BOOT-BAC 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.
Normal-rule anchor
BACnet defines interoperable data and services, but project requirements and implemented capabilities determine what two devices can actually do together.
Case overlay
A controller is BACnet listed, yet the required schedule write and event enrollment workflow fails between vendors.
Calculation/evidence callout: Build a requirement-to-capability coverage matrix and calculate confirmed, unsupported, ambiguous, and untested coverage percentages.
Normal-rule anchor
A plausible Present_Value is not point truth when identity, units, reliability, override, timestamp, or physical corroboration is wrong.
Case overlay
A discharge-air value looks normal on a graphic while Reliability is fault, units are wrong, and the sensor is disconnected.
Calculation/evidence callout: Convert units, calculate scaling/error and age, and compare independent evidence to acceptance tolerance.
Normal-rule anchor
A successful write response proves protocol acceptance, not effective priority, physical action, safe process response, or restoration.
Case overlay
An AO accepts a write but does not move because a higher priority remains active; the operator later sees an unexplained override.
Calculation/evidence callout: Calculate effective priority, command/proof error and timeout, then reconcile every introduced priority or Out_Of_Service state to zero.
Normal-rule anchor
Identity exists at several layers; a device may be reachable by IP while BACnet discovery or routed services fail.
Case overlay
Local Who-Is works, remote discovery fails, and two routers advertise the same BACnet network.
Calculation/evidence callout: Calculate subnet membership, broadcast boundaries, FDR lifetime margin, hop/path inventory, and duplicate coverage.
Normal-rule anchor
BACnet/SC protects transport relationships; certificate lifecycle, identity, authorization, product support, operations, and recovery still require governance.
Case overlay
A node stops reconnecting after certificate renewal while time is wrong and an old trust anchor remains on one hub.
Calculation/evidence callout: Calculate certificate-life and renewal windows, time error, node/hub capacity from supplied limits, and recovery coverage.
Normal-rule anchor
RS-485 electrical integrity and MS/TP link configuration are separate but interacting evidence layers; neither is proven by seeing one device online.
Case overlay
A trunk works with two devices and fails after a controller is added through a long star branch with reversed polarity.
Calculation/evidence callout: Calculate segment loading and stub/length ratios from supplied limits, expected end-to-end termination resistance, token-cycle effects, and error rate.
Normal-rule anchor
Latency must be traced through the whole service path; changing baud or timeouts blindly can hide rather than fix the cause.
Case overlay
Zone values update every 90 seconds after a front-end polling change, but CRC errors remain low.
Calculation/evidence callout: Calculate token-cycle and update-time estimates, requests per minute, retry percentage, latency distribution, and before/after load.
Normal-rule anchor
A large capture is not automatically useful evidence; placement, time quality, question, filter, scope, and sanitization determine value.
Case overlay
A capture shows repeated retries, but it was taken on the wrong VLAN and the timestamps do not match controller logs.
Calculation/evidence callout: Calculate capture duration/size, request-response latency, retry/error rate, and clock offset before correlating sources.
Normal-rule anchor
Configuration existence does not prove delivery, acknowledgement, persistence, restart behavior, time quality, or operator usefulness.
Case overlay
An alarm appears locally but not at the workstation after restart; trend samples are duplicated around a time correction.
Calculation/evidence callout: Calculate COV/reporting volume, alarm delay, schedule precedence, sample storage/retention, missing/duplicate rates, and time skew.
Normal-rule anchor
Interoperability is a tested use-case claim, not a brand-wide claim; gateways introduce translation, lifecycle, performance, and ownership boundaries. A system is not commissioned when only discovery and point reads pass; functional outcomes, failures, restart, recovery, documentation, and restoration are required.
Case overlay
A Modbus gateway maps an enumerated state as analog, reverses byte order on energy, and drops quality on communications loss. Changed-capstone condition: All devices appear online, yet one priority remains, two notifications are unverified, and the final router configuration was not backed up.
Calculation/evidence callout: Calculate map coverage, scaling/byte-order results, update latency, error handling coverage, and untested combinations. Reconcile planned/executed/passed/failed/retested tests and calculate critical coverage, issue closure, temporary-state closure, and residual risk.