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Reader Start/Stop Operations

How to start and stop R700 readers via Titan hub UI.

Overview​

Start: Begin RFID reading (radio on, tags detected)
Stop: Cease reading (radio off, no tag reads)

With CAP installed: Hub UI buttons work (commands sent via MQTT)
Without CAP: Must start/stop via reader's own web UI (stock firmware cannot subscribe to MQTT commands)

Starting a Reader​

Via Hub UI (Requires CAP)​

  1. Log into hub.titanrfid.com
  2. Navigate to Readers
  3. Find reader → click Start button
  4. Wait ~2 seconds for ack

Behind the scenes:

  1. Hub publishes {"kind":"start","id":"uuid","preset":"titan-default"} to titan/v1/{serial}/commands (MQTT, retained, QoS 1)
  2. CAP receives command → POSTs to reader REST API: /api/v1/profiles/inventory/presets/titan-default/start
  3. Reader starts reading
  4. CAP publishes ack: {"id":"uuid","ok":true,"status":"started"} on command-response topic
  5. Hub shows reader status: Online, Reading

Latency: ~2 seconds (MQTT + REST API + ack)

Via Reader Web UI (Always Works)​

If CAP not installed, or hub buttons don't work:

  1. Open https://<reader-ip>/
  2. Navigate to Profiles → Inventory
  3. Select preset (e.g. titan-default)
  4. Click Start

Note: Reader will publish tag reads to Titan (stock firmware handles MQTT publish), but hub Stop button won't work.

Stopping a Reader​

Via Hub UI (Requires CAP)​

  1. Hub → Readers → [Reader] → Stop
  2. Wait ~2 seconds for ack

Behind the scenes:

  1. Hub publishes {"kind":"stop","id":"uuid"} to titan/v1/{serial}/commands
  2. CAP → POST /api/v1/profiles/stop
  3. Reader stops reading
  4. CAP acks on command-response
  5. Hub shows reader: Online, Idle

Via Reader Web UI (Always Works)​

  1. https://<reader-ip>/ → Profiles → Inventory
  2. Click Stop

Reader States​

Hub UI StatusMeaningRadioTag Reads
Online, ReadingStarted, tags being detectedOnArriving
Online, IdleStopped, no readingOffNone
DegradedTag reads arriving, but no command acksOnArriving
OfflineNo telemetry (reader powered off or network issue)UnknownNone

Degraded: Usually means CAP not installed, or CAP offline. Tag reads work (stock firmware), but Start/Stop buttons timeout.

Presets​

Readers start with a preset (configuration: RF power, session, filter, antennas).

Default preset: titan-default

  • All antennas enabled
  • Max power (31.5 dBm)
  • Session 2
  • Filter: all tags

Custom presets: Can be created in hub UI or pushed via API. Future feature: push custom preset via hub → reader.

Automatic Restart After Reboot​

If preset is named (e.g. titan-default):

  • Reader restarts preset after reboot (saved to disk)
  • Power cut → reader comes back reading

If preset is transient (started via POST /profiles/inventory/start without name):

  • Reboot leaves reader idle
  • Power cut leaves reader idle until manually restarted

Titan always uses named presets. Readers recover from power cuts automatically.

Troubleshooting​

Start Button Does Nothing​

Symptom: Click Start, nothing happens (no ack, no error)

Check:

  1. CAP installed? (Reader web UI → Apps → Titan Agent)
  2. CAP running? (Status = Running)
  3. CAP log: Subscribed to commands? (Subscribed to titan/v1/{serial}/commands)
  4. Hub audit log: Command published? (Audit → Recent activity)

Fix:

  • Install CAP if missing (see CAP Install)
  • Restart CAP if crashed (Apps → Restart)
  • Check identity files if not connecting (/cust/rw_dir/ missing files)

Start Works, But No Tags Appear​

Symptom: Hub shows "Reading", but Tag Data empty

Check:

  1. Reader really started? (Reader web UI → Status → Inventory profile active)
  2. Tags present? (Wave tag in front of antenna)
  3. Antennas enabled? (Reader web UI → Antennas)
  4. Antennas mapped to zones? (Hub → Zones → Map antennas)
  5. MQTT telemetry flowing? (Hub → Readers → Last Seen timestamp updating)

Fix:

  • Check reader's own tag read count (web UI → Status → Tags read)
  • Check MQTT config (broker address correct?)
  • Check firewall (reader → broker traffic allowed?)

Stop Button Times Out​

Symptom: Click Stop, spinner forever, eventually timeout

Check:

  1. CAP running?
  2. Reader reachable over MQTT?
  3. CAP log: Command received?

Fix:

  • Restart CAP
  • Manually stop via reader web UI (workaround)

Reader Starts, Then Stops On Its Own​

Symptom: Reader starts reading, then stops minutes/hours later

Check:

  1. License valid? (Expired license may stop readers)
  2. Reader preset saved? (Named presets survive reboot; transient don't)
  3. CAP crash-looping? (Apps → Log → repeated restarts)
  4. Reader firmware issue? (Impinj firmware 10.0.0+ required)

Fix:

  • Check hub license status (Settings → Subscription)
  • Verify preset name (not transient start)
  • Check CAP log for errors

Start Fails With Error​

Hub shows: "Failed to start reader: <error>"

Common errors:

  • "Preset not found": titan-default preset missing on reader
  • "Reader offline": CAP not connected, or reader powered off
  • "Permission denied": Reader REST credentials wrong (titan.json)
  • "Preset already started": Reader already reading (idempotent; not really an error)

Fix:

  • Create titan-default preset on reader (or use different preset name)
  • Check CAP connection
  • Re-provision identity if credentials wrong

Command History​

View past Start/Stop commands:

  1. Hub → Audit Log
  2. Filter by Resource: Readers, Action: start or stop
  3. See: timestamp, user, reader, outcome (acked / timeout / error)

Per-reader:

  • Hub → Readers → [Reader] → History
  • Shows commands issued to this reader

Performance Notes​

Command latency: ~2 seconds (hub → broker → CAP → reader REST API → ack → hub)

Concurrent commands: CAP processes one command at a time. Multiple Start commands queued → processed in order.

Retained commands: Commands are retained on broker. If reader reboots, last command is re-delivered. (Idempotent: start when already started = no-op)

Timeout: Hub waits 30 seconds for ack. If no response, command marked "timeout" (but may have succeeded - check reader directly).

Without CAP: Manual Operation​

Stock firmware (no CAP):

  • Tag reads published to Titan (MQTT publish works)
  • Hub Start/Stop buttons timeout (stock firmware cannot subscribe)
  • Workaround: Start/stop via reader's own web UI

When to operate without CAP:

  • Lab/dev environment (manual control acceptable)
  • Reader firmware too old for CAP (older than 10.0.0)
  • CAP install not yet completed

Production: CAP strongly recommended for remote Start/Stop.

Next Steps​