BACnet Networks for NK823x DMS Applications

BACnet Network

On IP infrastructures applying UDP services, a BACnet network (BACnet/IP) consists of one or more IP subnets. All networked units are BACnet devices and must have a unique Device Identifier. The Desigo CC Server or FEP (represented by the BACnet driver) are also BACnet devices.

BACnet Addressing

The BACnet addressing is based on the instance number, the BACnet Device identifier (a value between 0 and 4194303). The instance number configured in Desigo CC for BACnet panels must match the BACnet Device ID configured in the engineering tool of the panels.

BACnet Interfaces

When a BACnet interface (for example, the NK823x Ethernet Port) is used to integrate non-BACnet panels, both the interface and the connected panels have assigned a unique instance number at Desigo CC level.

BACnet Stack Protocol Service

The BACnet Stack Protocol Service (BACstack) is the driver that handles the network communication. The BACstack service handles a physical port for every physical driver.

BBMD and Foreign Device

A BACnet network with a single IP subnet network allows all BACnet devices to communicate among them without any additional configuration.

A BACnet network comprising multiple IP subnets requires IP routing services—provided by standard IP equipment—as well as additional BACnet routing services, which can be provided by two different mechanisms:

• BACnet Broadcast Management Device (BBMD). BBMD devices handle the BACnet broadcast messages across multiple IP subnets. You must configure one BBMD per IP subnet and make BBMDs across subnets aware of each other.
• Foreign Device. A Foreign Device connects a single device from a separate IP subnet to the BBMD to communicate with the entire BACnet subnet.

BACnet Broadcast Message Routing

The management station and the NK823x can act as a BBMD or as a Foreign Device to manage the communication across multiple BACnet/IP subnets.

BBMD

The Broadcast Distribution Table (BDT) must include the IP addresses of all subnet units acting as BBMD.

NOTICE

There must be one and only one BBMD for each subnet. Two BBMDs in the same subnet can cause communication problems.

Foreign Device

You need to register the Foreign Device to the IP address of a subnet unit acting as BBMD. The unit acting as BBMD must be enabled to manage the Foreign Device Table (FDT).