Learning the Language
Lesson 1.4
Section 1: Point Naming
When you first open a program on an unfamiliar controller, you are going to see a list of point names that looks like someone fell asleep on a keyboard. CCLA_T. CWMUV_C. WWR_T. SF_S. Don't panic. There is a system to this.
Most point names are built from three parts:
- A prefix that identifies the system or equipment: CW for condenser water, ZN for zone, DA for discharge air, OA for outdoor air
- A descriptor that identifies what the point actually is: T for temperature, P for pressure, F for flow, SP for setpoint
- A suffix that identifies the point's function: C for command, S for status, A for alarm
Walk through a real one. CWMUV_C. CW = condenser water. MU = makeup. V = valve. C = command. It's telling the condenser water makeup valve to open or close.
Section 2: Common Suffixes (JCI Convention)
- -T: Temperature
- -H / -RH: Humidity (relative humidity)
- -P: Pressure
- -F: Flow
- -Q: CO2 / Air Quality
- -SP: Setpoint
- -C: Command, binary (open/close, on/off)
- -S: Status (what something is actually doing)
- -O: Output, analog (0-100%, 0-10V)
- -A: Alarm
- -H: High limit
- -LL: Low limit
These aren't universal. Use this as a starting point, not a rulebook.
Section 3: Decode the Point (Examples)
- CCLA_T: Cooling coil leaving air temperature
- WWR_T: Well water return temperature
- CWMUV_C: Condenser water makeup valve command
- ZN_SP: Zone temperature setpoint
- SF_S: Supply fan status
- DA_T: Discharge air temperature
Not all sites follow any naming convention you can reverse-engineer. Some use numeric equipment codes. When you hit names like that, ask for the points list or the sequence of operations. There is almost always a key.
# TERMINAL UNIT SERIES