Control Network Newsletter
Remote Access Configuration for Multiple Buildings
To enable remote access to a BACnet system across a multi-building network, the building automation system (BAS) must be integrated with a secure and scalable networking infrastructure. A new application note explains how to configure Contemporary Controls' BASrouters (BASRTSX-B) and Skorpion IP routers (EIGR-E) to enable seamless BACnet/IP communication across subnetted networks and provide secure remote access for multiple buildings.
The BASRTSX-B routers include a Broadcast Distribution Table (BDT) capable of storing the IP addresses and subnet masks of up to 50 BBMD peers. This functionality enables BACnet/IP broadcast traffic to be shared across multiple IP subnets and geographically separated buildings.
In the application note's example, the system consists of three buildings: Building A, Building B, and Building C. Building A contains a BASV-3 graphical supervisor responsible for monitoring and managing controllers located in Building A as well as in Buildings B and C. A BASRTSX-B in Building A is configured as the primary BBMD for its local subnet.
To enable inter-building communication, the BASRTSX-B in Building A includes in its BDT the public IP addresses of the BBMD partners located in Buildings B and C. This configuration allows BACnet broadcast messages to be properly distributed between all participating subnets.
Within each building, the BASRTSX-B routes traffic between the BACnet MS/TP and BACnet/IP networks while also performing BBMD functions to forward broadcast messages to remote buildings. The topology can be expanded to include additional remote sites by simply adding their corresponding BBMD entries to the BDT.
With proper BBMD configuration and BDT entries:
- BACnet broadcast messages are forwarded as direct messages across subnets.
- Devices in Buildings B and C become discoverable from Building A.
- The BASV-3 supervisor in Building A can discover, monitor, and manage all controllers across the three buildings.
This configuration provides a scalable and efficient method for connecting multiple remote buildings over BACnet/IP using BBMD, while maintaining proper broadcast distribution and device discovery across routed IP networks.
For detailed information, read the Application Note: Remote Access Configuration for Multiple Buildings.
For product information, visit the the BASrouterSX and the Skorpion Gigabit IP Router webpages.