Screen Sharing

A screen module shows a live picture of an OT screen, such as an HMI or an engineering workstation, in an IT-side web browser, through the diode. (DYODE v1 only.)

flowchart LR
    WS["OT workstation<br/>screenshot.ps1"] -->|"JPEG files"| FOLD["Input box<br/>'in' folder"]
    FOLD --> NEW["Newest JPEG,<br/>at most max_fps per second"]
    NEW -->|"DYO1-framed UDP"| D{{"Diode"}}
    D --> FRAME["Output box<br/>latest complete frame"]
    FRAME --> HTTP["HTTP server<br/>http_port 8080"]
    HTTP --> B1["/ : page with live view"]
    HTTP --> B2["/screen.mjpg : MJPEG stream"]
    HTTP --> B3["/screen.jpg : still image"]

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How it works

1. Something on the OT side writes JPEG screenshots into a folder that the input box can read. screenshot.ps1 is included for Windows.
2. The input module watches the folder and sends the newest image as one framed message, at most max_fps times per second (default 10). Older images that were superseded are simply skipped.
3. The output module keeps the latest complete frame. Each frame is CRC-checked, so a damaged frame is dropped and never shown.
4. Browse to http://<output-ip>:8080/ for a live view. /screen.jpg gives a single still, handy for dashboards.

There is no keyboard or mouse path. The picture is strictly view-only, because nothing can travel back through the diode.