This simulator models a supervisory Building Management System (BMS) — sensors that measure, controllers that act locally, and a network that reports to and receives commands from a supervisory workstation. Five tabbed sections take you from running the building operations to inspecting the points/network layer, a fault-injection commissioning lab, how-it-works reference material and a 12-question knowledge check.
• Operations (01): a 3D building/plant view with Building view, Plant view, Auto orbit and camera controls; Play/step through simulated time (+60 seconds per step); adjustable outdoor temperature, sun load, occupant count and a manual override slider on the zone loop. • Points & network (02): a supervisory point list, live network transactions log and a command-priority demonstrator — issue a ReadPropertyMultiple poll, Write at priority 8, or Relinquish (write NULL) to release that priority level and reveal the next-highest command underneath. • Commissioning lab (03): fault injection and hardwired interlocks, including a freezestat trip with a persistent latch that requires releasing the fault input AND pressing Reset frost latch; a historian with exportable trend CSV; an event log with an Acknowledge events action; and a 12-check automated commissioning bench. • How it works (04): reference material on the control loop, the communication path and scope/assumptions. • Knowledge check (05): a 12-question quiz on supervisory outages, command priority arithmetic, alarm acknowledgment vs. repair, sensor bias and economizer control. • A guided tour button steps through every interactive component with contextual explanations.
Local controllers keep running their sequences autonomously even during a supervisory network outage — the supervisor only loses fresh telemetry and command access, not the physical control loop itself. The zone temperature loop uses proportional control with a minimum damper opening, which is why room temperature can settle slightly above a cooling setpoint even under steady conditions — a simplified but realistic reflection of proportional-only control.
Command priority follows the BACnet-style convention where lower priority numbers win: a priority-8 command of 80% beats a priority-16 command of 40%, regardless of magnitude. Writing NULL at a priority level relinquishes that operator's claim entirely rather than merely zeroing it out — a written 0% is still an active command that continues to win at its priority level.
The freezestat interlock is hardwired and independent of the supervisory network: once tripped, it latches and will not clear just by removing the trip condition — you must release the fault input and separately press Reset frost latch, mirroring how real safety interlocks require a deliberate operator reset rather than auto-clearing. Acknowledging an alarm only records that an operator has seen it; it does not repair the underlying physical cause, which is why the commissioning lab treats acknowledgment and repair as distinct actions to test your troubleshooting instincts.
A stale point (old timestamp) can still show a plausible-looking numeric value, which is why the lab emphasizes checking a point's freshness and network quality, not just its displayed number, when diagnosing a fault. The economizer logic here uses a simplified dry-bulb comparison between outdoor and return air; real sequences may also consider humidity and other limits.
Local controllers continue operating their sequences autonomously — an HVAC zone loop or air-handler sequence does not stop just because it loses contact with the supervisory workstation. What is lost is fresh telemetry and the ability to issue new commands from the supervisor until communication is restored.
Lower priority numbers have greater precedence. A command written at priority 8 wins over a command written at priority 16, regardless of which value is numerically larger. Writing NULL at a given priority relinquishes that command entirely, which can reveal a lower-priority (higher-numbered) command underneath rather than leaving the point at zero.
Acknowledging an alarm is an event-state action — it records that an operator has seen and is aware of the alarm. It does not change the underlying physical condition that caused it. Repairing the fault is a separate, physical action, which is why the commissioning lab tests both skills independently.
This lab models a simplified zone control loop with proportional-only control and a minimum damper opening. Proportional control characteristically needs some steady-state error to keep delivering the necessary control output, so a small, persistent offset above setpoint can be normal behavior rather than a fault.