Help:Diagrams

This wiki can store diagrams as diagrams rather than as uploaded pictures. A diagram lives on its own page, keeps a full edit history like any other page, and can be re-opened and changed by the next person — no hunting for the original file, and no re-uploading a flat image every time something moves.

You need to be logged in and in the writer group to create or change a diagram. Anyone can view them.

The five formats

Each format has its own namespace, and each has its own editor.

Namespace	Best for	How you edit it
Mermaid:	Flowcharts, sequence diagrams, state machines, ER diagrams, timelines	Text — you write a few lines of Mermaid syntax
DOT:	Graphs and trees: signal chains, network maps, workflows	Text — Graphviz DOT syntax
Drawio:	Free-form drawings, block diagrams, anything you want to drag around	Full visual editor (draw.io / diagrams.net)
BPMN:	Formal business-process diagrams	Visual editor
Gantt:	Project schedules with dependencies	Visual editor

Mermaid and DOT are the two most useful here for typical hardware, RF and reverse-engineering documentation, and they are the easiest to review in a diff because the source is plain text.

Creating a diagram

The easiest way is to write a red link and click it:

On any page, add a link in a diagram namespace, for example [[Mermaid:Meter capture chain]].
Save, then click the new red link.
The diagram editor opens directly. Fill it in and save.

You can also go straight to the editor for a page that does not exist yet by visiting its URL with ?action=editdiagram on the end.

On a diagram page that already exists, use the Edit diagram tab at the top.

Showing a diagram on another page

Diagram pages are not transcluded with the usual double braces. Use the #display_diagram parser function instead:

{{#display_diagram:Mermaid:Meter capture chain}}

That renders the diagram inline wherever you put it, so an article can show a diagram that is maintained on its own page.

Mermaid example

The source of Mermaid:Example diagram is simply:

flowchart LR
    A[Smart meter] -->|900 MHz| B(SDR capture)
    B --> C{Decodes?}
    C -->|yes| D[rtlamr output]
    C -->|no| E[Adjust gain / freq]
    E --> B

which renders as:

flowchart LR A[Smart meter] -->|900 MHz| B(SDR capture) B --> C{Decodes?} C -->|yes| D[data output] C -->|no| E[Adjust gain / freq] E --> B

Mermaid supports far more than flowcharts — sequence diagrams, state diagrams, class diagrams, ER diagrams, pie charts, timelines and Gantt charts are all available. See the Mermaid documentation for the full syntax. Note that this wiki bundles Mermaid 10.9, so diagram types added in Mermaid 11 will not render.

DOT example

DOT:Example diagram contains:

digraph FlashExtraction {
    rankdir=LR;
    node [shape=box];
    "Target PCB" -> "Desolder chip";
    "Desolder chip" -> "Socket adapter";
    "Socket adapter" -> "Programmer";
    "Programmer" -> "Binary dump";
    "Binary dump" -> "Analysis";
}

giving:

digraph FlashExtraction { rankdir=LR; node [shape=box]; "Target PCB" -> "Desolder chip"; "Desolder chip" -> "Socket adapter"; "Socket adapter" -> "Programmer"; "Programmer" -> "Binary dump"; "Binary dump" -> "Analysis"; }

DOT is good when you want the layout worked out for you — you describe what connects to what, and Graphviz arranges it.

A note on Drawio

The Drawio: editor is the full diagrams.net drawing tool, loaded from the external site embed.diagrams.net while you are editing. Your diagram is saved here on the wiki, not on their servers, and viewing a saved Drawio diagram does not contact them at all — but editing one does need that external site to be reachable from your browser. The other four formats are served entirely from this wiki.

Tips

Diagrams are ordinary pages: History, Talk, watchlisting and the normal backups all apply.
Because Mermaid and DOT are text, their page histories produce readable diffs — prefer them over an uploaded image when the diagram is likely to change.
In a BPMN diagram, an element named [[Some page]] becomes a link to that wiki page.
Give diagrams descriptive names, the same as files — Mermaid:Landis Gyr Focus teardown steps beats Mermaid:Diagram 3.