Thursday, September 6, 2012

Mastering the GigE interface

GigE is probably the de facto standard interface for machine vision. USB is fine for lab work but not really seen as industrial. CameraLink is the natural upgrade path when more speed is needed, and FireWire is just falling by the wayside. But if you’ve set up a GigE camera you’ve probably found it wasn’t exactly plug-and-play. That’s been my experience anyway.

The problem seems to be all the Ethernet-related terminology – ports, jumbo frames, IP addresses and so on - so I asked my best friend, (Google,) to help. Of course, Google throws up a gazillion links to ethernet primers, some of which are better than others. So in my self-appointed role as provider of useful machine vision information, here are my suggestions for learning more.

A good place to start is “How Ethernet Works” by Nick Pidgeon and posted on the howstuffworks website. It’s not detailed but in 10 minutes or less you can get a decent overview.

From there I’d go to “Ethernet Basics”, published by Nortel Networks. This is a 26 page pdf that goes in to CSAM/CD and MAC addressing. (Until I read this I never really grasped why smart cameras have a MAC address.)

Having taken that on-board, you should be ready to delve in to the OSI seven layer model, which is handled by the JDS Uniphase white paper, “Fundamentals of Ethernet”. (It’s another substantial pdf download.)

By now you should be ready for data packets and Ethernet devices, and here I have two suggestions. “Back to Basics: Data packets” on the Control Engineering website is a pretty easy read, and then there’s yet another pdf, “Fundamentals of Ethernet Technology” on the Krone website.

If you want to get a deeper understanding of the nitty-gritty – things like TCP, ports, IP addressing, subnet masks and so on – “Ethernet 101 – Basics of Ethernet Communication” is for you. Now this does get a little yawn-inducing because the narrator insists on reading his 48 slides, but at times he ad-libs to expand on important points, so stick with it; it’s good stuff.

Now I realize that this is a lot of reading and some of you might prefer to watch a movie. Inevitably, there’s a ton of Ethernet material on YouTube, although much of it I found rather poor. Some of the better stuff came from ProfessorNVCC and his series titled “Ethernet Basics Part 1”, followed of course by Part 2, Part 3 and so on.

And when you’ve digested all that, you’ll be an expert. Well not quite, but you will be ready to face the GigE Vision standard, downloadable from the AIA’s website.

Have fun!

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