Best Practices

This section describes the best practices for various BACnet Operations.

For BACnet Clients (e.g. Workstations)

1. BACnet Client Startup Procedures are fairly complex, and deserve a section of their own.
2. BACnet Workstations require a Device Instance number, and require a Device Object to conform to the BACnet Specification. It is common practice, and relatively harmless, not to include either the Device Object in Operator workstations.

BACnet Objects

Priority Arrays

Routers

Do issue I-Am-Router on startup

Who-Is and I-Am

• A single page entry for Who-Is/I-Am best practices is here.
• Do not issue I-Am on startup. Although the specification calls for this, large networks (thousands of devices) on power-up can generate a flood of I-Ams. Devices are still discoverable by the BACnet client issuing a Who-Is, to which the device can respond with an I-Am.
• I-Ams as a response to a Who-Is should be directed at the device which issues the Who-Is. Although a broadcast I-Am response is legal, a directed one reduces the amount of broadcast traffic on the networks.
• Who-Is requests should be directed to smaller and smaller sections of the valid address space. A Who-Is with no range limits, or a very large range, could generate thousands of I-Ams, which can easily flood Routers, IP Stacks etc.

IP Address assignment

Static IP Addresses DHCP

MSTP

Auto Addressing Auto Baud Baud Rate