Communication standards keep machines in line
Communication is the key to effective teamwork. That goes for machines as well as people.
Successful integration of a packaging line depends on compatibility in electronics as well as mechanics. That’s why connectivity standards constitute one of the most important factors in line integration. The electronic controls that communicate along a packaging line and pass data to higher-level systems are becoming increasingly standardized, and this standardization is a key element in being able to put together a line quickly and reliably.
But there still is a long way to go.
When it comes to electronic connectivity in a packaging line, there are two basic, broad issues: What kind of information will be communicated, and how. These issues involve both software and hardware, and affect everyone involved in making and installing packaging lines: equipment manufacturers, controls manufacturers, integrators and end users.
To put it simply, to coordinate a packaging line, the components-the individual machines-have to be able to communicate what they’re doing. Specifically, they should be able to “tell” other machines, as well as higher-level information systems, what their current status is. To do that requires a common programming language.
Connect-and-packOMAC (the Organization for Machine Automation and Control) has a subgroup called OPW (OMAC Packaging Workgroup) that is dedicated to developing conventions for these kinds of communications. These conventions are grouped under the names PackML (Packaging Machine Language) and PackTags. At their core, they consist of a series of descriptions of machinery states, such as stopped, starting, running, suspended, executing commands and completed. These can serve as the basis of a common machinery programming language. The ultimate goal is what OMAC describes as Connect-and-Pack Guidelines (a trademarked term), which would, at least in theory, allow packaging machines to be connected as easily as a home computer user can connect a printer to his desktop PC.
At present, PackML and PackTags are implemented mostly via equipment controllers, usually programmable logic controllers (PLCs). Most PLCs and other controllers come as part of the total machinery package, which sets up a triangle of responsibility for implementing Connect-and-Pack: control vendors, machinery suppliers and end users.
David Bauman, OMAC’s technical director, says that so far, the end users are creating the most demand, on a pull-through basis, for PackML and Connect-and-Pack.
“The driver really started from the end users, because the users are the ones who are really trying to get an integrated packaging line,” Bauman says.
One of the problems with that approach is that individual end users, even huge consumer goods companies, have limited influence when they approach the issue on a per-project basis.
“Individual companies going to individual machine builders–it’s a one-to-one battle to try to get the person convinced on using PackML,” says Mike Jamieson, Rockwell Automation’s global director for the consumer packaged goods industry. “One of the things we have to figure out is, how do we work collectively so it’s win-win for the machine builder and the manufacturer.”
Start with controllersThe drive to implement PackML starts with a machine’s controllers. Rockwell, for example, has the PackML state model built into many of the controllers in its Logix line. But since, in most cases, original equipment manufacturers (OEMs) are responsible for specifying the controllers that run their machines, they’re the ones who usually need to green-light PackML. And there’s a certain amount of resistance, especially when they’ve developed their own programming language and standards.
“The machine builder often just sees [PackML] as a cost,” Jamieson says. “They have to rewrite a lot of their coding standards they could have had for a number of years, even though over a longer-term period, PackML adoption can drive significant cost savings for them.”
Control vendors like Rockwell are in a position to help implement such standards, Jamieson says: “We’re kind of like the guy in the middle. We’re part of the standards body, we work with the manufacturer and we work with the machine builder to make sure both are on the same path, so when they do come together, the end user’s asking for the correct standard and the OEM is building to the correct standard.”
The advantages of connectivity extend beyond machine-to-machine linkage. By tying into management software such as manufacturing execution systems (MES) or enterprise resource planning (ERP), and by incorporating sensors, vision systems and other non-mechanical components, a PackML-based system can enhance oversight and troubleshooting.
“I call it ‘connect the dots,’ because if you have the PackTags defined on your MES or ERP system, and the same way at your machine level, it’s just connecting the right information together to get an integrated packaging line,” Bauman says.
DiagnosticsBringing sensors into the system is especially important when it comes to diagnostics, Jamieson says.
“If I have a problem with rejects coming off my labeler because I’ve got problems with my glue, I want to be able to diagnose that quickly,” he says. “When you’ve got a line running 1,000 or 2,000 bottles a minute, you want to have a system that can pull all that richness of data from that integrated system and turn it into information, so you can find out what your root cause is and drive continuous improvement.”
The potential for improvement is high. OMAC says that a packaging line with Connect-and-Pack status would enjoy an overall equipment effectiveness of up to 90%, compared with 50% to 60% under current industry standards. Other potential advantages include greater flexibility, the ability to control entire lines through a single interface and reductions in inventory of 33% or more.
At its recent Automation Fair, Rockwell presented the case of a greenfield Cadbury chewing-gum plant in Poland. The plant’s equipment came from more than 17 machine vendors, all of whom conformed to PackML and associated standards for both packaging and processing.
“They had to spend a lot more money up front to drive these standards into the machine builders,” Jamieson says. “These were new standards for those OEMs, so obviously they cost a lot more money. But the key thing was, they saw a dramatic improvement in the start-up time of the line. Every machine builder’s skid was plug-and-play. They had the same code standards, the same look and feel for the data, the same visualization for the line. Every machine plugged together and started up with little or no effort. That gives a dramatic cost saving, because you can have salable product far earlier than you would have done.”
New SERCOSOther aspects of industrial electronics have made progress toward uniformity. One of the most notable such steps was announced at last fall’s Pack Expo show in Chicago. The digital communication standard known as SERCOS (Serial Real-Time Communication System) is coming out in a new version, SERCOS III, which will be compatible with the Ethernet communication protocol.
SERCOS is an interface that connects motor drives and controls, plus other automation devices such as input/output (I/O) points, actuators and sensors, via a common language. It’s administered by SERCOS International e.V., a Swiss-based non-profit group, and supported by an assortment of equipment and controls suppliers. SERCOS International had worked with OPW, the OMAC Packaging Machinery Workgroup, to develop SERCOS II in 2005 as a standard that could carry PackML information. SERCOS III is an advance on that standard. The major improvement is that SERCOS III is designed to work with EthernetIP, which is rapidly becoming the most common industrial data protocol.
Peter Lutz, managing director of SERCOS International, told the Pack Expo audience that the group had decided to develop SERCOS III to work with EthernetIP last year. As a result, SERCOS III has significant operational advantages over earlier versions. It has a data capacity of 100 megabits per second, up from 16 for SERCOS II, and has a cycle time of 31.5 microseconds, twice as fast as before.
In practical terms, these improvements make for easier wiring, which in turn will make an integrated system easier to establish and more reliable. A conventional system requires separate buses (wiring paths) for motor drives, I/O points and diagnostic or safety-related data. SERCOS III over Ethernet is a deterministic system, meaning it can handle different types of data on a single bus and give priority to the data that has to move in real time.
In addition, a SERCOS III system can send the same data in both directions (clockwise and counterclockwise) around a ring (looped) bus, which confers redundancy, making the data more secure. If the ring gets broken due to equipment failure or other causes, SERCOS III can instantly convert to a line topology, allowing the data flow to remain uninterrupted. Perhaps most important, it allows direct communication between individual PLCs or other controllers, without having to send the data via a master device like an industrial PC.
The bottom line in electronic integration is that the end users, the ones buying the machinery, have to insist that standards like PackML and SERCOS III be incorporated, Jamieson says. And that means, in turn, that they might have to be willing to pay a little more up front.
“Ultimately, it’s a cost to someone to take this approach to standardization to help with line integration,” Jamieson says. “And most companies nowadays are going the other way, toward low-cost procurement. Not many companies are taking the approach of spending more upfront, which is a shame, because the total cost of ownership, the ability to start up that line on time, the ability to maintain that line easily going forward…that is worth a lot more to a company than the savings they make on the front end.” F&BP
SIDEBAR: Who will tie the line together?When it comes to line integration and compatibility, electronics has seen a lot of action, but there are other important aspects. One of the most basic is: Who’s going to do the work?
Putting together a new packaging line, or making substantial changes to an existing one, is an engineering task that is both demanding and rare. For most end users, it’s too rare to justify keeping engineers on staff just for that purpose, especially in bad economic times.
“In the last two years or so, with the general economic situation, there have been changes to corporate engineering departments that have made companies outsource line integration,” says Gary Lange, vice president for sales at Nalbach Engineering Co.
End users looking to outsource integration have two major options: independent specialists or machinery manufacturers. The former comprises everything from single individuals (many of whom went into business for themselves after being laid off from large companies) to long-established engineering firms. The advantages of independent integrators include a broad array of services and objectivity in specifying equipment.
However, many equipment manufacturers offer integration services that are completely independent of their sales function, enabling them to claim just as much objectivity as independent integrators. Tim Lewis, manager of Jones Integration Services, a unit of the R.A. Jones & Co. div. of Oystar Packaging, says there have been integration projects where Jones has specified competitors’ equipment (although this equipment has been outside of Jones’ core competencies, such as cartoners).
“It doesn’t make me the most popular person in the building, but if it’s the right thing for the project and the customer, that’s what we do,” Lewis says.
One of the biggest challenges for an integrator is coordinating procurement issues between the end user and the equipment suppliers, Lewis says. These include aspects like intellectual property rights to equipment and software, limits of liability and how much time is allowed to resolve any problems.
This kind of coordination has become more challenging in recent years, Lewis says: “There are more legal issues, because more companies have become litigious because of problems they’ve had.” When an integrator’s contract with an end user specifies how much time is allowed to resolve problems and what consequences will ensue if the project falls behind schedule, the integrator has to pass those requirements back to the equipment manufacturers.
“There’s a lot more focus and strength in the purchasing departments than in engineering” among end users, Lewis says.