Total Number of Units over 100

Hi, i know that there is a limit to the number of units on a single network
(100). We have been working on a project (HOME) and the cbus system has kept growing. Now the total number of units on the network is 103. Is this a major problem??.
It would be very hard to try to split the network now, and would also cause a major rewite of the project.
Could any one please advise ??

 

My understanding (and please correct me wiser people out there!) is that provided you don't exceed the 2amp power limit on a single network there is no real limit to the number of units, however > 100 units could lead to potential communication issues.

I am running a network with 99 units including:

1 Bridge
9 relays
15 dimmers
34 key inputs
21 flush mount multi-sensors
3 indoor corner mount sensors
9 Outdoor sensors
1 PAC
1 Ness interface
1 General Input Unit
1 Desktop AMP
1 B&W Touchsreen
1 * CNI
1 * PCI
1 * Homegate (doesn't count)

bridged to a 2nd network with 32 units with

1 Bridge
2 power supplies
29 shutter controllers.


I am reaching a similar point where I may need to add a number Desktop AMPs and a DLT pushing me over 100 units but as things stand the system is stable and there are no issues (touch wood)

Power consumption is ~1650mA which gives me some room to move.

 

There are 2 primary factors you need to consider when having lots of units on a network:
1) Current consumption and supply. You cannot have more than 2A of supply on a network or the cable may be damaged during a short-circuit condition. Too many power supplies can also affect comms.
2) AC Impedance. If this gets too low (or high) then comms will be unreliable.

The best thing to do is to make sure you've got all the correct catalogue numbers in your Toolkit database and then select the Network node on the Toolkit treeview. If the value for Impedance drops below 400 ohms you will experience comms issues. You need the impedance, including burden, to be in the range 400 -1500 ohms.

The '100 units' figure is a ballpark figure. The real thing that matters is the combined AC Impedance of the network.

 

Thanks for the clarification Newman. Impedance on my network is 837ohms, so that's reassuring.

 

If you have a burden on your network, either software or hardware, then that's going to drop your impedance down to 456 ohms, which also should be OK, but is definitely right down the low end.

 

Newman
Thanks for the information and clarifications. I am going to site tomorrow, so i will have a check on the figures.