t’s a new year and lists are all over the place. Lists of biggest political gaffes, biggest sports upsets of the year and, one of my favorites, the list of notables that have passed on this year.
So, I thought I’d start the year out with a list too. In my case, I like to make my list of the biggest myths that surround Industrial Ethernet.
Myth 1: Multi-Protocol Access
Lots of people believe that if you’re running Profinet, IO it somehow ties up your Ethernet port. That’s a myth left over from the old serial communications days. With a serial protocol, if you’re running Modbus or a proprietary protocol, the port isn’t available to anything else. But with Ethernet, it’s completely different. In fact, right now you are probably running Outlook, a couple of web browser sessions and maybe an HMI - all Ethernet applications just like EtherNet/IP, Profinet IO and Modbus TCP. There is no reason in the world that if you support more than one Industrial Ethernet application layer you can’t be connected to all of them at the same time.
Myth 2: ControlLogix can be an EtherNet/IP Server
Many people believe that you can open a ControlLogix or CompactLogix PLC as a Server on an EtherNet/IP network and it will serve up I/O messages to you. That’s completely false. Logix PLCs are not I/O servers. You can open EtherNet/IP connections to them and explicitly read all the required EtherNet/IP objects, but they won’t produce Inputs or consume your Outputs. (By the way, I am pretty sure that Siemens PLCs act the same way on a Profinet IO network but I’d have to test that to be sure.)
Myth 3: 100Mhz Ethernet is better than 10Mhz Ethernet
This reminds me of the Control Engineer putting 100Meg Ethernet in his plant. He had to have the speed that the 100Meg brought him. Trouble was he had injection molding machines dropping a part out every 22 seconds. He probably could have used 300 baud serial to capture that part data. Unless you have a massive number of devices, in most cases higher bandwidth Ethernet won’t buy you a lot in performance.
Myth 4: Profinet is non-standard Ethernet
This has been around for a long time. I don’t know who says this but a lot of people believe it. The problem is that there are three Profinet implementations. Component Based Automation (CBA) is an open architecture peer-based control system that almost no one uses. Profinet IO is the PLC-centric one that most people use and Profinet IRT is the high performance, low jitter one for motion control applications. IRT devices almost all have switches built into them to get the high performance. That’s probably where this myth originated. Profinet CBA and Profinet IO use standard Ethernet cabling and switches.
Myth 5: The __________ protocol is better than __________ (fill in the blanks)
This is my personal favorite. I have never, ever known a plant to select an Industrial Ethernet protocol by evaluating its characteristics and performance. Never. It just doesn’t happen. People pick Siemens, Rockwell, Groupe Schneider or some other platform and then use the network that comes with it. Occasionally, some group like Chrysler will get mad at Rockwell, throw them out and bring in Siemens. Eventually, they’ll probably tire of Siemens and get Rockwell back. Most all of this stuff is very close in performance, functionality and support. People like what they like, and unless the vendor really screws up they stay with what they’ve had. It’s just too darn costly to make huge changes in control architecture.
Myth 6: The guzinta - guzouta myth
A lot of people that have a serial communication background just don’t understand connected messaging. Admittedly I don’t get this as much as I use to but there are people out there that just want to know what goes into my device (the guzinta) and what do I send back (the guzouta). The fact that there is a connection, that devices have to run state machines, and the whole idea of variable data representations seems to be beyond these people.
Myth 7: My Programmer says we can get it done in a month!
I love this one. Developers want to develop. Programmers want to program. I get that. But somebody in management needs to have some balls and some common sense. Why take the risk to develop software that you can buy? Don’t you have anything else for your software engineers to do? It’s never the initial development time. They can always get something to work – but it’s never one month. Later, when you go to deploy it at the customer site, is when you have to learn all the lessons that are built into the software that’s off the shelf. You end up learning those lessons at a customer site. Very risky. Damaging to your reputation and very, very expensive. But I have no doubt that it will be repeated again and again in 2012.
Myth 8: V6 is going to change the world
IPV6 is impressive. It’s rolled out to all the new desktops and laptops. It’s the standard in China. There’s a lot who recommend it. Better Security (IPSEC). The vast address space means better end to end connectivity and simpler, flatter, more manageable networks. But in a factory environment, except for security, there isn’t much of an advantage. It’ll happen but it won’t be revolutionary for us.
Myth 9: IT can’t manage the factory floor connectivity
Wanna bet? In lots of places where I go, I see that the fight between IT and Manufacturing is over. IT Won. Like it or not. IT is charged with protecting the assets of the company from internal and external threats to intellectual property. With Ethernet on the factory floor, they are going to get involved and you can bet that things are going to change. Security will have to get tighter – Modbus may finally be put to bed, forever. More open protocols like OPC UA will be demanded. In short, the factory floor in 5 years will look a lot more like an IT operation than it does now.
I have a lot more to say on all this stuff but I’m out of space and time here. Many more myths I could comment on but that will have to be it for this newsletter. If I haven’t said it before, I’d like to wish you and yours a very Happy and Prosperous 2012.