What is the limit of the number of Controllers that can be in a Continuum System?

Issue

What is the limit of the number of Controllers that can be in a Continuum System?

Product Line

Andover Continuum

Environment

Continuum

Cause

Want to know the theoretical and practical limits to how many controllers can be on one system.

Resolution

There are certainly some logical limits to how your Netcontrollers are addressed and identified in the system but for all intents and purposes you are only restricted by the IP Address.

Netcontrollers

Logically, you can have Netcontrollers addressed from 1 - 190 - so the maximum you can have in a "logical" Network is 190 Netcontrollers. However, the number of Networks you can have in a Continuum Database is only restricted by the Database itself - effectively infinite. See the article below on logical Networks.

http://buildingskb.schneider-electric.com/view.php?AID=3063

This restriction is only for Netcontrollers defined within the Infinity side of the Continuum Database and does not apply to third-party BACnet controllers.


Field Controllers (b3 / i2)

There is a definite limit to the number of subnet (Infinet or MSTP) controllers that can be strung off of a given bCX or Netcontroller. As a general rule, each comm port can support up to a maximum of 127 subnet devices. Of course this does depend on the device being used, the amount of nodes it is enabled for, and the physical installation. The number of nodes purchased does correspond to the total number of i2 or MSTP controllers that can be on that bus.

Example: If you have a bCX1 with 32 MSTP nodes this means that a total of 32 MSTP devices can be on this MSTP network and the following architecture is valid.
bCX1 with bLink;
  • (segment1) node1 to node16.
  • (segment2) node17 to node32.


If we look at a Netcontroller or Netcontroller II, these controllers have two RS-485 comm ports that can be used to support Infinet subnet controllers, up to 127 on each port and a maximum of 254 off the one controller. Now the controller would need to have both ports enabled for 127 nodes and considerations made for the amount of traffic this number of controllers would require.

Similarly, the bCX1 (BACnet) will support up to 127 nodes. One thing to note is that this also includes repeaters if they are used to extend your network or star the MSTP.

The general rule for the number of devices on an MSTP segment is a maximum of 32 nodes, this dependent on the network complying with MSTP installation guidelines for termination, distance, cable type, and that each node is a full load RS-485 transceiver.

In the case of our BACnet controllers, they use a 1/4 load transceiver so given perfect network conditions it is possible to have 127 b3 devices on the same MSTP network segment. Even though this is possible, it is always good practice to use a b-Link repeater and a max of 32 devices per network segment - this also helps to segregate the devices for troubleshooting as well.


Total Point Limits

Other than with a Cyberstation with an I/O limited Security Key, I'm not aware of any limits to the number of points that can be created in a Continuum Database; this would be limited to the size and resources of the Continuum SQL Database.

Consult the following article that has a spreadsheet to help estimate the size of your Continuum Database. It could also help to estimate your SQL requirements.

http://buildingskb.schneider-electric.com/view.php?AID=4460