Installing Cbus pink cable

Hi I am just in the middle of cabling the switches and pir?s can someone please comment on the diagram to say if they think it will be ok. Obviously I will not be running the cables as direct. I know you can not run a closed loop but can run star or a tree network any help or suggestions would be great. Thanks

 

You have three cables returning to the main panel - how to plan to terminate them here?

At a switch which has a screw connection it is fine for three cables, but in a panel, typically a surface mount RJ45 connector is used which only allows one cable. From there a patch cable is used to the output modules and then a second patch lead (two ports on each output module) back to a second surface mount RJ45. (and variations of this).

As you can see, this allows for two cables from the cabinet easily.

Mick

 

I was planning on using something like this

or something with screw down connector?s before entering the panel and only have one entering. Can you suggest a better way of joining? What do you think of the rest of the wiring plan? Is there to many branch to the left of the plan or should it be ok. Thanks again for all the help

 

In the Clipsal C-Bus training manual they recommend that cables are terminated at devices, such as switches, by joining the pairs together with a bootlace crimp.

See page 18 of the following training manual.

http://www2.clipsal.com/cis/__data/page/2857/14084_C-Bus_Basics_Training_Manual_Vol_1.pdf

If you have two cables terminating at a device this recommendation is easier than if you have three cables.

With only a small variation to your cable layout you could achieve no more than two cables per device.

 

Other than the ease of terminating is there an issue with putting more than one wire into a switch. Also What about the Terminal strip that is shown on page 10 of
here

 

If you do a search on Harmonica or 8052/4RJ you'll see some other ways of joining multiple runs.

I have two networks all with multiple runs back to the main control room (10 on one and 8 on the other) and use three Harmonica's in total and have had no problems joining them this way.

Isolating the runs does have some benefits in that you are able to test areas of the network(s) if you ever need to fault-find.

 

If you mean more than one cable then no, no problem at all.

Three is really the maximum, but you may fit four if you try.

The use of bootlace crimps really does make it easier. I use them everywhere, light fittings, on the C-bus modules and on all C-bus connections. Really makes life easy and it looks so neat.

There is validity in everything everyone has posted. When I designed the routes in my hose I took a lot of effort to only have two cables at each switch and only have three if it makes sense (PIR for outside and the extra cable in running back was not worth it).

Extra locations is also important. If you think you may want a PIR or a switch there, run the cable.

Mick

 

Thanks for all the help

 

Nothing wrong with loops

I can see nothing wrong with your proposed layout, so no need for changes, but:

I really am hard pressed to come up with where the taboo about loops in the wiring of C-Bus pink cable originated from.

It simply is not true.

The only argument to justify it is that packets can travel between units by two paths of different lengths, and there might be some sort of interference between the messages arriving at different times, but this is guaranteed by C-Bus physical layer protocol to not be a problem (how the physical layer achieves this is a bit complex for this discussion.. perhaps worth a later post..).

To test the case, I wired my house as one big loop. I have a basement, main floor and a second floor, and to test the issue as much as possible, I wired each floor as a loop, and brought both ends of each loop back to a common panel (there are sub-panels on each floor for housing relays and dimmers within each floor loop). I then connected the three loops like a big three-turn spiral (to maximise loop inductance). I have roughly 400 metres of pink cable in the house. This topology has been working without any issues for the past 4 years with approximately 40 C-Bus units (and a number of RJ sockets at bedside locations, etc.) distributed on it.

In each room of the house, I have run C-Bus pink cable horizontally in the walls at switch height, so any time I might decide to add a switch, there will always be a cable available in the vicinity. Where pink cable crossed power feeds (running vertically), I always used a piece of flexible conduit for the pink cable to ensure separation.

This is not the first installation I have wired as a loop.

The one thing I would recommend against is 'blind' loops - alternative paths between units that are not easy to get to. I can imagine that this would make diagnosing faults much more difficult. This is why I brought both ends of the loop from each floor to my common panel. This allowed me to revert to a 'star' topology if it all failed to work, and allows testing each floor separately if there is a faulty unit on any floor which prevents network communication from being reliable.

Wiring with a big loop has the advantage that the dc resistance is lower between all units, so there is a more uniform dc voltage across the network.

 

Don, by loop are you saying you have a complete ring?

No reply from Darren or Ashleigh on this?

 

By loop I mean the ends of the cable run are connected together. I suppose you could call it a ring.

 

So a loop or ring does not affect the communication on the bus?

 

No.

With respect to the communication, up to 1000 metres of cable looks like a very short piece of wire, and as such, loops or any other variation in wiring topology will make no difference.