude entertainments and general computing in the house. These are routed via another switch.

2U 12V UPS

3 - Our 12V UPS powers all the core home control computing and network elements.

1-Wire Input

2 - This holds the core elements of our 1-Wire network and our 1-Wire input board.

USB Input

1 - To keep the wiring of all the sensors simpler and tidier, the bottom shelf contains our USB I/O boards. This means the wires from the sensors come in at the bottom and don't have to run up any higher.

Summary

You don't need a 19" rack cabinet to do home automation! Most of the equipment these days is very compact and would fit into a much smaller enclosure. We have taken this approach because it more easily supports us trying out technologies and testing things. Most of the space in our cabinet is empty and we could quite easily move to 19" rack half the height of the one we are using.

We do like the having electronics that are left running 24 x 7 housed in a metal enclosure though. It would prevent a potential fire spreading and we have also fitted a networked smoke alarm into the top of the cabinet.

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