Typical FireWire cable with an aluminized polyester shield after 100,000 cycles of rolling flex on a 50 mm bend radius. Insulation and conductor damage appear where shields have cracked.

Paul Warren
Product Development Engineer
W.L. Gore & Associates Inc.
Elkton, Md.

Ethernet, Gigabit Ethernet, FireWire, Camera Link, and USB protocol are the back-bone of today's digital video and motion control systems. To work properly, these networks require cabling in which signals travel on controlled impedance, differential pair conductors. Why? Digital signals common to machine vision and motion control are sensitive to impedance changes in the cable itself. This raises the bar beyond the typical cable made with aluminized polyester shields. Often, the life of the shields determines the functional life of the entire motion system.

The main problem with conventional cable is that it's not made to carry data in a high-flex environment. When such cable is used in vision-based motion systems, communication failures between the camera and system begin to show up before any mechanical wear of the cable can be observed. One solution is to use controlled impedance cables, which not only survive the rigors of millions of flex motions (from a mechanical wear-out standpoint), but also ensure reliable data links for even the fastest signal protocols on the market.

The difference between cable types is most apparent when they are tested head to head, using rigorous test methods that bring controlled-impedance cable to failure in robotic flexing applications. The results from these tests show what kinds of cables canmeet the electrical requirements needed to handle the repeated flexing ofautomated motion-centric processes.