Lynn's Industrial Protocols over IP

Thursday, February 01, 2007

Do Users Really Want Industrial Ethernet?

(For those impatent to read this to the end - I'm not saying don't use Ethernet ... I am just saying be careful you understand what your customers expect and what functionality they will assume you include *for free* when you add Ethernet)

My last post created some interesting feedback. But I want to emphasize a topic from that post more fully. For the last 15 years I've been involved in the "multi-vendor interface" business - linking multiple vendors' equipment by data comms. First I worked in RS-232 and 485, then fiber optics, then Ethernet, and now by virtually every technology that moves TCP/IP.

From time to time I am contacted by some pretty desperate customers - for example I had one customer who had piloted some Ethernet-based temperature sensors. Things worked fine in the lab with their lab computer, so they bought 50 ... only to find out they couldn't use them. It seems these sensors really were "just Ethernet" - they talked by Ethernet broadcast and direct MAC-layer packets. They didn't support TCP/IP and therefore could NOT be routed by any standard network infrastructure. The user could not talk to any of the sensors they had intended to install in panels around the plant because the "Computer Room" wasn't on the same physical Ethernet segment as the "floor". There was no way to broadcast or unicast MAC-level between the systems. This customer hoped I knew of some magic box to act as gateway between TCP/IP nodes and pure Ethernet nodes; I didn't.

So this brings me back to the concept of the true cost to implement "Ethernet". Customers who ask for Ethernet are not really asking for Ethernet hardware or an Ethernet media bus. They have the expectation that they can interface your "Ethernet Devices" with the wide variety of other equipment they have - including WiFi, routed Ethernet, fiber optics, wide-area networks, and so on. They also expect (at least in a future firmware rev) web pages for configuration, SNMP for remote management, strong encryption, and so on.

So the term "Ethernet" has taken on a life of its own - remember when 802.11 was called "Wireless Ethernet". Well, there is absolutely NOTHING Ethernet about 802.11, yet it was a useful PR move to link the two. No doubt it helped spread the acceptance of WiFi as we now call it. Interestingly enough, the current PCI verse PCI-Express adapters you buy for a PC are using the same PR trick - linking a new, unknown technology to an old established technology that merely accomplish the same function by very different means. Maybe Sony should have called Beta-Max VHS-Max instead ... but then I'm showing my age by even knowing that a consumer-oriented video standard other than VHS even existed.

But back to Ethernet. If you are a small device maker and have yet to start making Ethernet-based products, just be aware that customers who ask for "Ethernet products" aren't really asking for ... err, products with Ethernet. They are asking for products which integrate into (at a minimum) the wide family of TCP/IP based technologies out there. I am not even talking about should you support Modbus/TCP or ODVA Ethernet/IP or ProfiNet yet. I am just saying customers will expect your "Ethernet products" to be able to hold a raw TCP/IP or UDP/IP conversation with all of the other equipment they are investing in daily.

So the cost to add an Ethernet port is just a small part of your cost to "add Ethernet". That is why companies like Digi can sell Ethernet-to-Serial converters or sell "async Ethernet driver chips" like the Digi Connect ME which links to your CPU's serial UART. These devices of course cost more than $9.95 or even the cost of a few new hardware chips, but that higher cost is paying for TCP/IP, web servers, SNMP servers, strong AES encryption and all of the other things your customers expect when the buy "Ethernet products".

So to digress a bit, I suffer this "Oh, don't worry ... it's Ethernet" on a daily basis. So far I have to say at least 95% of the off-the-shelf software applications I test supporting TCP/IP don't work well with technologies other than direct Ethernet. This includes problems not only when extremely different media like satellite or cellular, but even when WiFi is used. So that is part of my mission in this blog - what you want is NOT to Ethernet-enable your products. Instead you need to "IP-enable" your products by way of an Ethernet interface.

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