bacnet

README

Smart Core BACnet/IP driver

This package implements integration between BACnet/IP and Smart Core. The driver uses a Vanti fork of gobacnet maintained on the write branch.

The driver interprets config and sets up connections to BACnet devices and associates BACnet objects with Smart Core traits and properties.

There's a definitive sample config file in config/testdata. The driver only supports JSON (not json5), but the json5 helps with documenting the properties available.

Sample BACnet driver config

{
  "type": "bacnet", "name": "MyDriverImpl",
  "devices": [
    {
      "id": 10002,
      "objects": [
        {"id": "BinaryValue:1", "trait": "smartcore.traits.OnOff"}
      ]
    }
  ],
  "traits": [
    {
      "name": "thermostat", "kind": "smartcore.traits.AirTemperature",
      "setPoint": {"device": 10002, "object": "AnalogInput:0"},
      "ambientTemperature": {"device": 10002, "object": "AnalogOutput:0"}
    }
  ]
}

BACnet - Smart Core Mapping

The driver does not make any assumptions about which objects implement which traits. If an object does map well to the semantics of a trait then you can specify this in the devices.objects.trait property as shown in the example above. If an Object->Trait mapping isn't implemented it can be added into the adapt package where each go file contains mappings from that BACnet object type into relevant traits.

More complicated mappings from multiple objects to a single named trait are configured via the traits config property and the merge package.

The driver also publishes a non-Smart Core gRPC API described in bacnet.proto that provides low level access to BACnet services like ReadProperty and WriteProperty against configured devices.

BACnet - Destination Network Addressing

One project worked on, that uses this driver had the following setup:

controller-1/ DeviceID 1100
├─ fcu-1 DeviceID 1111
├─ fcu-2 DeviceID 1112
controller-2/ DeviceID 1200
├─ fcu-3 DeviceID 1211
├─ fcu-4 DeviceID 1212

The controllers were BACnet/IP devices, that connected to FCUs and other field devices over BACnet MS/TP (RS485). The controllers were all on the BMS VLAN, and this driver was running on a separate SC VLAN with UDP traffic on port 0xBAC0 allowed to the BMS VLAN; broadcast traffic wasn't supported/set-up.

It was noticed that YABE on the BMS VLAN would discover all controllers and all FCUs, and be able to make requests to specific FCUs. However, from the SC VLAN, any request to a specific FCU device ID, sent to a controller IP address, would respond with an error unknown-object.

It was discovered that a destination network and address must also be specified in the request. This ends up in the NPDU packet, and can be inspected with Wireshark. In this particular case the information we need was (partially) encoded into the device IDs: FCU device ID 1211 was on destination network 50012, and had address 11; this could only be found out because we had YABE working on VLAN, else we'd have had to ask for extra information. Also, because they had their software auto-assign IDs, which made the pattern I suppose.

TL;DR

For some BACnet requests you may need to set a destination network and address, as well as IP:port, and device ID. This is configured by the Comm#Destination field.

Documentation

Index

• Constants
• Variables
• func FindDevice(ctx context.Context, client *gobacnet.Client, device config.Device) (bactypes.Device, error)
• func Register(supporter node.Supporter)
• type Driver
  • func NewDriver(services driver.Services) *Driver
  • func (d *Driver) Clear()

Constants

const DriverName = "bacnet"

Variables

var Factory driver.Factory = factory{}

Functions

func FindDevice

func FindDevice(ctx context.Context, client *gobacnet.Client, device config.Device) (bactypes.Device, error)

func Register

func Register(supporter node.Supporter)

Register makes sure this driver and its device apis are available in the given node.

Types

type Driver

type Driver struct {
	*service.Service[config.Root]
	// contains filtered or unexported fields
}

Driver brings BACnet devices into Smart Core.

func NewDriver

func NewDriver(services driver.Services) *Driver

func (*Driver) Clear

func (d *Driver) Clear()