External representations (Brick v1.3)

Open-FDD models Brick points with Brick’s ref schema so software can discover how each point maps to external systems (BACnet and timeseries storage) using:

• ref:hasExternalReference
• ref:BACnetReference
• ref:TimeseriesReference

Open-FDD keeps legacy ofdd:* BACnet fields for compatibility, but ref:* is the preferred representation.

---

What Open-FDD emits

For each point in config/data_model.ttl:

• A timeseries reference:
  • a ref:TimeseriesReference
  • ref:hasTimeseriesId "<external_id>"
  • ref:storedAt "<postgresql://host:port/db/timeseries_readings>"
• A BACnet reference when BACnet addressing is known (bacnet_device_id + object_identifier):
  • a ref:BACnetReference
  • bacnet:object-identifier "<object-type,instance>"
  • optional bacnet:object-name "<name>"
  • bacnet:objectOf <bacnet://<device_instance>>
  • brick:BACnetURI "bacnet://<device>/<object>/present-value"

---

Example

:pt_123 a brick:Zone_Air_Temperature_Sensor ;
    rdfs:label "ZoneTemp" ;
    ref:hasExternalReference [
        a ref:BACnetReference ;
        bacnet:object-identifier "analog-input,3" ;
        bacnet:object-name "BLDG-Z410-ZATS" ;
        brick:BACnetURI "bacnet://123/analog-input,3/present-value" ;
        bacnet:objectOf <bacnet://123>
    ] ;
    ref:hasExternalReference [
        a ref:TimeseriesReference ;
        ref:hasTimeseriesId "ZoneTemp" ;
        ref:storedAt "postgresql://localhost:5432/openfdd/timeseries_readings"
    ] ;
    brick:isPointOf :eq_ahu_1 .

---

SPARQL discovery pattern

Use this to enumerate all external references and their types:

PREFIX ref: <https://brickschema.org/schema/Brick/ref#>
SELECT ?point ?rep ?type WHERE {
  ?point ref:hasExternalReference ?rep .
  ?rep a ?type .
}

BACnet-only references:

PREFIX ref: <https://brickschema.org/schema/Brick/ref#>
PREFIX bacnet: <http://data.ashrae.org/bacnet/2020#>
SELECT ?point ?oid ?dev WHERE {
  ?point ref:hasExternalReference ?rep .
  ?rep a ref:BACnetReference ;
       bacnet:object-identifier ?oid ;
       bacnet:objectOf ?dev .
}

Timeseries-only references:

PREFIX ref: <https://brickschema.org/schema/Brick/ref#>
SELECT ?point ?tsid ?store WHERE {
  ?point ref:hasExternalReference ?rep .
  ?rep a ref:TimeseriesReference ;
       ref:hasTimeseriesId ?tsid ;
       ref:storedAt ?store .
}