Stack Lights

What They Are

Stack lights are the colored signal lights (Green, Yellow, Red) mounted on or near the conveyor. They provide visual feedback to operators about the system status and validation results. A horn may also be included for audible alerts.

How They Work

Stack lights are controlled by the Arduino Portenta H7 or LattePanda Delta 3 controller. The GateKeeper application sends commands to the controller, which turns the lights on or off. The specific behavior depends on the stack light profile configured for each site.

Stack Light Profiles

Teasdale Profile

Used at: Teasdale Carrollton

State	Green	Yellow	Red	Horn	Description
Idle (validation OFF)	ON	ON	ON	--	All lights on = system standby
Validation ON (ready)	OFF	ON	OFF	--	Yellow only = ready for scanning
Pass	FLASH	OFF	OFF	--	Green flashes for configurable duration (default 5 seconds)
Fail	OFF	OFF	FLASH	YES	Red flashes + horn sounds
Warning/NOREAD	OFF	BLINK OFF	OFF	--	Yellow turns OFF briefly then back on
System Problem	OFF	OFF	FAST FLASH	--	Red fast flash (250ms) = hardware disconnection detected

CargillRfid Profile (Default)

Used at: Cargill St. Clair, Sidney, Gainesville, Fullerton

State	Green	Yellow	Red	Horn	Description
Idle (validation OFF)	OFF	OFF	OFF	--	All lights off = not validating
Validation ON (ready)	ON	OFF	OFF	--	Green on = system ready
Pass	BLINK OFF	OFF	OFF	--	Green turns OFF briefly then back on
Fail	ON	OFF	ON	--	Green + Red STAY ON until next scan
Warning/NOREAD	OFF	FLASH	OFF	--	Yellow flashes
System Problem	OFF	ON	OFF	--	Yellow stays on until problem resolved

Important: In this profile, fail is persistent. Green and Red both stay ON until the next case is scanned. This makes it very clear that the last case failed.

AV50 Profile

Used at: Hormel Austin, Beloit, Barron

State	Green	Yellow	Red	Horn	Description
Idle (validation OFF)	ON	ON	ON	--	All lights on = system standby
Validation ON (ready)	ON	OFF	OFF	--	Green on = system ready
Pass	BLINK OFF	OFF	OFF	--	Green turns OFF briefly then back on
Fail	OFF	FLASH	OFF	--	Yellow flash only (no red, no horn)
Warning/NOREAD	OFF	FLASH	OFF	--	Yellow flash
System Problem	OFF	ON	OFF	--	Yellow stays on until problem resolved

Note: The AV50 profile is intentionally subtle. Failures show yellow (not red) and there is no horn. This is because AV50 validates barcode presence only, and occasional NOREADs are expected.

Off Profile

Used when: Stack lights are not installed or should be disabled

All lights remain OFF in all states. No horn activity.

Profile by Site

Site	Profile	Horn Enabled
Teasdale Carrollton	Teasdale	Yes (on fail)
Cargill St. Clair	CargillRfid	No
Cargill Oil sites	CargillRfid	No
Hormel Austin	AV50	No
Hormel Beloit	AV50	No
Hormel Barron	AV50	No
Zebra Futures Lab	Off	No

Configurable Timing

Setting	Default	What It Controls
StackLightPassDurationMs	5000 (5 seconds)	How long the pass flash lasts
StackLightFailDurationMs	5000 (5 seconds)	How long the fail flash lasts
StackLightWarningDurationMs	500 (0.5 seconds)	How long the warning flash lasts
StackLightHornDurationMs	500 (0.5 seconds)	How long the horn sounds
SystemProblemFlashDurationMs	250 (0.25 seconds)	Speed of system problem flash (Teasdale)

Troubleshooting

Lights Not Responding At All

1. Check the controller connection in the diagnostics panel (Arduino or LattePanda).
2. Verify the controller shows "Connected."
3. Use the stack light test buttons in the diagnostics panel.
4. Check the StackLightProfile setting in appsettings.json -- make sure it is not Off.
5. Check log for [STACK-LIGHT] entries.

Wrong Light Behavior

1. Verify the correct profile is set for the site.
2. Confirm the profile name is spelled correctly (case-sensitive).
3. Check the startup log for: StackLightOrchestrator configured with profile: {Profile}
4. Restart the application after any configuration change.

Lights Occasionally Stuck

The system includes a reinforcement timer that re-sends the intended light state every 300-500ms. This corrects dropped serial or TCP commands. If lights stay incorrect for more than a second:

1. Check USB cable quality (for LattePanda serial connections).
2. Try a different USB port.
3. Check for repeated connection/disconnection messages in the log.

Horn Not Sounding

1. Check the StackLightHornOnFail setting -- it must be true.
2. Verify the horn is connected to the correct pin on the controller.
3. Check if the profile supports horn (only Teasdale enables horn by default).
4. Test the horn pin directly using the diagnostics panel.

When to Escalate

• Lights respond in diagnostics but not during validation (software issue)
• All lights stuck ON or OFF regardless of state
• Profile change has no effect after application restart
• Horn works in test but not during actual validation failures