# Wiring and cable diagram

Cable documentation is fiddly and error-prone by hand, and WireViz was built for exactly this: describe connectors, wires and connections in text, and get a correct harness drawing with a bill of materials.

Because it is generated, the diagram and the pinout cannot disagree.

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## When to reach for one

* Harness and loom documentation for hardware products.
* Field service documentation where the pinout is the instruction.
* Test rigs and lab setups that somebody else will have to rebuild.

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## How to draw it in Capable

| **Route** | **Use when**                                               |
| --------- | ---------------------------------------------------------- |
| WireViz   | Generated harness drawings with pinouts and a parts list.  |
| draw.io   | Simple point-to-point wiring where generation is overkill. |

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## A worked example

A three-wire harness with a real pinout:

![Wiring and cable diagram](https://help.gocapable.com/images/att1418461374.svg)

The source, which you can paste into a new diagram and edit:

```
connectors:
  X1:
    type: D-Sub
    subtype: female
    pinlabels: [DCD, RX, TX, GND]
  X2:
    type: Molex KK 254
    subtype: female
    pinlabels: [VCC, RX, TX, GND]

cables:
  W1:
    gauge: 24 AWG
    length: 0.3
    colors: [WH, BN, GN]

connections:
  -
    - X1: [2,3,4]
    - W1: [1,2,3]
    - X2: [2,3,4]
```

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## A few things that catch people out

* Wire colours in the diagram must match the wire colours in the box. Generate from one source.
* Include gauge and length; they are the two facts a person building it needs.
* Pin numbering direction matters. Say whether you are looking at the front or the rear of the connector.

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## Related

[Digital timing diagramWaveforms, clocks and bus transitions.](https://help.gocapable.com/diagrams/digital-timing-diagram.html)

[HDL block diagramComponent symbols generated from your HDL.](https://help.gocapable.com/diagrams/hdl-block-diagram.html)

[ExamplesWorking diagrams you can copy.](https://help.gocapable.com/diagrams/examples.html)

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_Approximately right is wrong here._