Communicating with the Shop Floor
The promise of better data interoperability pushes efforts to improve manufacturing industry's factory-floor communications
By Patrick Waurzyniak
For years, the manufacturing industry has debated the pros and cons of opening up manufacturing networks, but concerns over virus vulnerabilities and the stability of PCs on the network largely limited open-architecture PC controls’ progress and kept entrenched proprietary systems in place. In networking and communications, machine tool and control developers mostly rally around Ethernet/IP (Ethernet/Industrial Protocol) and other commonly accepted communications methods as the industry’s standard for sharing manufacturing data and for key applications including machine monitoring and shop-floor data collection.
A relative newcomer to the industry, MTConnect brings an open-source, royalty-free manufacturing protocol designed to easily connect manufacturing equipment to the outside world using proven Internet standards such as HTTP (Hypertext Transfer Protocol) and XML (Extensible Markup Language). The lightweight MTConnect protocol defines the structure of data in XML documents via XML schemas, specifies machine tool components and the data streams that can be provided by manufacturing devices, and most recently, a description of cutting tools, workholding and fixturing systems.
Introduced formally by The Association for Manufacturing Technology—AMT (McLean, VA) at IMTS 2008, the MTConnect Institute (McLean, VA) is still building momentum in the industry, with a significant, growing list of members that, as of July, included machine tool builders DMG / Mori Seiki, GF Agie Charmilles, Hardinge, Hurco, MAG, Makino, Mazak, and Okuma; machine control suppliers Bosch Rexroth, Fanuc FA, and Fagor Automation; robotics builder Fanuc Robotics; tooling developers Kennametal and Sandvik; software developers CAMWorks and Predator Software; and consultants with the Georgia Tech Factory Information Systems Lab, the National Center for Defense Manufacturing and Machining, the National Center for Machining Sciences, TechSolve, and others.
"MTConnect is something fairly new. It’s maybe something the machine tool vendors are going to embrace—not everybody’s on board," says Greg Mercurio, president, Shop Floor Automations Inc. (La Mesa, CA). "In some aspects, there has to be some type of standard. In the PC world, Windows is a standard; when we look at our keypad on our phones, it’s pretty standard. Unfortunately, in the machine tool world, everybody builds their machine tool controls differently and they use different communication methods, so the idea is that MTConnect is trying to set the standard communication method to retrieve data from equipment."
At IMTS 2010, MTConnect and OPC Foundation (Scottsdale, AZ) announced that the organizations would cooperate on developing standards, called MTConnectOpcUa, a set of companion specifications to ensure interoperability and consistency between MTConnect specifications and OPC specifications. And with its recently introduced third release, MTConnect Version 1.2 has added assets such as cutting tools, workholding systems, and fixtures, all elements associated with the manufacturing process that are not components of the device and can be removed.
"In the machine tool world, everybody builds their machine tool controls differently."
"Up until this release, MTConnect was all about things connected to the machine tool," notes MTConnect Institute President and Chairman Dave Edstrom, who recently spoke in-depth on the topic of shop-floor networking and communications at the DMG / Mori Seiki USA Inc.’s (Hoffman Estates, IL) Innovation Days. MTConnect v1.2 gives concrete examples of cutting tools that conform to ISO 13399, the standard for describing product data regarding cutting tools, independent of any particular system, he adds. In addition, the updated standard describes the modeling of these assets and the management and communication of asset data using MTConnect.
Why Should Manufacturers Choose MTConnect?
Manufacturers are looking for plug-and-play networking solutions that are easy to connect and deliver critical manufacturing data in real time to plant management, Edstrom notes. "For shop floor owners or plant managers, lean manufacturing requires shop-floor monitoring. My take is that it’s impossible to do lean if you don’t do shop-floor monitoring," he says.
"Customers are really demanding a plug-and-play solution," Edstrom states. "Their challenge is taking that data and turning it into actionable information."
The MTConnect specification is not an application, but it’s a read/read protocol that Edstrom says makes it extremely simple to connect machine tools to factory networks. Older legacy machine tools will need a black box type of adapter and an agent, which is software code that enables the devices to communicate. Newer CNC machines will need just a built-in agent to employ MTConnect. "Think of MTConnect as the Bluetooth for manufacturing," Edstrom says. "Essentially it makes our machines look like a Web site.
"When you look at all the things going on out on the shop floor, you want to get some of the simple things," Edstrom says. "One of the interesting applications with CAM vendors is to see exactly how much it costs in energy to make a specific part."
"Think of MTConnect as the
Bluetooth for manufacturing."
MTConnect offers the source code and binaries free to machine tool companies, which can decide whether to offer MTConnect-enabled applications free to customers or to instead charge a fee for the implementation. At the Innovation Days, Surya Kommareddy, manager, DMG / Mori Seiki USA Qualified Products (DMGMSQP)-software, described the company’s MTConnect solution, which currently is based on MTConnect v1.1. The implementation includes an adapter with a MAPPS option for each machine to collect machine data; an agent, consisting of software on the customer’s PC to transfer machine data to the network, free of charge; and a Web server that can be hosted by the customer or by Mori Seiki.
"Think of MTConnect as a protocol pipe, connecting manufacturing equipment to applications," Edstrom observes. "When it’s MTConnected, a manufacturer has lots of options, and they don’t get locked into other drivers." Also, as a read-only protocol, he adds, "nobody can call and say ‘MTConnect made my machine crash.’"
Shop-Floor Monitoring Critical To Lean
While real-time data collection and monitoring of machine tools are essential for lean efforts, many shops don’t employ machine monitoring for various reasons, most likely due to cost considerations. But effective lean implementations depend on leveraging careful analysis of key metrics, particularly overall equipment effectiveness (OEE), which can be obtained through effective shop-floor monitoring systems (see "Managing Factory Data" in the July 2012 issue of Manufacturing Engineering.)
"Today MTConnect represents an investment. Over time, it will accelerate the number of applications and the intelligence of those applications for a wide range of manufacturers," says Jim Abbassian, president, Predator Software Inc. (Portland, OR), an MTConnect member. "As a software developer, we can certainly hope that machine builders will continue to embrace, support and provide MTConnect standard with every machine they ship.
"It depends on how aggressive everybody gets about retrofitting their existing equipment, and it also depends on how serious the builders are about shipping it," Abbassian adds regarding MTConnect’s acceptance. "The classic problem is whether it’s an extra-cost option, or is it standard with every machine? As an industry, we’ve had improved connectivity and shop-floor options for years from the machine builders, but they’re always at extra cost."
Many machine builders offer their own versions of machine monitoring, adds Shop Floor Automations’ Mercurio, but don’t adequately support it. "The key is everyone’s utilization of their equipment and productivity. As companies are getting leaner, they have to have efficient monitoring," Mercurio says. "You can ask business owners, what is the utilization of their equipment? They’ll give you an answer, but I bet it’s not accurate." The average is probably close to 50 or 60% of the time, which isn’t very good, he adds.
A network-based standard like MTConnect brings a lot to the table for manufacturers looking for monitoring OEE metrics, according to Mercurio, who has supported Fanuc’s FOCAS standard for networking for years. "If you talk to MTConnect, that’s one of the things that they can bring to the table, and OEE can be used in any industry. That’s where Predator, Okuma, all these companies are coming together and saying, ‘OK, we’ll take that standard.’ We want to embrace a standard. The other side of the coin is that more and more machine tool vendors are embracing an Ethernet connection."
Leaving SneakerNet Behind
With most machine controls today, shop-floor communications systems include USB, Compact Flash (CF) card, and Ethernet, notes Randy Pearson, dealer support manager, Siemens Industry Inc. (Elk Grove Village, IL). "USB, Compact Flash cards and Ethernet have eased the pain of getting part programs to and from the CNC," Pearson says. "USB and CF cards allow machine operators and programmers the ability to transport part programs from machine to machine quickly and easily, and since a cable is not required, setup is fast and easy. As for Ethernet, this allows the machine operator to load a part program from the programming department with the push of a few keystrokes; however, this does entail running Ethernet cable and setting up of the TCP/IP address in the CNC."
Ethernet is the dominant networking protocol used in most manufacturing facilities, Pearson says. "But on the flip side, in many smaller shops, USB and CF cards seem to be the preferred method," he adds. "Siemens includes these options in all its control platforms. USB and CF cards are basically plug-and-play, while Ethernet requires some setup and cooperation from facility IT personnel." Ethernet and ProfiNet are industry standards, he adds, and therefore compatible worldwide. "Ethernet is used for the communication to an external computer that stores the machine tool’s part programs offline," he says, "while ProfiNet is used for internal communication of the control hardware and peripheral devices."
Whatever the version of fieldbus communications—either Ethernet/IP, ProfiNet, Modbus, TCP/IP—a global supplier like Fanuc will support it, notes Paul Webster, manager, CNC Engineering, Fanuc FA America (Hoffman Estates, IL). "Ethernet IP is dominant in the US, but it's gaining acceptance worldwide. However, there are also other fieldbuses that we support, including Profibus, ProfiNet, FL-Net and Modbus.
"The important thing is these are all Ethernet-based fieldbuses," Webster says. "What they give us is the ability to use a generic Ethernet cable to transfer your I/O points, and over that same cable, we can transmit discrete I/O and data. An example of data transfer is using Fanuc's FASConnect, a software solution for network distributed data management, that allows CNC data management of all the machines in a factory from any computer on the network."
Fanuc FA and Fanuc Robotics are both MTConnect members and also are Technical Advisory Group participants of the consortium. "As far as a protocol itself, it’s similar to any other protocol. It’s just another way of communicating with a CNC," Webster observes. "There are already several available. Fanuc uses what’s called FOCAS [Fanuc Open CNC API Specifications], that’s our native protocol.
"Pretty much everything that’s available in the CNC is available through FOCAS. MTConnect is written to be an industrial protocol across manufacturers. The advantage here is that you get the same data from all CNCs in a factory, but the type of data you can acquire is limited."
With a protocol like Fanuc FOCAS, users have access to more data than with a generic protocol like MTConnect, he adds. "So you can get anything you want," Webster adds, "if you write an application in FOCAS."
MTConnect’s approach does have some conveniences, he adds. "The XML-based information is man-readable, and it’s readable by generic Web applications," Webster says. "But because we’re talking about something that’s going over Internet-style communication, it’s not particularly fast. FOCAS is written specifically for the CNC, so it’s much faster."
The protocols execute data in a different manner as well, he says. "One’s an API, while XML’s a flat file, basically like a text file," Webster says. "You’re sending flat files back and forth, which isn’t as quick as making a call to a bit or a byte or a word. You have to create it, then send it, and then translate it on the other side by the application. But it’s generic, so that XML data can be sent to anybody, and used by any application, basically, as long as you know what the data is that you’re receiving means. So it’s simple. Usability depends on your application and what you are looking to do." ME
This article was first published in the August 2012 edition of Manufacturing Engineering magazine. Click here for PDF.