Plantroom Labs — technical notesNotes from Niagara Framework engineering: modules and drivers, bajaux widgets, PX graphics, station and controller work.https://plantroomlabs.com/feed.xml2026-09-30T00:00:00Zhttps://plantroomlabs.com/assets/favicon.ico?v=503bf7424a89https://plantroomlabs.com/assets/mark.svg?v=b3d8ec4a5542Plantroom Labshttps://plantroomlabs.com/What a Niagara oBIX Server Actually Exposeshttps://plantroomlabs.com/notes/what-an-obix-server-actually-exposes/2026-09-30T00:00:00Z2026-09-30T00:00:00ZThe mount point, the three verbs, the twelve lobby branches, the five that appear in no listing, and where the open alarms actually are.Auditing a Modbus or BACnet Claim Against the Codehttps://plantroomlabs.com/notes/protocol-document-versus-the-code/2026-09-30T00:00:00Z2026-09-30T00:00:00ZThe method behind a protocol-discrepancy audit: treat a documented default, range or address as a claim, then settle it against the code, twice.Letting an AI Agent Write to a Control Systemhttps://plantroomlabs.com/notes/letting-an-agent-write-to-a-control-system/2026-09-30T00:00:00Z2026-09-30T00:00:00ZA write to a station is a plant movement at a priority level, not a variable assignment. What has to be gated before a model gets the verb.What Niagara Does With the Modbus Address You Typehttps://plantroomlabs.com/notes/niagara-modbus-address-format/2026-09-29T00:00:00Z2026-09-29T00:00:00ZThe address field is a format plus a string, and the format defaults to hex. What each format does to the number, and where the boundaries fall through.Why a Modbus Network Sits at 95% Busy Timehttps://plantroomlabs.com/notes/modbus-poll-scheduling-and-busy-time/2026-09-29T00:00:00Z2026-09-29T00:00:00ZBusy time is the duty cycle of one poll thread per network, not host CPU. What it measures, where the time goes, and what actually brings it down.Why a BACnet Write Relinquishes on Its Ownhttps://plantroomlabs.com/notes/bacnet-write-relinquish/2026-09-29T00:00:00Z2026-09-29T00:00:00ZFallback is level 17, which is not a BACnet priority. What the driver sends when a point falls to it, and why the in slot sometimes changes nothing.Reading a LoRaWAN Payload Decoder Before You Trust Ithttps://plantroomlabs.com/notes/reading-a-lorawan-payload-decoder/2026-09-28T00:00:00Z2026-09-28T00:00:00ZEight things found by executing vendors' published JavaScript codecs, and what each one does to a Niagara point once the data lands.Reading an Unfamiliar MQTT Broker in a Buildinghttps://plantroomlabs.com/notes/reading-an-unfamiliar-mqtt-broker/2026-09-27T00:00:00Z2026-09-27T00:00:00ZA subscriber cannot list topics, the retain flag is how you tell a stored value from a live one, and a duplicate client ID disconnects someone else.What a PX Page Weighs, and the Hidden Gzip Switchhttps://plantroomlabs.com/notes/px-page-payload-and-gzip/2026-09-27T00:00:00Z2026-09-27T00:00:00ZA PX view ships about 2.3 MB of framework JavaScript before your graphic. Gzip is off by default, and /module/* bypasses the filter that would do it.Orphaned Niagara Modules: When the Vendor Is Gonehttps://plantroomlabs.com/notes/orphaned-third-party-niagara-modules/2026-09-27T00:00:00Z2026-09-27T00:00:00ZThe Marketplace storefront is gone and vendors are winding down. How to list which third-party modules a station depends on, and who owns each.What a BACnet Who-Is Sweep Finds, and What It Misseshttps://plantroomlabs.com/notes/bacnet-discovery-what-who-is-finds/2026-09-27T00:00:00Z2026-09-27T00:00:00ZWho-Is stops at the subnet, I-Am carries no device name, and an object list from a device that cannot segment has to be read one index at a time.3D Floorplan Graphics in Niagara PX Sheetshttps://plantroomlabs.com/notes/3d-floorplan-graphics-in-niagara/2026-09-27T00:00:00Z2026-09-27T00:00:00ZA 3D render is artwork made outside Niagara. What format it arrives in, what can bind to it, and why plan view wins for 200 zone temperatures.What a Niagara 5 Module Scan Actually Findshttps://plantroomlabs.com/notes/what-an-n5-module-scan-actually-finds/2026-09-26T00:00:00Z2026-09-26T00:00:00ZReading a module's bytecode against Java 25 gives a per-module answer. What it finds, what it cannot tell you, and the false alarms it avoids.What Java 25 Does to Niagara Module Permissionshttps://plantroomlabs.com/notes/niagara-module-permissions-on-java-25/2026-09-26T00:00:00Z2026-09-26T00:00:00ZNiagara's module permission model is built on Java's Security Manager. On a Java 25 JVM it cannot be installed, so the checks stop happening.Bringing LoRaWAN and MQTT Data Into a Niagara Stationhttps://plantroomlabs.com/notes/lorawan-and-mqtt-into-a-niagara-station/2026-09-26T00:00:00Z2026-09-26T00:00:00ZWhere abstractMqttDriver and jsonToolkit stop, and what LoRaWAN decoding, topic design, and store-and-forward buffering add on top.How to Build and Load a Custom Niagara 4 Modulehttps://plantroomlabs.com/notes/building-and-loading-a-custom-niagara-module/2026-09-26T00:00:00Z2026-09-26T00:00:00ZWhat a Niagara module actually is on disk, the two ways to build one, and the three Software Manager refusals that actually mean something.What Happens to Third-Party Modules Moving N4 to N5https://plantroomlabs.com/notes/n4-to-n5-third-party-modules/2026-09-25T00:00:00Z2026-09-25T00:00:00ZA module with no Niagara 5 build can stop the migrator outright, and one that has a build can still fail to load. What breaks, and why.JACE-8000 to JACE-9000: What the Licence Transfer Doeshttps://plantroomlabs.com/notes/jace-8000-to-jace-9000-licence-transfer/2026-09-25T00:00:00Z2026-09-25T00:00:00ZThe JACE 8000 to 9000 licence transfer, step by step: what it requires, what it does not include, and which parts cannot be undone.BAS or BMS: Where a Niagara Station Actually Fitshttps://plantroomlabs.com/notes/bas-or-bms/2026-09-25T00:00:00Z2026-09-25T00:00:00ZBAS and BMS mostly mean the same thing. The distinction worth tracking is single-vendor versus open — and where a Niagara station sits either way.One PX Sheet for Every AHU: Relative ORDshttps://plantroomlabs.com/notes/px-relative-ords/2026-09-23T00:00:00Z2026-09-23T00:00:00ZThe Px editor binds absolutely by default, which is why a graphic works for AHU-01 and nothing else. Relativised, one sheet serves the whole plant.Platform or Station: Two Connections, Two Sets of Loginshttps://plantroomlabs.com/notes/platform-versus-station/2026-09-23T00:00:00Z2026-09-23T00:00:00ZTwo processes, two Java VMs, two logins and two file trees — and most “it works in Workbench but not the browser” starts here.A JACE-8000 Has No Onboard I/O: Using the Nrio Driverhttps://plantroomlabs.com/notes/nrio-io-on-a-jace-8000/2026-09-23T00:00:00Z2026-09-23T00:00:00ZRemote IO-R modules on RS-485, one network per port, and the conversion list Workbench will happily let you get wrong.Why a Writable Point Ignores the Value You Sethttps://plantroomlabs.com/notes/niagara-writable-point-priority/2026-09-23T00:00:00Z2026-09-23T00:00:00ZSixteen priority inputs, two of them reserved for right-click actions, a fallback underneath, and a BACnet scheme wired to none of it.The Certificate on a New JACE, and Its Expiryhttps://plantroomlabs.com/notes/niagara-tls-certificates/2026-09-23T00:00:00Z2026-09-23T00:00:00ZEvery station starts with a self-signed certificate it generated itself. What that is good for, what it is not, and what breaks on the day it expires.Templates: Build the AHU Once, Deploy It Fifty Timeshttps://plantroomlabs.com/notes/niagara-templates/2026-09-23T00:00:00Z2026-09-23T00:00:00ZComponent, application and station templates do different jobs — and only one of them supports bulk deployment from a spreadsheet and upgrade in place.Tags, Dictionaries and the Licence You Needhttps://plantroomlabs.com/notes/niagara-tag-dictionaries/2026-09-23T00:00:00Z2026-09-23T00:00:00ZTagging is how a station describes itself to software that did not engineer it. Three kinds of tag, one namespace, and a licence feature that gates it.Niagara Schedules: Special Events and Master Copieshttps://plantroomlabs.com/notes/niagara-schedules-and-special-events/2026-09-23T00:00:00Z2026-09-23T00:00:00ZSpecial event priority is list order, a partly-filled special event falls back to the weekly schedule, and an imported schedule cannot be edited locally.Roles, Categories and the Grid Between Themhttps://plantroomlabs.com/notes/niagara-roles-and-permissions/2026-09-23T00:00:00Z2026-09-23T00:00:00ZNiagara permissions are a grid of category against level — which is why a user can log in successfully and still be told they have no access.Doing One Thing to Fifty Stations at Oncehttps://plantroomlabs.com/notes/niagara-provisioning-jobs/2026-09-23T00:00:00Z2026-09-23T00:00:00ZProvisioning runs platform tasks across a whole NiagaraNetwork from one Supervisor connection — and the obvious backup action is the wrong one.Why a Niagara Station Polls Too Slowlyhttps://plantroomlabs.com/notes/niagara-poll-rates-and-tuning-policies/2026-09-23T00:00:00Z2026-09-23T00:00:00ZSlow, Normal and Fast are three numbers you choose, and one default tuning policy applied to every point is the usual reason a station feels sluggish.What the Niagara MQTT Driver Will and Will Not Dohttps://plantroomlabs.com/notes/niagara-mqtt-driver/2026-09-23T00:00:00Z2026-09-23T00:00:00ZIt is licensed, it is capped below your licence, it is a client only, and its Discover button never contacts the broker.History Capacity on a JACE, and Lost Recordshttps://plantroomlabs.com/notes/niagara-history-capacity/2026-09-23T00:00:00Z2026-09-23T00:00:00ZThe default capacity is 500 records, the default name collides, and one setting decides whether a full history overwrites data or stops collecting.A Navigation Tree That Builds Itselfhttps://plantroomlabs.com/notes/niagara-hierarchies/2026-09-23T00:00:00Z2026-09-23T00:00:00ZHierarchies generate the nav tree from tags and NEQL queries instead of hand-placed nodes — and the cache hides your edits until you rebuild it.Conversion Links: What a Mismatched Wire Really Doeshttps://plantroomlabs.com/notes/niagara-conversion-links/2026-09-23T00:00:00Z2026-09-23T00:00:00ZLink a boolean to a numeric and Niagara inserts a converter with its own properties. Here is what each one assumes on your behalf.Authentication Schemes: Each Niagara User Picks Onehttps://plantroomlabs.com/notes/niagara-authentication-schemes/2026-09-23T00:00:00Z2026-09-23T00:00:00ZA station can run several login mechanisms at once, and the choice is made per user, not per station. What each scheme is actually for.Why an Alarm Never Reached Anybodyhttps://plantroomlabs.com/notes/niagara-alarm-routing/2026-09-23T00:00:00Z2026-09-23T00:00:00ZDetection, class and recipient are three separate objects in a Niagara station. An alarm goes missing wherever the chain between them is not linked.Why a Modbus Point Reads the Wrong Registerhttps://plantroomlabs.com/notes/modbus-register-addressing/2026-09-23T00:00:00Z2026-09-23T00:00:00ZModbus decimal addressing is zero-based, vendor documentation is not, and the Address Format property decides which of the two you are typing.Commissioning a JACE-8000 Without Locking Yourself Outhttps://plantroomlabs.com/notes/commissioning-a-jace-8000/2026-09-23T00:00:00Z2026-09-23T00:00:00ZThe factory address, the passphrase and the account you are made to delete — the commissioning steps that strand a new controller.BACnet MS/TP on a JACE: What to Sethttps://plantroomlabs.com/notes/bacnet-mstp-on-a-jace/2026-09-23T00:00:00Z2026-09-23T00:00:00ZBaud, MAC address, Max Master and Max Info Frames. Four settings on one Link component decide whether an RS-485 trunk works, crawls or drops the token.What Actually Blocks an AX to N4 Migrationhttps://plantroomlabs.com/notes/ax-to-n4-migration/2026-09-23T00:00:00Z2026-09-23T00:00:00ZA station cannot migrate until every module it uses has been refactored for Niagara 4 — and licences, users and permissions all change shape on the way.Pure Java or It Will Not Run: Inside a JACEhttps://plantroomlabs.com/notes/what-runs-on-a-jace/2026-09-22T00:00:00Z2026-09-22T00:00:00ZA controller is an ARM host with a fraction of a server's memory. Native libraries, JNI and heavyweight dependencies do not survive the move from a PC.Scheduled Niagara Backups, and the Supervisor Gaphttps://plantroomlabs.com/notes/scheduled-niagara-station-backups/2026-09-22T00:00:00Z2026-09-22T00:00:00ZA Supervisor can back up every station in its Niagara Network on a schedule. The station it does not cover that way is its own.Which Niagara Version to Stamp a Module Forhttps://plantroomlabs.com/notes/niagara-module-version-stamping/2026-09-22T00:00:00Z2026-09-22T00:00:00ZA module's declared dependency version is a floor, not a pin. Build against the newest SDK you have and stamp for the oldest station it has to load on.Niagara Module Signing: What a Station Checkshttps://plantroomlabs.com/notes/niagara-module-signing/2026-09-22T00:00:00Z2026-09-22T00:00:00ZNiagara's four verification-mode values, what each demands of your certificate, and the permissions that force a signature check even in low mode.Five Ways to Get Data Out of a Niagara Stationhttps://plantroomlabs.com/notes/getting-data-out-of-a-niagara-station/2026-09-22T00:00:00Z2026-09-22T00:00:00ZREST, MQTT, a relational history database, file export or an HTTP client. Which suits which consumer, and what each one costs you to run.Renaming Thousands of Niagara Points Safelyhttps://plantroomlabs.com/notes/bulk-point-renaming-and-tagging/2026-09-22T00:00:00Z2026-09-22T00:00:00ZPoint names arrive from the field device and there is no standard. What to use to select, rename and tag in bulk — and what a rename quietly breaks.