Design Wire Harnesses

Get a cable design that matches your boards, without a second pinout in a spreadsheet. Flux is an AI hardware engineer. Flux designs each cable from the connectors and nets in your project and documents it in the project files.

Describe the harness

Tell Flux what the cables connect, which connectors they use, and how long they are.

I am building a small ground robot. Design the wire harness that connects the main controller board to the drive motor driver and the battery. Use JST GH connectors on the controller side and XT30 for battery power. Each run is 250 mm.
Design the harness between the flight controller and the four ESCs of this drone. Each signal cable is 150 mm.
Design a 600 mm harness from the vehicle control unit connector J1 to the dashboard connector J2. Match pins that share a net.

Open the Chat panel and describe the cables. When Flux needs more data, it asks you in the chat. For example, it asks for the pinout of a board that is not in the project, or for the battery voltage and current. Reply in the chat, or tell Flux to define the values that you do not have. Flux states each value that it chose.

Choose connectors and mating housings

Tell Flux the board connectors at each end of the cable. Give the reference designators in the project or the connector part numbers.

Use J1 and J2 in this project as the two ends of the cable.
The controller uses a JST B4B-PH-K-S header. Find the mating housing and the crimp contacts for the cable.

Flux finds the mating cable housing for each board connector. It uses the housing that the board connector's datasheet names as its mate, not the board-mounted header. Flux also lists the crimp contacts, and the contact gender at each end.

Choose wires

Tell Flux the gauge, wire family, or colors when you want specific values. Tell Flux the current when a wire carries power.

Use red for 5V, black for GND, and one color for each signal wire.
The battery is a 3S LiPo, 11.1 V, 15 A continuous and 30 A peak. Size the power wires for that current.
Use 22 AWG wire for all wires in the test rig cable.

Flux makes one wire for each net that both ends share. When you do not give the wire values, Flux selects stocked UL 1007 wire, the thinnest gauge that both connectors accept, and one color for each wire. When a net carries more current than that gauge can carry, Flux selects a thicker stocked gauge.

Set the cable length

Tell Flux the length of each cable.

Make the signal cable 250 mm and the power cable 300 mm.
Each drone arm cable runs 180 mm from the flight controller to the arm board.

The length depends on where the parts are in the device and how the cable runs between them. When the request has no length, Flux asks for it before it quotes. The wiring table records the length of each wire.

Get the wiring table and the harness drawing

Tell Flux which documents you want for the harness.

Give me the connectors and mating housings, the wire gauge and color for each wire, the pin-to-pin wiring table, and a harness drawing.
Add a cable bill of materials for 10 sets of the harness to the project files.

Flux writes a harness build record to the project files. Select Files in the project view switcher to open it. The record contains:

  • A harness drawing that shows each cable from end to end, with the connector, pin, signal, color, gauge, and length of each wire.

  • A pin-to-pin wiring table for all wires.

  • A cable bill of materials with the housings, contacts, connectors, wire, and labels, for one set and for the quantity that you ask for.

  • Assembly and test steps for the cable.

  • The quote from the manufacturer, when you ask for one.

This example shows a part of the harness drawing for the logic cable of a ground robot:

CABLE A — LOGIC: C1 controller C2 driver
JST GHR-06V-S + female contacts JST GHR-06V-S + female contacts
1 5V ---- red 26 AWG, 250 +/-5 mm ---- 1 5V
2 GND ---- black 26 AWG, 250 +/-5 mm ---- 2 GND
3 PWM_A ---- blue 28 AWG, 250 +/-5 mm ---- 3 PWM_A
4 DIR_A ---- white 28 AWG, 250 +/-5 mm ---- 4 DIR_A
5 PWM_B ---- green 28 AWG, 250 +/-5 mm ---- 5 PWM_B
6 DIR_B ---- yellow 28 AWG, 250 +/-5 mm ---- 6 DIR_B

Change the harness

Tell Flux what to change.

Swap the DIR_A and DIR_B wires and update the drawing and the wiring table.
Change the power cable to 400 mm and quote the set again.

Enter the change in the same chat thread. Flux updates the harness build record and makes a new quote when you ask for one.

Next steps


Next to read:
Wire Harness Quotes and Orders
On This Page
Design Wire HarnessesDescribe the harnessChoose connectors and mating housingsChoose wiresSet the cable lengthGet the wiring table and the harness drawingChange the harnessNext steps