Cbus networks

Client wants to install cbus in the outer building and connect it to the Cbus switchboard in the main building.
Problem is that there is no conduit to run the wire between two buildings. They are completely separate.
I can get the wireless transceivers that support point to point rs232, 485 connection. Just not sure if its even possible.
Anyone have any ideas please?
Thanks
George

 

What is the distance and how line of sight is it?

 

How does the power get to the outer building? Is it from the main building switchboard? The c-bus cabling is rated for 240V enclosures, maybe you can run it with the power feed if it is already in its own conduit. (Though its probably not the best option)

If that's the case, you can put a network bridge in and C-Bus power supplies (or relays/dimmers with power supplies) into the outbuilding to minimise any voltage drop. If you lose your connection between the networks, they will still function independently.

Alternatively, 2x 5800WCGA C-Bus Wireless gateways can bridge two wired networks. These are RF and the specs say they have a 15-20m range, 50m in open air. Can't vouch for how reliable they would be as RF can be hit and miss sometimes depending on the topography and interference from other devices.

Its a shame that the CNI's don't support C-Bus tunneling (AFAIK). You could have had one at each end connected to an IP wifi network...

Cheers

Jason

 

Distance is about 30m with little interference. Transceiver modules I was talking about will give me about 200m
connection and extremely reliable. I've tested them with rs485 data and its plug and play solution.

 

There is power conduit but I wont be able to run another cable. Outer building has Cbus units and power supply.
I can try two wireless gateways but I had mixed experience with them before. Problem was that if I use third party cbus controllers to send Cbus command thru wireless bridge (Ness m1) it was not seen on the wired network. Other way around works. I've only used one bridge to link wired network to wireless.

 

Not possible.

This has been discussed before -wireless, fibre optic and power line. Clipsal have not created the product that we all seem to ask for at one time or another.

Your only option is to try and run cable between the two buildings.

When using wireless you NEED to have an input unit (or was it an output) - there was something funny about the way the wireless module worked and we were working with one that was connected to a HA system but could not send or receive - turned out we had to include an input unit (switch) to get it to work.

 

If the wireless gateways don't sound so appealing, then...

I will probably get mercilessly flamed for suggesting this, but... is there any redundant cabling between the buildings that could be used? Ethernet, security cable, telephone pairs (this is cat3) rg6, figure 8... Anything that could suffice as a cbus surrogate cable or be used as a pull through for c-bus cable? The protocol is not gigabit ethernet ,speed wise ,and is effectively just two wire. I read a post from Ashley that said you could split out two pairs from an Ethernet cable and share with the c-bus wiring.

Here's the link:
https://www.cbusforums.com/threads/best-practice-for-c_bus-over-ethernet.10127/#post-54459

Cheers

Jason

 

Hi Jason,
Thanks for the suggestion. I have done it before. Unfortunately not much you can pull thru 20mm conduit. I have one wireless bridge and will try to get another one and see it it works properly.
Cheers
George

 

You just need an input unit to link 2 x wireless gateways together under the same house code, then the input unit can be removed and the gateways will work as a link, just be aware that you technically end up with 3 C-Bus networks as the wireless is its own 'Network'just without any units, to make it work transparently you need to ensure you push your applications across properly.

 

Hope it works out for you. Be nice if you could let us know the outcome.

Failing the wireless option working, it may require using one of the cables as a sacrificial one to pull a new one with a CBus cable through the conduit.

Patience and lots of silicon spray for a conduit lubricant...

Cheers.

Jason

 

Here’s my 10 cents,
a few ideas,
Are there any cat5/6 cables going between buildings for Ethernet? If so use one of them for cbus coms and install a wifi point to point link for the Ethernet

I’m not sure if this would work I guess in therory it would, get 2x cbus pc interface (the rs232 ones) and join them with a crossover cable, it would be easy to put on the bench and test proof of concept

this would defiantly work but would be a bit spendy $wise, 2x shac controller(one on each side) and make them talk to each other over rs232 or Ethernet with a bit of lua script.


I think the cbus wireless gear is not available anymore... but you might be able to find some on eBay?

 

It won't work. Not unless you stick some processing power in between to convert the received format into the correct Tx format, which is not trivial.

 

Thanks everyone for the suggestions.
Cheers
George

 

1) 2 wiser Shacs, one on each CBus network, both connected to the same Ethernet network
2) 2 homebridge one for each CBus network( connecting using a cni or pci) and connect the switch to the output using HomeKit
3) homegate connected to a cni on each CBus network.

 

Does anyone maybe have wireless gateway laying around for me to borrow or buy?
I have one and need a second one to see if it works properly with HA and within wireless range for the intended purpose. Thanks
George

 

If you are still looking for one, ebay has a listing yesterday for a used wireless gateway here:

https://www.ebay.com.au/itm/Clipsal...m3b4d701bb7:g:mi0AAOSwWNBfSK2T&frcectupt=true

Cheers

Jason

 

Thanks Jason

 

Just wondering if I can utilize only one pair of cat5 cable for the Cbus. Is it enough for the current to flow thru on short distances or I still need two pairs.
I want to try the following configuration.
One pair for rs485, two for internet and one for Cbus.
Cheers

 

I guess it comes down to how much current is on the network. If two c-bus Cat5 conductors in the network can support a stated maximum of 2000mA (as per c-bus cable specs) and it’s a linear relationship, then 1 conductor should probably support a maximum of 1000mA on a given network. If that criteria was met and was clearly documented on the install that total CBus current should not exceed 1000mA then maybe you would get away with it. The danger is if someone else comes along and sticks another power supply or two when adding to the network and pushes the current closer to 2000mA over the one conductor network segment.

The other consideration is cross talk between the adjacent pairs carrying the rs485 (-7 to +12V and Ethernet +/- 2.5V or ~ + 48V if it’s PoE) and c-bus (+ 36V). Someone like Ashley would probably know if this is something to worry about. How long is the cable run and what is the amount of c-bus current supplied to the network in question?

Now with the above 2000mA maximum c-bus network current in mind... Cat5e cable is 24AWG cable which is 0.2mm squared in cross sectional area. This cable has a maximum current rating of 2A. However, maximum current is defined as the current where the conductor or insulation melts!

So c-bus has a factor of safety of 2:1 wrt conductor current.

So if you are thinking of going over 1000mA for your network on one conductor, your factor of safety is getting closer to 1:1 which is not desirable...

If you average 20mA (usually 18mA) per CBus device on your network, at 1000mA then you could still have a maximum of 50 CBus units. If you only used one conductor at one “end” of the network with one device or a bridge at the other end you would probably be ok.

What will be on either side of the proposed one conductor network segment?

Cheers

Jason

 

I have about 1200ma available on the network but as far as the units consumption it will only require 200ma on the other segment of the network so you have 5:1 safety ratio on one 24awg conductor.
Theoretically if unit require 2amp of current it will be the limit of the conductor, but if unit requires only few milliamps single conductor should be enough?
Thanks
George