Cables

How to choose machine vision cables

Most intermittent faults in a vision system - dropped frames, cameras that vanish from the network, triggers that go missing - trace back to a cable: wrong type for the motion, too long for the bit rate, or a connector that works loose. Choosing the cable takes four decisions: the interface, the connector at each end, the length and how the cable will move.

1. Match the interface and the connector at each end

Read the connector off the camera, code reader or frame grabber datasheet, not the photo. The data cables here cover every common camera interface:

A screw-locking connector matters on any machine that vibrates: a plain USB plug can unseat by a fraction of a millimetre and drop the link without looking loose. Angled connectors (up, down, left) save space behind a camera in a tight enclosure; check the direction against the camera's connector orientation before ordering.

2. Power and I/O cables

Industrial cameras take power, trigger inputs and strobe outputs through a separate connector, usually a 6-pin or 12-pin circular plug on area scan cameras, and M8 or M12 connectors with 8, 12 or 17 pins on smart cameras and code readers. The other end is usually open wires for terminal blocks, or a breakout with RJ45, DB9 serial and a terminal for I/O on code readers. Check the pin count and the coding (A-code for power and I/O on M12). If the camera is powered over Ethernet (PoE), the I/O cable is only needed for the trigger and outputs.

3. Length

Measure the real route through the cable chain and cabinet, not the straight-line distance, and add slack for the service loop. Stock lengths run from short 0.19-0.5 m jumpers to 60 m, with 3, 5, 10 and 15 m the most common. Do not coil a long cable to use up surplus length near a drive or servo cable; route it away from motor power. For bandwidth per interface, see the camera bandwidth calculator.

4. Static, drag chain or robot arm

This is the choice that decides how long the cable lasts. Static cables are for fixed installations. Drag-chain (high-flex) cables use finely stranded conductors and a jacket rated for millions of back-and-forth bends: where stated, 2 to 10 million U-type bending cycles. Robot-arm cables are also rated for twisting - 3 to 5 million cycles of ±180° torsion where stated. Respect the minimum bending radius, which runs from about 30 mm to 114 mm across this category; a high-flex cable bent tighter than that fails early. Our article on robot camera cable failures covers routing and strain relief.

What this category covers

• Camera data cables: GigE, 10 GigE (copper and multimode fibre, 850 nm), USB3, CoaXPress, Camera Link.
• Power and I/O cables for cameras, smart cameras and code readers: 6-pin and 12-pin circular, M8 8 / 12-pin, M12 8 / 12 / 17-pin.
• Frame grabber I/O cables for trigger and encoder signals.
• Power cords with country plugs and IEC C13 connectors for power supplies.
• Jackets: PVC for static use, TPU and nitrile PVC for drag chains and oily environments.
• Operating temperature: typically -20 °C to 75-80 °C; some connectors reach IP67 when mated with the camera.

Light extension and drag-chain cables for lights are listed under lighting accessories; brackets and spare parts for readers under code reader accessories.

Typical applications

• Cameras on linear axes and gantries, running through a drag chain.
• Eye-in-hand cameras on a robot wrist, where the cable twists as well as bends.
• Long runs from a camera on a large web or conveyor back to the cabinet PC over fibre.
• Line scan and high-speed cameras on CoaXPress or Camera Link to a frame grabber.
• Code readers wired to a PLC over a single M12 cable carrying power, I/O, serial and Ethernet.

Common mistakes

• Using a standard office patch cable or a static cable in a drag chain. It works on the bench and fails after weeks on the machine.
• Exceeding the length for the interface. A USB3 or CoaXPress link that is too long often runs, then drops frames under load.
• Mixing up the cable for a camera's I/O connector with one for a different pin count or coding - they may look alike.
• No strain relief at the camera: the connector, not the cable, takes the load and breaks.
• Running camera cables in the same duct as servo motor cables.

Questions

Can I use a normal Ethernet cable for a GigE camera?
On the bench, yes. On a machine use an industrial cable with screw-locked RJ45 at the camera, shielding, and a high-flex rating if it moves.

How long can a USB3 camera cable be?
Passive cables are reliable for a few metres. For longer runs switch to a GigE camera or use an active or fibre extension.

When do I need fibre?
For 10 GigE runs beyond what copper carries, through electrically noisy areas, or between buildings. Multimode fibre at 850 nm with LC connectors is the common choice.

Which cables does my system need?
Configure the system: the camera choice sets the data and I/O connectors the cables need.