Easy BACnet
What do the units on a BACnet point mean?
Updated 11 October 2026
Analog BACnet points carry a Units property, a
standard code that says what the number means. A Present_Value of
55.0 on AHU-1 SA-T is just a number; with
Units = degrees-Fahrenheit it's 55 °F supply air. The standard fixes
the list of codes, so the same code means the same thing on every brand. Easy BACnet reads
the code and shows a short name next to the value (°F, % RH, CFM).
What the Units property is
Analog Inputs, Outputs and Values all have a Units property alongside
Present_Value. It holds an enumerated code from the BACnet standard, for
example 64 for degrees-Fahrenheit, 62 for degrees-Celsius, 58 for inches-of-water, 84 for
cubic-feet-per-minute and 98 for percent. Binary and multi-state objects have no
Units property at all; their meaning comes from their states.
Easy BACnet reads the code and shows a readable label in the Units row of the point
screen, so RM-214 ZN-T reads as 72.4 with units °F. If a
device returns a code the app doesn't have a name for, you'll see it as “units N”
with the raw number, which you can look up in the standard.
Units you'll see most
| Category | Typical units | Seen on |
|---|---|---|
| Temperature | °F, °C | Zone, supply, return, mixed, outdoor air; water temps; setpoints |
| Humidity | % RH | Zone and duct humidity, outdoor air |
| Air pressure | in of water, Pa | Duct static, filter DP, building static |
| Water pressure | psi, kPa | Loop DP, pump discharge |
| Air flow | CFM, L/s | VAV boxes, outdoor air stations |
| Water flow | GPM, L/s | Chilled and hot water loops |
| Percent | % | Damper and valve commands, VFD speed |
| Power and energy | kW, kWh, A, V | Meters, VFDs |
| Air quality | ppm | CO2 sensors |
| Time | hours, minutes, seconds | Runtimes, delays, timers |
No units is normal for some points. Counters, ratios, mode indexes and
some setpoint AVs carry no-units. The app shows those with a blank unit. It
doesn't mean anything is broken.
When the units look wrong
- A zone temp around 22 where you expected 72. The controller is working in °C. Check the Units label; the value is probably fine.
- The head-end shows °F but the controller says °C. Many front ends convert units on display, so the graphic and the raw BACnet value can differ. The app shows what the controller actually holds.
- The label doesn't match the point. AVs created during programming
are sometimes left at a default unit, so a static pressure setpoint might say
no-unitsor even °F. Go by the point name and the value, and tell whoever programmed the system.
Units in an export
When you export a points list, the spreadsheet has a Units column next to Present Value, so whoever receives it can read “55.0 °F” instead of guessing what 55 means.
Check it on your own network. Easy BACnet is a free Android app that finds BACnet IP devices and reads their points in a couple of taps.
Get it on Google Play