I had one of those calls the other day. I’d actually love getting these out of the blue calls. You never know who they are, where they are or what they might say.

Most of the time these people are pretty capable and smart, sometimes they’re whack jobs.

One time a guy asked me if I could go to Malaysia. Well, I like to travel and don’t really know for sure where Malaysia is, so I said sure, I’ll go. If he thought I could help, who am I to deny him?

Then he tells me that I have to fly in on a helicopter. Oh – Oh. I am just terrified of helicopters. I have this perception that in a jet, we can just glide to a landing but in a helicopter I’m just gonna drop out of the sky. It turns out that I once, a long time ago, knew a dancer (ok, a stripper) that was a helicopter pilot. She assured me that they can “freewheel” or whatever the term is without an operating engine and land safely. In fact she practices that every week. I didn’t believe a lot of what she told me and I really didn’t want to experience a helicopter ride in which the pilot is going to turn the Engine off.

So the next thing out of his mouth is that the reason for the helicopter is that it’s too dangerous to go in on the ground. So, now I’m thinking that if I survive the crash, they’ll be a bunch of people who want to torture/eat/kill me. My rule of foreign business trips is to try to come back alive – you can’t tell a great story at a cocktail party if you’re dead. So, in the end I passed on the trip.

Anyway, the guy the called the other day asked me to tell him what the input and outputs were. “What inputs and what outputs?”, I said. He says he wants to implement his own embedded EtherNet/IP device and needs to know what the message in is and what the message out is.

After a few minutes of this it finally occurs to me that this guy thinks that EtherNet/IP is just some sort of Modbus messaging system. There’s a Master. The Master sends a message. The device responds to it. It’s no big deal.

Well I start to tell him about CIP object Models, Forward Opens, IGMP Multicasting, IO Messaging and all the rest but he doesn’t want to hear it. He just wants to know what  the GUZZINTOS and GUZZOUTTOS are. I tried to tell him that’s it a 6 or 8 inch specification of how all this works. That it took us almost 2 years to get it implemented and that we went through 2 years of field trials before we did this.

He was kind of shocked by that. But in the end, I really think he didn’t believe me. So I told him he could get the free version at the ODVA site. It’s not really up to date, there’s no one to tell you how to customize it for your device, how to build an object model with it or support you at the ODVA lab or when your product doesn’t work at a customer site.

Finally, he terminated the conversation. Probably to throw darts at my picture (which you can get at www.rtaautomation.com). Some folks just want to believe that life is simpler than it really is.

Had a call from a really nice guy down south today who wants to implement EtherNet/IP. He seems to be really, really competent and sincerely wants to architect the right solution for his application.

The only problem is that this application isn’t appropriate for EtherNet/IP. This is a situation where it just doesn’t fit. He and his group are kind of enamored with the technology and the “thrill” of using a name technology.

It’s a classic illness that all us engineers are prone to get. We let are enthusiasm for some cool technology get way ahead of the problem we’re trying to solve. I did it with DeviceNet. Long time ago I created this really cool ISA bus coprocessor that was a DeviceNet Master. I got so excited by the technical challenge that I forgot completely about the business issues. The product was a big flop.

This guys problem is that he really has an Ethernet Peer-Peer system. He has a number of distributed application components and he wants to add and remove them at will without any reconfiguration.

His application reminds me of J1939. That’s a CAN based application layer protocol just like DeviceNet. Only J1939 is all broadcast. Each node publishes its data as needed to the network and who ever needs that data listens for it. There are no masters or slaves. If a node isn’t there the data isn’t published and the listener doesn’t receive it. It’s really simple and straight forward, used in transportation applications. I implemented a system for huge yachts one time. Catepillar engines use it extensively.

So this guy wants to do the same thing on Ethernet. One choice is to use CAN and J1939 but the physical distribution of the system prohibits that solution. CAN is good to 1000 feet unless you use extenders.

He could use Profinet CBA. But the size and complexity of that mother is just prohibitive. His data is pretty simple. Not sure that CBA makes a lot of sense in his application.

Another is proprietary. He could implement a J1939 like proprietary Ethernet application layer but is that the best solution?

One of the things he is looking at is Microsoft Robotics Studio. That a system targeted to students that makes it easy to program robots. It supports a bunch of different hardware platforms including PCs which is what our southern friend is using. It has simulation and tools for accessing sensors and actuators. It is designed for distributed systems where the robots can coordinate their actions. Here’s where you can get more information: http://msdn.microsoft.com/en-us/robotics/default.aspx.

I’ll have to admit that I didn’t have a good solution for him. Any thoughts from my “legion” of loyal readers? J

I’m at the EtherNet/IP ODVA meeting in Charlotte today. One of the biggest questions at the meeting is the definition of jitter. Many people are very unclear on the meaning of Jitter. In very simple terms, network jitter is simply the deviation between the time when a device is expected to issue a message and when the message is actually transmitted. For example, if a DeviceNet or EtherNet/IP device is expected to issue cyclic messages every 10msecs (very typical cycle time) and sends them between 9 and 11 msecs then we have 1 msec of network jitter.

So what’s good? Well, anything less than 50% jitter is acceptable. So, in our previous example, a device could send the next cyclic message between 5 and 15msecs of sending the last one. Unless you have a very high speed, timing critical application network jitter like this is acceptable. Once the device gets over 50% jitter though, the Client or Master device might begin to detect missing messages. If the jitter gets bad enough, the Master (Client) might even shut the device down and try reconnecting to it causing a loss of data or worse.

A good question that came up at today’s meeting was about Ethernet switches. What is the impact of the switch on network jitter in an EtherNet/IP network. Well, it turns out that it is nearly nothing. As switches receive a packet they analyze the first few bytes of the packet to identify the outgoing port and immediately start to send message out that port, even before the end of the message is received. At this speed the switch adds almost nothing to network jitter.

What’s the COCO object you might ask? Well, for the past 8 years the only way to configure an EtherNet/IP Scanner was to use some proprietary way of entering the list of devices to scan. In ControlLogix you used RsLogix. You added devices to the EtherNet/IP device table one by one. Unless, of course, the devices were RA devices or special partner devices and the data was already all known to RsLogix.

Well now, there is an Object that is defined that allows configuration of the EtherNet/IP Scan Table over the network. Now, standard EtherNet/IP tools can be used that can read and write the COCO (Connection Configuration Object, Object Number F3 Hex) using EtherNet/IP Explicit messaging. It may not seem like a big deal but this really matters and it going to be great for all the non RA Scanner guys. 

The next enhancement which some smart guys are already working on is an EDS connection. A tool should be able to read an EDS, let the user connect to the device, configure it and then load the appropriate information on the device into the COCO object of the scanner that will be using that device. That kind of tool is going to save users lots of work.  

The COCO document from the ODVA defines all the instances, attributes and behaviors of this new object. I’ll send it to you if you’re interested.

John

PS: If you’re interested in EtherNet/IP, you should take a look at our Instant EtherNet/IP IC solution. It is the absolute, hands down best way to get a server device EtherNet/IP enabled. Here’s the Instant EtherNet/IP solution.

There are a couple of idiosyncrasies of the human mind that never fail to amaze me, especially in myself. One of the big ones is how we all perceive that everything we know is common knowledge to everyone else on the planet. Actually, we all have specialized knowledge in something that would be very valuable to someone else. For example I met a guy a few weeks ago that’s 67 years old and looks like he’s 35. Jet black hair, smooth skin…etc. Honestly, he has the fountain of youth. When I asked him about it he tells me that it’s a vitamin regimen he started when he was 30 years old. That’s valuable information though he doesn’t recognize it as such. Even guys like my brother-in-law that knows how to fix a broken washing machine. That is sure valuable to me when the time comes for that. Everyone has their own valuable information, specialized knowledge or “Magic”. Something that they know more about than 95% of the rest of the population.

For me, my “Magic”, is how to build highly tailored, custom PCBs that communicaste over networks like DeviceNet, Profibus, EtherNet/IP, ASi Bus and a bunch of others. We make custom DeviceNet PCBs, Highly Tailored EtherNet/IP IO Modules, AS-Interface Boards for valves, conveyor lines, drives and and lots more. (You can click any of these links to see examples of the kinds of things we do.) What I always fail to realize is how incredible most of the rest of the population thinks that is. I went to an Entrepreneurs forum a few weeks back and held up this little Freescale Coldfire processor based board and these folks looked at me like I was Moses coming down the mountain with tablets.

I never think about this as specialized knowledge but my mechanical friends sure think it is.  He makes the great point that when he builds a mechanical system, people look at it and say, “Well, of course you did it like that, it’s obvious”. And then he fumes asking them why they didn’t propose that solution before he put it together. On the other side of the fence, he complains that when I build a PCB, people ooh and aah about it, like the people I just mentioned, because it looks so difficult and mysterious to them. His stuff just looks like obvious. “It’s just not fair” he complains. My response to him, was that he could have been an electrical guy…but he choose mechanical so DON’T COMPLAIN.

What is your specialized knowledge? What “Magic” do you possess? It might be something as important as parenting or something mundane like how to tune up a bike after a long winter. No matter what it is, it’s a good thing to ponder what you know that other people would like to know and how you should go about letting people know that you have that Magic.

Drew B, the creator of Instant Automation Man, and I attended the Upper Michigan AOTM Event last week at the Soaring Eagle Casino way up in Mount Pleasant Michigan. It’s a ways to go but your typical non-vegas casino. Every variety of frail old men and women you can imagine. Blue hairs, wheelchairs, walkers and oxygen tanks blocking the aisles. I was surprised that I didn’t see any hospital beds or oxygen tents but maybe I just didn’t hit that part of the casino.

I did two afternoon sessions on Industrial Networking and covered the gamit; ASi, Modbus, DeviceNet, EtherNet/IP, Profibus, Modbus TCP and ProfiNet IO. It went pretty well but I always forget how complicated this stuff seems to the uninitiated. For me, well I’ve been doing this for a hundred years, it’s all straightforward. I forget that most people don’t know much more about this stuff than how to hook up the cable. It takes me a while to dial back and help people get some idea about all these networks. Ace Marketer Drew will have a video and a transcript of the presentation up next week.

The newest part of the gig was a section on EtherCat. The more and more I study it the more I like it. It’s fast, reliable, physically easier to wire and easy to understand. It’s apparently growing like crazy. You can expect to hear more from me about this in the near future.

JR