Thursday, December 24, 2015

USB Superspeed and Machine Visions/Industrial Cameras

In our market, we have many customers who are having problems with cables that they've purchased elsewhere.  They have data integrity problems (ie, the cameras aren't as fast as they should be due to dropped frames), or during device testing they have ESD or EMI problems.

After so many years in this industry, we have come to learn a lot about the intricacies of building a proper USB cable - one that is not just to spec, but one that is properly made for a specific industrial application, like machine vision, which can require tighter specs than what the USB spec requires - especially if you need to go outside of the spec, such as needing an extension cable (which is not permissible in the spec) or if you have a high static environment and you need to drain the ESD (no fixes listed in the spec), nor using angled connectors (only a couple are even listed in the spec, and those are solely for USB 2).

Because there are so many things that we could discuss, I would like to welcome you to contact me directly for a specific question.  When I find some that are noteworthy enough, I'll publish the details here for the common benefit and the advancement of proper techniques within our industry.

To be frank, for an advanced level of usage of USB 3.0 / USB 3.1, the scope that we need to operate at is very high; unfortunately, many cables that we've tested, even cables that have been certified, are so loose within the spec (although they do appear to be within spec) that they cannot fit into an MV application.  They cause strange errors and differ from cable to cable.  It's unfortunate, but the reality.

So, as I get your questions, I'll publish more.  Contact me at our website,

Wednesday, October 14, 2015

USB Splitter Cables

USB Splitter Cables

There is a lot of misinformation out there about USB hubs and USB splitters in general.  I am going to try to help clear up the confusion.

Here are the two main questions I get
1.) How to hook up 2 computers to 1 printer with USB (as stated as the original question here).
As the previous poster said - you need a switchbox, not a hub (or also commonly referred to as a splitter).  There are 2 types of switches that you can use
   a.) Manual switch - with this, you have to manually switch the box in order to print from each computer.  It's cumbersome, but available.  Your computer will have to re-recognize the printer each time.  It's cheap, but available.  Just search for "USB manual switchbox" and you'll find tons of them for sale - they start at about $15/ea - shipped
   b.) Auto switch - a switch like this is highly recommended.  These switches will auto-sense a print job, switch it over to the computer that is printing.  I've used these several times and they generally work well.  The cheaper ones can be a little flaky - not sensing correctly and having to reset it, but the really expensive ones are really only necessary if you're doing this in a commercial/industrial setting; where it needs to work flawlessly.  There are differences between them, for sure.  For this item, simply search for "USB autoswitch" and you'll pull up a lot of results.  These start at around $18/shipped.

2.) The second question that I get is "do you have a USB splitter"... they don't want a hub, just a splitter.
First of all, in order to split USB, you have to use a hub.  It's a digital signal, which means that there is electronic data that is routed.. It's not like an analog system, like audio, or VGA, where a signal can flow to multiple devices.  For that, you need to use some type of hub.  The confusion is the references that are made.  A true USB splitter will split a single USB connection on a computer into multiple connections so that you can plug in multiple devices, like a keyboard and mouse, into a single port on your computer.  There are many out there, from Wal-mart to Best Buy, to Joe's Computer Shop down the street.
Here's a link to one that is offered at USBFireWire - it's a little higher end product (commercial quality).  It's only for this use - this won't work as a usb switchbox, and it won't work in the reverse (ie, in the above application).  It's solely meant for 2 devices, like a keyboard and mouse, into one port.

I hope this post is detailed and helpful.

**UPDATE and WARNING** I have also found a second type of USB splitter on the market.  It appears to be the same the original one designed by, but is instead wired direct.. however, only partially.  They claim that it can charge two devices, but only transfer data to one.  I thought, what the heck are they trying to do?  I found out that they have no 'hub' chip in the splitter, it's a simple straight wiring.  This can cause huge problems!  If your device negotiates a certain amount of power flow from one device, then output that to two devices, you could either be in for a slow charge (not a problem, just slow charging), but in a worst case scenario, your device could negotiate a higher charge rate (think fast-charge) and could overload your other device and blow your device if it were to receive more power than it can accept, or the cable you have plugged into the extension could burn the wiring if it's not made to carry that much power.  So, know what you're purchasing!