BACnet Engineering Units Decoder BACnet

The full BACnet Units enumeration (0–254)

Every standard value of the Units property, ascending by number. Click a value to copy it. Symbols in parentheses are searchable too.

Imported from bacnet-stack's BACnetEngineeringUnits enum (the de-facto machine-readable form of the ASHRAE 135 Units enumeration, which is paywalled) — retrieved 2026-07-12: 255 standard values, 0–254. The field-common rows carry the curated names and symbols shared with the Object Reference; the long-tail rows use bacnet-stack's spelling and should be confirmed against the standard for exact wording. Values 256 and up are the proprietary/vendor range — no assigned name here.

What the Units property is

Every analog object carries a Units property (117) that says what its Present_Value means — a number without a unit is just a number. BACnet stores it as an enumeration: rather than send the string "degrees-Celsius" on the wire, the device sends the integer 62, and the reading client looks the name up. That keeps messages small and language-neutral, at the cost of one indirection — which is exactly the indirection this page removes.

The enumeration is grouped loosely by domain — temperature in the low 60s, pressure in the 50s, flow in the 80s, electrical near the start — but the numbers are assigned in historical order within each edition, so there is no arithmetic to it. You either know it or you look it up.

Standard and proprietary ranges

Values 0–255 are ASHRAE's to assign, and the current standard defines names through 254 (255 is a reserved ceiling). A device reporting a units value in that range but showing no name usually means the client's database predates the value — not that the number is wrong.

256–65535 is the proprietary/vendor range, the same idea as the vendor-specific object types on the Object Reference: a manufacturer may define a unit its own equipment understands. A number there has no standard meaning, so the answer lives in the vendor's documentation — and the Vendor ID lookup tells you whose documentation to open.

Where you see raw units values

Three places, usually: a property sheet that lists Units as a number instead of resolving it, a trend or point export whose columns carry the enum rather than the label, and a decoded packet in Wireshark where the Units tag shows the bare Unsigned integer. In all three it is the same number — paste it above.