Every BAS Looks Different, Until You See the Pattern

Alex Khachaturian
Jul 7
2 min read

Updated: Aug 25

I first got exposed to a new BAS around year two of my journey.

At the time, I’d been working primarily with Andover (now Schneider Electric), and we were replacing old Allen-Bradley and Johnson Metasys systems. Everything looked different. The tools. The logic. The programming style.

But I had the luck of being surrounded by some very sharp technicians.

They didn’t just show me how to use the new system, they explained what was really going on underneath. The principles. The patterns. The why.

Once I grasped those, I realized something that changed the way I saw every job afterward:

The platforms change, but the core concepts stay the same.

And once you understand that, you stop getting intimidated by new systems. You start solving them.

The Core Truth: BAS Is Just Logic on Top of I/O

Every building automation system is made of the same components, no matter the brand:

Inputs: temperatures, pressures, contacts, statuses
Outputs: valves, dampers, relays, fans
Logic: the rules that say "If X, then Y"
Schedules: when things should happen
Alarms/Overrides: what happens when things go wrong (or manual)

Everything else? UI skin. Database structure. Fancy graphics. Labeling quirks.

But the bones are always the same.

What Changes; and What Doesn’t

What Changes What Stays the Same Programming syntax (block vs line vs UI) Control logic itself (PID, enable/disable) Naming conventions Point types: AI, AO, BI, BO, schedules Graphics and navigation System flow: AHU > VAV > Zone > Reheat Database structures Input/output mapping and relationships Communication tools (BACnet/IP, MSTP, etc) Need to understand device addressing, routing

Real BAS Skill Isn’t System-Specific

It's not about memorizing buttons. It’s about understanding behavior.

The true skill is:

Reading a sequence and mentally mapping it
Diagnosing failures by tracing signal flow
Linking hardware to logic
Grasping control intent, no matter the badge on the software

If you can wire, commission, and program an AHU in Niagara, you can learn to do it in Alerton, Distech, Siemens, Reliable, or Johnson. The tools change. The thinking doesn’t.

Want to Become Unstoppable?

Here’s how you build cross-platform fluency:

Stop chasing tricks. Learn principles.
Build logic literacy. Know the patterns before the interface.
Ask better questions. What’s this system trying to do? What are the dependencies?
Translate across brands. Rebuild a sequence from one system in another. Even on paper.
Teach others. If you can explain the logic without naming the platform, you understand it.