This podcast was recorded in 2015, and is being re-published in case you missed it!
This week we are proud to welcome John Rinaldi, the founder of Real-time Automation and the author of the book Industrial Ethernet as well as OPC UA: The Basics, An OPC UA overview for those who may not have a degree in embedded programming. He has also written a book on Modbus. All these books are available on Amazon.
John Rinaldi is the founder and President of Real Time Automation. John Rinaldi has a Bachelor of Science in Electrical Engineering and a Master of Science in Computer Science.
Q: Tell us a bit about your background and more about what Real-Time Automation does.
Real-Time Automation is a product development company for Control Engineers, System Integrators and IT application developers with factory floor data communications. We provide the infrastructure to move data across the factory floor. That’s our mission and what we love doing and have been doing for 30 years now. I have a big sing in my office now that says “Keep it Simple”.
Q: How did you get so passionate about factory communications and Ethernet/IP?
That comes from a love of helping people. People would call up with a problem where they have data from one source and other data from another that they wanted to get into an Excel spreadsheet. For example, someone called the other day and said “I just have six variables in an Allen-Bradley PLC and I just need to move them to Excel, but I don’t want to buy RSLinx or OPC; isn’t there an easier way to do something simple like that?” I love those kinds of calls, and I love solving those kinds of calls. Today there are no Islands of Automation – everything needs to be connected, and we’re here to solve those problems.
Q: I see that business increasing as well with IoT and IIoT becoming more prevalent.
There are a few things that we’re working on for the coming years. The first is legacy communications. There are a lot of older systems that are being obsoleted, but these plants are everywhere all over the world! Customers can’t afford to rip out these systems and start all over again, so we step in to provide the tools to maintain these systems until it makes economic sense to change them. We are also working on the standard business of connecting data across the plant floor. The third aspect of what we’re doing is working on the IoT systems. We want to be the pipe that pulls data off the factory floor and sends it off into the cloud.
Q: Why are there so many different protocols on the plant floor?
The million dollar question. I had an engineer tell me “Standards are wonderful, everyone wants their own.” And it’s true – people want to build something on their own. In the old days, the bigger companies wanted to lock customers in with their own standard. Then we moved to open standards, but there was a move to create specialized protocols. Yes, it’s a nightmare for those of us trying to move data around, but there’s not much you can do about it and it’s not going to change, so I guess that means that I’ll be in business forever.
Q: what are the advantages of Ethernet/IP versus other protocols like Modbus, Profinet, etc?
Let’s start with the different types of protocols we have. We have the low-I/O protocols, messaging protocols meant for messages rather than I/O data. When you talk about I/O data there’s not a lot of difference between Ethernet/IP and Profinet because they accomplish the same thing. There’s a block of data out there in the remote device, and the protocol moves that data into the controller. There’s a block of outputs in the controller and it moves it to the device. That happens over and over again, very quickly. There’s really nothing that makes Ethernet/IP that much better for I/O data. Messaging protocols just move messages back and forth, so Modbus doesn’t have the connection to move the data back and forth. The third type of protocol we have now is something like OPC UA, which moves information back and forth, which is different from moving I/O data. So for example, OPC UA moves information such as how much energy a motor has used in the past 36 hours, vs. the status information on whether or not a drive is on or off for an I/O protocol.
Once you know that, you can look at it in terms of which group of protocol it is, and within a group most are complementary. The main difference is from category to category. Within categories you can choose based on what equipment you’re using, what people know and are trained in, etc.
Q: Tell us a bit more about the monitoring protocols you brought up.
With monitoring, the information protocols are really the best. With information protocols you have the opportunity to ask for different information depending on what you’re monitoring. When talking about something like Ethernet/IP, this is a perfect segue way into implicit vs. explicit information. When I was talking about moving I/O blocks in and out of a device, that’s what Ethernet/IP calls Implicit communications. There’s a big block of data, and that data gets exchanged over and over very quickly.
Explicit communication is an exchange where you can actually open up the packet and look and see what it says. In Ethernet/IP, all the data is organized around objects. So if you have a meter and you have temperature data, you’d put all the temperatures in the temperature object. So that can come back as the implicit I/O message, or, for example, explicitly read the second attribute of the temperature object. With explicit messaging you can read individual items. Now this isn’t good for monitoring, because even though you get that data in the PLC, it’s stuck in the PLC. PLCs haven’t been very good about moving that data into the enterprise software or the cloud, or the IT ends of applications. They’re going to get better in the future, but for now it’s not a good way to handle monitoring. You’ll still want to use an information protocol like OPC UA to do that kind of monitoring.
Q: Can both Explicit and Implicit communication be implemented using TCP and UDP?
Explicit messaging is always TCP and implicit messaging is always UDP. The difference between TCP and UDP is that TCP is always acknowledged communications. If you are reading a device with explicit communication and the message gets lost, the user will want to know that it’s lost. With implicit communications which come regularly every 10 milliseconds, it’s not important to know if one gets lost because you’ll get another in 10 milliseconds.
Q: What is the difference between Ethernet/IP and CIP?
CIP is the Common Industrial Protocol that creates the structure for information arranged around objects, and the common services that operate around those objects. So if there’s a CIP message to read the data around a certain object and you send that CIP message over Ethernet, then that’s Ethernet/IP. If you send that message over Can, then that’s DeviceNet. So CIP is the common data representation and services in all the ODVA protocols. Theoretically it’s true that you could pick up the same message and put it over Can or Ethernet and the device would know how to react to it.
Q: Why do some devices not support communication with each other even if they all support Ethernet/IP?
Devices are either scanners or adapters. Scanners are devices that initiate communications and speak to an adapter device and dictate the messaging. So it’s set up for scanner to adapter type communications. So for two adapters to talk, there needs to be something initiating communications. There’s no pure messaging in Ethernet/IP. There’s always a scanner talking to an adapter. Now, a scanner can also be an adapter, but that’s really a special case that we don’t see very often. Two scanners also don’t really talk to each other. There are really no peer communications in Ethernet/IP and the same is true of Profinet and these similar clients.
Q: If I want to get more information about Ethernet/IP, where would I go?
There are a number of places you can go. One of the best is our website, RTAAutomation.com. There’s a Technology section about Ethernet/IP with a lot of good information. I’ve written several papers on Etherne/ IP as well. Another place is the ODVA website, ODVA.org. And in 2016 I’ll be releasing a book on Ethernet/IP that should be a pretty comprehensive look. There are also a number of YouTube videos that I’ve done.
Q: Can you tell us a bit about some of your books?
The Industrial Ethernet book is a comprehensive overview of everything you need to know about Industrial Ethernet for the non-engineer reader. The OPC UA book is like the Readers’ Digest version. It’s less complicated than the official version. Then I wrote the Modbus book while I was in Paris, which is an overview of Modbus. The book I’m working on now is a much more comprehensive view of OPC UA. I’m working right now on explaining security, which is such a broad and complex topic.
Q: What advice do you have for someone entering the industrial automation industry right now?
There’s no better time for someone to come into industrial automation. Baby boomers are nearing retirement, and the field is open. If you understand a little bit about IT, control systems, how to program PLCs and set up IT systems, I think you have an unlimited career path in front of you. It’s a wonderful time to have that kind of background. The current group of control engineers don’t know IT and don’t want to know it, and the IT people don’t know anything about control systems. If you can bridge that gap and have one foot in IT and the other in controls, you’re going to have a wonderful career.