Technical Trade SchoolBAS-400 developer-series
BAS-407
Ten concept and evidence figures

BAS-407 Visual Aid Library

Figure-use rule

Each figure is an orientation and reasoning aid, not a project drawing. Learners must pair it with the current sequence, point list, wiring/piping documents, manufacturer instructions, and as-found evidence.

Figure 1 — Commissioning process, intent, roles, and test authority critical

Normal-rule anchor

The person who writes or corrects code does not automatically have authority to accept it; roles and evidence remain distinct.

Case overlay

The programmer is asked to sign acceptance for an AHU sequence before the owner witness attends.

Calculation/evidence callout: Reconcile requirements, test steps, roles, witnesses, acceptance authority, and unresolved items.

Figure 2 — Readiness, safety, prerequisites, and baseline critical

Normal-rule anchor

Testing an unready system creates misleading failures and risk; unmet prerequisites are evidence, not pressure to proceed.

Case overlay

A functional test is scheduled while TAB is incomplete, freeze conditions exist, and the latest program backup is missing.

Calculation/evidence callout: Score prerequisite completion, identify critical blockers, and calculate available test window against stabilization and restoration time.

Figure 3 — Point-to-point checkout, scaling, identity, and proof critical

Normal-rule anchor

Point checkout proves the entire signal or command chain; seeing a value change on one screen does not prove identity, scaling, or physical action.

Case overlay

Two room sensors are swapped in software and a damper output changes on screen but not at the actuator.

Calculation/evidence callout: Calculate scaling, error, tolerance, percent span, command/feedback difference, and point completion/defect counts.

Figure 4 — Command priority, overrides, safeties, release, and restoration critical

Normal-rule anchor

A test is incomplete until every software and physical temporary state is explicitly reconciled and normal control is proven.

Case overlay

A valve remains open after a test because the command was released at one priority but another override remains active.

Calculation/evidence callout: Reconcile every active priority, local/manual state, temporary account, alarm inhibit, jumper, and expected normal value before closeout.

Figure 5 — Loop performance, tuning, disturbance, and acceptance critical

Normal-rule anchor

Tune only after sensor, final element, direction, range, authority, and upstream process are verified; trend evidence must span disturbance through recovery.

Case overlay

A static-pressure loop overshoots after a setpoint step while one damper is mechanically stuck and the fan minimum is too high.

Calculation/evidence callout: Calculate error, overshoot, settling time, oscillation period, percent saturation, and acceptance-band duration.

Figure 6 — Modes, states, transitions, schedules, and restart tests critical

Normal-rule anchor

Steady operation in one mode does not prove transition logic; failures often live at startup, shutdown, overlap, timeout, and restart boundaries.

Case overlay

An AHU restarts into occupied cooling after a brief outage even though a freeze trip remains latched.

Calculation/evidence callout: Measure transition time, dwell, timeout, recovery, and schedule alignment against the test tolerance.

Figure 7 — Safeties, failure modes, fallback, and negative testing critical

Normal-rule anchor

Critical negative tests must be planned with qualified roles and safe simulation methods; software testing cannot replace required device or life-safety acceptance.

Case overlay

A simulated supply-air sensor failure drives a fallback setpoint but suppresses the alarm and leaves economizer enabled.

Calculation/evidence callout: Calculate time to safe state, alarm delay, retry count, fallback limits, and recovery time.

Figure 8 — Integration, end-to-end timing, data quality, and external systems critical

Normal-rule anchor

An integration point is accepted only when identity, units, state meaning, authority, quality, timing, physical response, and owner are proven end to end.

Case overlay

A chiller enable reaches the gateway but returns a delayed run status in a different enumeration and the alarm timestamps disagree.

Calculation/evidence callout: Calculate latency, clock offset, update interval, stale threshold, mapping coverage, and loss/recovery duration.

Figure 9 — Issues, severity, correction, retest, witness, and acceptance critical

Normal-rule anchor

A cleared symptom is not closure; the corrected mechanism, changed case, regression scope, restoration, and authorized acceptance must be documented.

Case overlay

A fan-proof defect is corrected by changing delay logic, but no test verifies real loss of proof or restart behavior.

Calculation/evidence callout: Reconcile open, corrected, retested, accepted, deferred, and rejected issues; no critical issue can be averaged away.

Figure 10 — Turnover, changed-case defense, and systems manual critical

Normal-rule anchor

Turnover artifacts must be current, reproducible, appropriately protected, and usable by the people who inherit the system; a quiz score cannot compensate for a critical safety, identity, evidence, or restoration failure.

Case overlay

The accepted program differs from the archived version, operator training uses an old graphic, and the changed case introduces one swapped point and one unrelated mechanical defect.

Calculation/evidence callout: Compare revisions/checksums, required versus delivered artifacts, restore-test status, training task success, changed-case evidence, and open ownership.