Monday, July 16, 2012

Shielded Waterproof USB Cables, Bulkheads, and Covers

Waterproof USB: Shielded vs. Unshielded

( Shielded Waterproof USB 2.0 Cable with Type A Female to Type A Male

A lot of people already know about L-com's large selection of waterproof and IP67 rated USB cables, panel-mount adapters, and connector covers. But do you know about the various shielding options available? In order to ensure the high-speed connection that USB technology offers, it is important to ground the shield in the cable, and that goes the same for the waterproof cables.

USB Weatherproof Products

Shielded Waterproof Cap for USB IP67 Cables

But let's take a step back and look at the different kinds of products for USB that are IP67 rated (or functionally waterproof). The most basic options are USB cables, which usually have a waterproof connector at one end (with either a "hood" around the male connector or threads around a female connector for a hood to screw on to and panel mount). Options include waterproof USB Type A female bulkhead to regular Type A male, which is the most common, but there are also waterproof USB Type B male to regular Type B male, waterproof USB Type A male to regular Type B male , and waterproof USB Type B female bulkhead to regular Type A male. There's even a mini B 5 position version!

For adapters, the most common are the waterproof Type A jack to flying leads, and the waterproof Type B jack to flying leads. The 10" long lead wires can be soldered to a PCB or even terminated in other, non-standard connectors. This allows you to build a waterproof box or chassis with the USB female jack available to mate to. For tricky, field installations, L-com also has field install USB Type A and Type B connectors that are handy to have in an emergency.

Finally, there are a variety of waterproof covers to put over the female jacks when not in use. L-com carries an unshielded version with a chain lanyard and one with a rubber lanyard. In either case, the cover can be tied up close to the mounted jack so it is easy (and hopefully, unforgettable) to cover the port when you disconnect from it. There's also replacement gaskets and nuts to help with panel mounting.

Why shield USB?

USB 2.0 Cable Construction Showing the Braid and Foil Shield

The USB standard has a double-shield in the cables, one a braid shield, the other a foil shield. Whenever you have shielded cable, that shield needs to drain or else the electromagnetic interference will build up and erode the signal quality. Sometimes, the USB link is drained at the source, but not always. For those cases, and if you aren't sure, it is best to use a shielded waterproof cable (like L-com's Type A female to Type A male, or Type A male to Type B male) and a shielded USB cover. That way the accumulated EMI can drain either (or both) at the source or at the panel.

Quick note: L-com has everything from common USB cables to complex panel mount adapter solutions available. Browse their USB product center for a range of products, but also check out USB panel mount lightning protectors and even USB KVM switches and extenders.

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