Newspapers and Technology March 2000
Open architecture control, Part I: What it means to newspaper production
By Jim Hulman
Connectivity and interoperability of hardware and software from competing vendors is taken for granted throughout editorial, circulation, prepress and enterprise computing applications. But what impact will open architecture have in the presroom and mailroom?
Press control networks go open
Today's press control systems rely on open architecture control platforms such as Ethernet for interfacing to production management systems, and Profibus or Devicenet for interfacing to distributed control modules and receiving inputs/outputs from scanners and other auxiliary devices.
Press drive networks go open
The good news is most shaftless press drive systems today are based on open architecture interfaces. This is because shaftless technology was developed after the advantages of open architecture became apparent.
The bad news is as more drive suppliers enter the shaftless market, proprietary interfaces are beginning to appear. It is up to the press or mailroom equipment purchaser to specify open architecture control networks or become limited to one drive supplier's products.
Proprietary control networks
Before the advent of digital drives and devices, a simple, low-voltage analog signal controlled motors. However, shaftless press drives require the performance of digital servo drives, digital control and digital communications. Using an analog interface on a digital drive is comparable to connecting a low-resolution picture tube to a high-definition TV receiver.
The first digital drive interfaces were proprietary because each supplier worked out their own system. As with the Commodore 64 computer that may now be in your attic, early innovators had no standards to follow. But eventually, the need for standards became clear if personal computing was to go mainstream. The same was true for digital servo drives, on which all shaftless technology is based.
By the late 1980's, servo drive suppliers had developed a standard to present to the International Electrotechnical Commission. This standard, called Serial Real-Time Communication System or SERCOS, is now available from most major U.. and European drive suppliers, plus a small but growing number of Asian suppliers.
Vendors who continue to offer a proprietary solution instead of a standardized interface do so to artificially protect their margins and their market share, knowing that other brands are not interchangeable with their drives and controls.
Open control: life cycle cost benefits
Open communications -- including Ethernet, digital field buses and SERCOS shaftless drive systems -- provide new communications capabilities that range from Web-enabled production monitoring to predictive maintenance scheduling. Open drive interfaces also make it easier to implement perfing, cutting and other value-added in-line production capabilities from third parties on an installed press. Open interfaces also minimize spare parts stocking and training of personnel.
Synchronization
Standard interfaces also simplify communications between press controls and mailroom equipment. As mailroom equipment goes shaftless, it will become possible to tightly synchronize the inserter with the folder, so that zoning can be accomplished faster and with less waste.
Specifying drive systems from vendors who conform to the SERCOS standard assures that these two systems can operate together, and at the highest possible production rates.
Retrofit strategies
Over the press' life cycle, perhaps the greatest cost advantage of the SERCOS interface is the flexibility to mix-and-match different makes and models of add-on units to presses and the ability to implement value-added capabilities to your press for years to come.
With a proprietary shaftless drive interface, it is not feasible to interface a shaftless drive if the existing press drives come from a different supplier. In fact, it is actually less of a struggle to engineer a mechanical add-on.
As page and color capacity increases, it becomes necessary to add print units. To add units of a similar drive interface, you add another node to the drive network. It is impossible to combine different drive interfaces due to the highly deterministic nature of a synchronized control system.
In the case of combining equipment with different drive interfaces, you actually rely on a mechanical interface. The secondary drive system follows an encoder that is mounted to the existing mechanical press. To some, this may seem feasible, however this has limitations.
The best synchronization is achieved when all drives are synchronized to the same reference. When following an encoder that is mounted to the existing press there is inherent lag or delay. Consider following a person down the sidewalk. You cannot predict a direction change. You have to wait until after the person initiates their change in direction before you are able to start your change. The same delay is present when the person stops. This is the same reason automobile rear-end collisions occur on our highways. With a following arrangement there will always be some inherent lag.
Enabling preventive maintenance
The SERCOS service channel lets intelligent drives communicate a wealth of diagnostic information to avoid unscheduled maintenance.
Changes in torque, position, velocity and temperature values give indications of wear on various press components before the press goes out of tolerance or breaks down. Several computerized maintenance programs are on the market that can use this information.
What is open?
This has been the subject of endless debate among technologists. Fundamental criteria are:
- Documentation is publicly available at a reasonable cost
- A substantial number of mainstream suppliers support the architecture
- Test procedures are available to assure a minimum level of compatibility between vendors.
As a result, Microsoft operating systems are termed de facto "open," even though they are owned by Microsoft, since they meet the criteria above for PC makers and software developers.
If Microsoft did not open its programming interfaces to these third parties, their operating systems would not have gained such strong acceptance. Apple's growth was severely limited by shrinking support from software developers for its Mac OS. The company's current success is being derived from its Internet-focused iMacs. The Internet, of course, represents an open communications interface that is independent of operating system.
That's why programmable controller makers have put their field buses in the public domain, and why SERCOS was cooperatively developed by servo drive makers.
Users groups formed
Major users of web processes ñ notably packagers, packaging producers and paper converters -- have formed a working group of the Open, Modular Architecture Controls Users Group.
Anchored by the chief automation specifiers at consumer products companies that purchase billions of dollars of machinery each year, OMAC can give publishers enormous leverage with manufacturers to engineer open architectures into their designs. Just as newspaper publishers have a track record of contributing to the common good, OMAC members are doing the same today.
Shaftless drives are now being used in packaging, converting and printing, so this initiative relates directly to the newspaper industry. The users group members are establishing technical guidelines, so newspaper publishers needn't ask their lean technical staffs to reinvent the wheel.
Cost justification model completed
In 1999, the OMAC Users Group completed an open control cost justification model to calculate the return on investment resulting from open architectures. It covers different phases of implementation, for machine builders as well as users, along with life cycle costs. The open control cost justification can be found at: www.arcweb.com/omac/guidelines/BusJustV1.pdf
Few enterprises are as dependent on a single piece of production machinery as the newspaper industry. It is a small investment to study the benefits of specifying open architecture drives and controls for shaftless printing and mailroom equipment. And one that can have a measurable return.
SERCOS
800.573.7267 or 630.351.4881
www.ercos.com
OMAC Users Group
www.arcweb.com/omac