BACnet/IP

BACnet is the standard protocol of building automation (ISO 16484-5). Each device holds objects (analog inputs, binary outputs, schedules, trend logs and more), and each object has properties such as its present value, units and status. BACnet/IP (Annex J) carries it over UDP port 47808, with BBMDs and routers joining networks across subnets.

Where you meet it

• HVAC controllers, chillers, air handlers and VAV boxes
• Lighting, access control and fire panels
• Building energy meters and building management systems (BMS)

Quickstart

From the command line

Download bacnetctl from GitHub Releases, then:

# Which devices are on this network?
bacnetctl discover

# Its point list: every object with value, unit, status and description
bacnetctl objects --device 192.168.1.20 --values

# One value
bacnetctl read --device 192.168.1.20 analog-input:1 present-value

# Watch two points change, until Ctrl-C
bacnetctl monitor --device 192.168.1.20 analog-input:1 binary-input:3

# Override a setpoint at operator priority, then hand it back
bacnetctl write --device 192.168.1.20 analog-value:1 present-value 22.5 --priority 8
bacnetctl release --device 192.168.1.20 analog-value:1 --priority 8

Objects are written as type:instance (analog-input:1, or ai:1) and properties by name (present-value, or pv).

From Go

go get github.com/otfabric/go-bacnet@latest

Discover devices and print their names:

package main

import (
  "context"
  "fmt"
  "log"
  "time"

  "github.com/otfabric/go-bacnet"
  "github.com/otfabric/go-bacnet/client"
)

func main() {
  c, err := client.New() // binds UDP port 47808
  if err != nil {
    log.Fatal(err)
  }
  defer c.Close()

  ctx := context.Background()
  devices, err := c.Discover(ctx, client.DiscoveryOptions{Window: 3 * time.Second})
  if err != nil {
    log.Fatal(err)
  }
  name := bacnet.PropertyReference{Identifier: bacnet.PropertyObjectName}
  for _, d := range devices {
    val, err := c.ReadProperty(ctx, d.Target(), d.DeviceID(), name)
    if err != nil {
      fmt.Printf("device %d at %s: %v\n", d.Instance, d.Address, err)
      continue
    }
    fmt.Printf("device %d at %s: %s\n", d.Instance, d.Address, val.Character.Value)
  }
}

What go-bacnet supports

Interoperability

bacnet-interop provides Dockerized devices from BACnet Stack (C), BACpypes3 (Python), BACnet4J (Java), System.IO.BACnet (C#) and Worldiety (Go), including BBMD and routed-network scenarios.