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BAS practice labs
Troubleshoot simulated equipment, networks and control programs before you’re standing in front of the real problem. Work an exercise with the tutorial, try it again on your own, then take a timed test and put your name on the leaderboard. Free exercises need no account; exercises marked Pro unlock when Pro launches.
Troubleshooting
Equipment, sensors, safeties and control loops. Find which layer broke.
- Controls troubleshooting BAS Diagnostic Simulator Twenty real faults from BAS Field Fundamentals. A live-looking graphic, a work order and a clock: ask, read the BAS, go to the equipment, then make the call on which layer broke. 20 field casesDampers, VFDs, sensors, safeties, pumps, alarms Scored cases Open the simulator →
- Control loops PID Tuning Lab Live HVAC loops on a trend: VAV airflow, discharge air, duct static, cascade and heat/cool pairs. Tune freely in the sandbox, or work thirteen loop faults where tuning is sometimes the answer and sometimes the trap: windup, wrong action, stiction, dead time, oversized valves. 13 loop faultsFree tuning sandbox SandboxTutorialPractice Open the PID lab →
Networks and protocols
BACnet/IP, MS/TP, Modbus and LonWorks, from the wire up.
- BACnet MS/TP and RS-485 MS/TP Trunk Lab A live trunk with a router and a string of controllers. Meter it (ohms powered down, idle volts, common mode), read the token pass in an MS/TP capture, and fix polarity, termination, bias, grounding, stubs, baud, MAC, Max Master and Max Info Frames faults. Then prove the whole trunk is healthy. 13 trunk faultsMeter, capture and settings TutorialPracticeFix and verify Open the MS/TP lab →
- BACnet/IP and IP networking BAS Network Lab Read BACnet/IP in a Wireshark-style capture window, then work IP problems from a Windows command prompt against a live site drawing: BBMDs, duplicate instances, wrong VLANs, firewalls, VPN routes and more. 16 capture scenarios17 network scenarios TutorialPracticeTest + leaderboard Open the network lab →
- Modbus/TCP and LonWorks IP-852 Modbus & LonWorks Capture Lab Find the one bad conversation in a mixed-protocol capture: Modbus exceptions, word order, scaling and gateways, LonWorks addressing, routers, heartbeats and SNVT scaling. 10 Modbus scenarios10 LonWorks scenarios TutorialPracticeTest + leaderboard Open the capture lab →
Programming
Block logic on any platform: execution order, priority, timers, sequences and porting.
Security
BACnet/SC, segmentation, remote access and site audits, from the field side.
- Cybersecurity · Defensive Security Audit Lab Walk a simulated building’s network, supervisor, controllers and remote access. Find the gaps (internet exposure, default and shared passwords, a flat network, forgotten remote tools, unpatched PCs, untested backups), choose fixes that don’t take the building down, and verify. 10 site auditsFix and verify TutorialPractice Open the audit lab →
- BACnet Secure Connect · Security BACnet/SC Capture Lab The Wireshark-style capture window, for encrypted BACnet. Learn the SC connection sequence, what you can read without keys and how to decrypt with a TLS key log, then find expired certificates, untrusted CAs, firewall drops, TLS inspection, idle timeouts, failover and duplicate VMACs. 11 capture scenariosKey-log decryption TutorialPractice Open the BACnet/SC lab →
The method behind every lab
Command, feedback and sensor value are not the same thing as reality: any layer can tell the one above it something that isn’t true. Every exercise trains the same habit. Trace down until the evidence stops agreeing.
The graphic says the fan is running. How do you know?
AHU-3 supply fan, traced one layer at a time.
- Graphic SF-3 status RUNNING Agrees with the command below it.
- Logic SF-3 cmd ON Agrees — occupied, safeties made.
- Network BI-7 present value active Agrees — fresh read, no fault flags.
- Equipment Supply airflow 0 CFM Broke here. The belt is off the sheave, but the motor’s no-load current still trips the current switch.
Every layer above it was reporting correctly.
How the labs work
Tutorial
The next click is outlined and each step is explained. Learn the tool before you need it on site.
Practice
Same fault, no outlines. Collect the findings yourself, with hints that cost points.
Test
Random faults, no hints, one answer each and a clock. Scores post under the name you enter.
Every lab comes from the books
The troubleshooting cases come from BAS Field Fundamentals; the captures, filters and Wireshark profile come from BAS Communication: A Field Reference; the logic lab comes from BAS Logic.
Every exercise
Free exercises open right away with no account. Exercises marked Pro unlock when BAS Field Reference Pro launches.
Diagnostic Simulator20 exercises · 5 free · 15 Pro
- The damper that says 100%Terminal unitsFree
- Run command, no fanAir handlersFree
- The drive that keeps faultingPlant and pumpsFree
- Cooling that runs and does nothingAir handlersFree
- The sensor that reads right at the sensorSpaces and sensorsFree
- The isolation room that passesSpaces and sensorsPro
- Humidity reading zeroSpaces and sensorsPro
- Proof says off, motor is runningFansPro
- Pump on, no pressurePlant and pumpsPro
- The economizer that isn'tAir handlersPro
- The freezestat that keeps trippingAir handlersPro
- Everybody is complainingAir handlersPro
- One zone, no neighboursTerminal unitsPro
- The loop that huntsAir handlersPro
- The average that isn'tSpaces and sensorsPro
- The valve that is closedTerminal unitsPro
- Commanded speed, actual speedAir handlersPro
- Airflow reads zeroAir handlersPro
- The alarm that cried wolfSpaces and sensorsPro
- Works in hand, not in autoPlant and pumpsPro
Network Lab33 exercises · 5 free · 28 Pro
- Who’s on the wire?BACnet capture analysisFree
- Question marks after a swapBACnet capture analysisFree
- One VAV won’t answerBACnet capture analysisFree
- Building C disappearedBACnet capture analysisPro
- Everything got slowBACnet capture analysisPro
- The controller that comes and goesBACnet capture analysisPro
- No address on the BAS networkIP networkingFree
- Answers ARP, ignores pingIP networkingFree
- Works locally, dead from HQIP networkingPro
- The ping that liedIP networkingPro
- The new building won’t routeIP networkingPro
- Plugged in, but on the wrong networkIP networkingPro
- Ping works, BACnet doesn’tIP networkingPro
- The setpoint that won’t stickBACnet capture analysisPro
- Points won’t importBACnet capture analysisPro
- Two routers, one network numberBACnet capture analysisPro
- Invisible on the wrong portBACnet capture analysisPro
- Moved to the data centerBACnet capture analysisPro
- The value that frozeBACnet capture analysisPro
- Shouting at an empty roomBACnet capture analysisPro
- The mask in the wrong placeBACnet capture analysisPro
- Offline, but answeringBACnet capture analysisPro
- The night shift scheduleBACnet capture analysisPro
- Discovery finds nothing, ping worksIP networkingPro
- The laptop that won’t listenIP networkingPro
- Somebody’s already on 47808IP networkingPro
- Out of the boxIP networkingPro
- It moved after the outageIP networkingPro
- The VPN that took the long wayIP networkingPro
- Slow, lossy, only one controllerIP networkingPro
- Both went darkIP networkingPro
- Discovery stops at the routerIP networkingPro
- Everything is slow and droppingIP networkingPro
Capture Lab20 exercises · 5 free · 15 Pro
- New meter, every point in faultModbusFree
- One meter behind the gateway is offlineModbusFree
- Chiller kW reads nonsenseModbusFree
- VFD feedback freezes, "device busy"ModbusPro
- Dashboard gets "connection refused"ModbusPro
- Boiler controller: illegal functionModbusPro
- Added points, whole device faultedModbusPro
- Setpoint writes snap backModbusPro
- Offline in the JACE, fine in the cloudModbusPro
- VFD flips between ok and faultModbusPro
- Replacement VAV never shows upLonWorksFree
- Relocated VAV: outputs work, writes time outLonWorksFree
- Space temp jumps between two valuesLonWorksPro
- Override button stopped starting the AHULonWorksPro
- Whole LON network feels sluggishLonWorksPro
- New floor router is ignoredLonWorksPro
- Floor 2 data arrives late or not at allLonWorksPro
- Building B dropped off after a firewall changeLonWorksPro
- Space temp reads over 2000 °FLonWorksPro
- IP traffic tripled after a router swapLonWorksPro
Block Logic Lab21 exercises · 7 free · 14 Pro
- The fan that won’t settleOrderFree
- Two pumps, one argumentOrderPro
- The damper that won’t listenArbitrationFree
- Latched, and still openArbitrationPro
- Preheat in AugustOmissionFree
- The reset that winsOmissionPro
- Spring afternoonThresholdFree
- Stage 2 never arrivesThresholdPro
- Which branch is live?ResidueFree
- October in JulyResiduePro
- Economizer changeoverBuildFree
- Two-stage cooling with lockoutBuildPro
- Occupancy override with a capBuildPro
- Freeze-protection interlockBuildPro
- Lead/lag pump rotationBuildPro
- Supply air temperature resetBuildPro
- The first hourCrossing overFree
- Upside-down switchesCrossing overPro
- The spare inputCrossing overPro
- Same numbers, different meaningCrossing overPro
- Drawn right to leftCrossing overPro
MS/TP Trunk Lab13 exercises · 5 free · 8 Pro
- One VAV dark after a ceiling jobWiringFree
- Everything past VAV-6 is offlineWiringFree
- Replacement controller never comes onlineConfigurationFree
- New VAV skipped in the token passConfigurationFree
- Two VAVs flash on and offConfigurationFree
- Whole trunk flaky after a router swapTermination and biasPro
- Three terminatorsTermination and biasPro
- Nothing at the far endTermination and biasPro
- Drops when the chiller startsWiringPro
- The added VAV on a spurWiringPro
- Values update slowly, writes time outPerformancePro
- Intermittent past VAV-9WiringPro
- Two faults, one trunkConfigurationPro
PID Tuning Lab13 exercises · 5 free · 8 Pro
- The VAV that huntsTuningFree
- Discharge air that never gets thereTuningFree
- Static pressure overshoot on startWindup and limitsFree
- Heating valve goes the wrong wayConfigurationFree
- The damper that jumpsMechanicalFree
- Windup while the fan is offWindup and limitsPro
- Derivative on a noisy sensorTuningPro
- The sensor forty feet downstreamProcessPro
- Oversized valveProcessPro
- Deadband too tightTuningPro
- Cascade backwardsCascadePro
- The minimum that won't let it closeWindup and limitsPro
- Heating and cooling fightConfigurationPro
BACnet/SC Capture Lab11 exercises · 5 free · 6 Pro
- What BACnet/SC looks like on the wireLearning BACnet/SCFree
- Offline since the first of the monthCertificatesFree
- The hub nobody can reachNetwork pathFree
- Refused at the doorNetwork pathFree
- The hub name that doesn’t resolveNetwork pathFree
- Signed by the wrong CACertificatesPro
- Every connection broke after the firewall upgradeNetwork pathPro
- Drops every few minutes, reconnects on its ownNetwork pathPro
- Everyone moved to the failover hubHubsPro
- Two controllers, one VMACHubsPro
- Still talking BACnet/IPMigrationPro
Security Audit Lab10 exercises · 5 free · 5 Pro
- The supervisor on the internetExposureFree
- Factory passwords on every controllerAccountsFree
- BAS on the office networkNetworkFree
- Everyone logs in as adminAccountsFree
- The remote support tool nobody remembersRemote accessFree
- The supervisor PC nobody patchesMaintenancePro
- The backup that won’t restoreMaintenancePro
- No logs, wrong clocksMaintenancePro
- The laptop that visits every siteMaintenancePro
- The always-on vendor VPNRemote accessPro