A company operates multiple buildings equipped with digital signage displays. The screens normally show standard information such as company communications, meeting room schedules, dashboards, or visitor information. When a safety event occurs, a designated system communicates to all the players to display the corresponding alert above whatever content is currently running at that time.
Potential trigger sources include:
Building management systems
Fire detection and alarm systems
AMX/Crestron/Q-SYS control systems
This allows safety information to be displayed without modifying, republishing, or even knowing anything about the main content on the players.
Overview
The tutorial on this page shows how to create a player-level overlay that displays building safety alerts above any content running on a player. The overlay remains transparent during normal operation and becomes visible only when activated by an external system through a Shared Variable update. Because the project is configured as a player-level overlay, the alert appears above all other content displayed by the player, including ARYA alerts.
This approach allows alerts to be managed independently of the main content, making it suitable for deployments with many players and diverse content sources.
This tutorial demonstrates a digital signage integration and is not intended to replace certified life-safety, evacuation, or emergency-notification systems.
Architecture
Architecture diagram
A central building-management or control system monitors safety events; this could be a system from Crestron, AMX, Q-SYS, or an evacuation and alarm platform. When the control system detects or receives a building safety event, it updates a Shared Variable over the IP network to a predefined value, such as: NORMAL, ADVISORY, EVACUATE, ALL_CLEAR.
Every player is configured once with the URL of the same player-level overlay project, hosted centrally on a web server. The overlay continuously monitors the same Shared Variable and remains completely transparent while no alert is active. When the Shared Variable is updated, the overlay immediately reacts and displays the corresponding alert above whatever content is currently running on the player.
External systems only update the variable value; the overlay project is responsible for displaying the appropriate content.
Benefits of this approach
This architecture offers several advantages:
One centrally managed overlay project can serve many players.
The main signage projects remain unchanged.
Alerts can be updated immediately through Shared Variable updates.
The same overlay can work with content from ARYA, Elementi, or other sources.
The overlay can be maintained independently of the content shown on the displays.
The player-level overlay remains available regardless of the content-management system being used.
First, create the Elementi project that will be used as the player-level overlay. The project should contain several predefined alert layouts (e.g., ADVISORY, EVACUATE, ALL_CLEAR) and an Action to Switch widget to control which layout is displayed depending on the current state. The overlay must remain completely transparent while no alert is active (i.e., NORMAL state).
Design suggestion: use an amber banner (solid or nearly opaque background), occupying the upper or lower third of the screen, containing a short headline (e.g., “SAFETY NOTICE”), one concise instruction (e.g., “Please avoid the loading area until further notice.”), and optionally a warning note icon.
Design suggestion: use a full-screen red background, containing a large white headline text (e.g., “EVACUATE THE BUILDING), one primary instruction (e.g., “Use the nearest safe exit.”), followed by one or two supporting instructions (e.g., “Do not use the lifts. Follow instructions from authorised personnel.”), and optionally a warning icon.
Design suggestion: use a green, blue, or neutral background, occupying the upper or lower third of the screen, containing a short headline (e.g., “ALL CLEAR”), a brief instruction regarding return to normal activity. (e.g., “Normal operation may resume.”), and optionally a matching icon.
Click the “Fit Screen” button on the toolbar to make it full screen.
Configure the widget:
Double-click the widget's layer in the Edit panel to find its properties.
Enter the name of Shared Variable (e.g., “safety.alert”) to monitor for updates.
Disable the “Start with default page” option to retain recent updates upon opening/restart.
Building safety alert overlay - Action to SwitchGo to the “Mappings” tab, remove all the default entries, and define for each Shared Variable value (Action column) the appropriate content (Page column) to display: NORMAL → Empty text layer ADVISORY → Set the ADVISORY layout EVACUATE → Set the EVACUATE layout ALL_CLEAR → Set the ALL_CLEAR layout
Go to your overlay project and publish it on the web server. Follow the same steps for publishing to players, just select the newly created Publish Location as target.
Verify that the project's index file (e.g., https://server.example.com/overlay/index.svg) is accessible through HTTP. within the same network as the player(s).
For inspiration, you might want to check out these tutorials:
At the beginning, only the existing player content is visible, since the overlay remains transparent.
Next, update the Shared Variable as follows:
Update to
Expected result
ADVISORY
A safety advisory appears. The message is displayed above all content running on the player.
EVACUATE
The advisory is replaced by a full-screen evacuation alert. The main content continues running underneath.
ALL_CLEAR
The evacuation alert is replaced by an all-clear message.
NORMAL
The overlay returns to a transparent state and only the normal content is shown.
Optional extension
In larger deployments, location-based alerts may be required, while still using a single centrally managed overlay project. This could be achieved by having the Shared Variable carry additional information beyond the alert state, such as:
EVACUATE|BUILDING_B
or
EVACUATE|BUILDING_B|Evacuate Building B|Use the nearest safe exit. Do not use the lifts.
The overlay can then determine:
The alert type.
The target building or area.
Further details or instructions to display.
Some JavaScript code would be needed to parse the incoming value and to map players to buildings or areas.
Troubleshooting
Alert does not appear
Verify that:
The player-level overlay is configured correctly.
The overlay project is accessible from the player.
The Shared Variable name matches the configuration of the Action to Switch widget.
The Shared Variable value matches one of the configured actions.
Overlay remains visible
Verify that the Shared Variable has been reset to: NORMAL.
icon from the toolbar and disable the background property to ensure the overlay's transparency while no alert is active.
