Integrated Architecture Simplifies Motion and Machine Control

It's no secret that most every manufacturer today is under the gun to get products to market faster, run their operations more efficiently, and react quicker to market shifts. If you make packaging equipment, that means your packaging line must respond in kind with machines that are fast, flexible, and reliable.

These pressures have put packaging-equipment manufacturers in a bind. Their traditional vendors tend to focus on components (I/O blocks, photoeyes, servo drives, for instance) that might address one of these issues, but not all of them. With its Integrated Architecture, Rockwell Automation is taking a system-wide approach that focuses on the entire application, and its relation to other plant-floor activities, and less on the individual parts.

Integrated Architecture focuses on the integration of control, communications, and visualization through the Logix engine, NetLinx open networks architecture, and ViewAnyWare visualization. This provides packaging OEMs and end users with several exclusive features and benefits. Here's a closer look.

Single platform for motion and machine control. Most packaging applications require a mixture of motion and sequential control. Each has different requirements. For instance, sequential applications consist of fast (millisecond) Boolean logic solving, whereas motion requires computation intensive, floating-point math as well as the need to interpolate position data and velocity.

Integrated Architecture uses the Logix platform for horizontal integration across sequential, motion, process, and drives control. All Logix controllers use a common control engine. Contrast this with traditional packaging systems that employ a dedicated controller for logic and I/O control, and a second for motion control. These controllers must be linked together using hardwiring, serial interface or some other means of communication — information is not available in real time. Naturally, this makes synchronizing and programming the system protracted and difficult. Separate application programs must be written for each controller, each with a unique programming package and language. The result is an application that is difficult to operate and maintain, exhibits inadequate reliability, and may not meet performance requirements under a variety of conditions.

Synchronizing information exchange between two independent controllers also exhausts up to 25% of program logic in each device. The amount of time it takes a data packet to travel from one processor, over the wire, to the next and through a conversion program negatively impacts accuracy. Consequently, motion and sequential control can get far enough out of sync to impact machine performance.

The Logix (both ControlLogix and SoftLogix5800) approach has several advantages. First, motion instructions residing in the processor can be used without motion cards or separate programming software. Also, interlocking motion and logic takes place in the processor for critical tasks, eliminating the need to interlock multiple motion trajectories among several motion cards across a backplane.

In addition, the ControlLogix controller now takes advantage of SERCOS high-speed digital-drive communications. It uses synchronous, distributed processing, allowing high-level motion functions to execute directly on the controller. Dedicated DSP-based motion modules perform high-speed, low-level, motion loop closure. ControlLogix executes all motion commands and trajectory planning functions. The controller can handle up to 32 axes of motion. Thirty-two embedded commands support a range of motion functions from simple point-to-point moves to more complex ratioing, position-cam, and time-cam moves.

Integrated Architecture ties all control functionality into a single, multi-tasking controller platform. This results in higher system performance, faster application development, easier maintenance, and lower overall cost. Packaging performance is enhanced because all system-control elements not only reside on the same hardware chassis, but within the same multi-processor-control architecture. The result is real-time communication and data manipulation for motion control, which yields greater precision and boosts throughput.

Single, scalable programming environment. Along with a common control engine, the Logix platform uses a single programming software package, RSLogix 5000 from Rockwell Software. Once again, this eliminates the need to purchase and maintain separate motion, sequential, and drive programming tools. The integrated motion instructions in RSLogix 5000 eliminate the need to write and coordinate two programs on different controllers, simplifying the application programming and reducing engineering costs.

Plus, shared development tools allow for the reuse of engineering resources. If a company needs to scale from one feed line to three, for instance, it's as easy as adding the necessary processors and copying code from one to the next. In a matter of minutes, the programming is complete. Having a scalable architecture allows a company to eliminate repeat work and retraining, significantly minimizing design efforts.

Integrated recipe management. Like the evolution to electrical machinery, recipe control is another packaging advancement that has compressed changeover time. In brief, recipe control allows companies to sidestep the repetitive process of tuning machines during a line change by saving and managing multiple settings. That way, the switch from a two-inch bag to a three-inch bag on a VFFS machine is a push-a-couple-of-buttons task, not an engineering design function. But once again, recipe management has been a stand-alone function with its own controller and software package.

In the Rockwell Automation Integrated Architecture, engineers can manage recipes within the Logix platform using an AllenBradley PanelView for operator interface or in more complex systems RSView or RSBatch software. The number of recipes stored is limited only to the memory of the processor. By integrating this function, the interface between recipe and motion control lies on the same backplane. So the delay between accessing a recipe to action is reduced. Which amplifies speed, which augments performance and so on.

Common HMI platform and networking services. With motion, recipe, and sequential control split, many end users are forced into several HMI solutions. They are forced, as a result, to maintain software licenses and expertise for either different companies or different software packages, depending on the size of the application. Bridging the gap between the platforms increases training costs, decreases productivity, lessens connectivity, and reduces the ability to customize.

Rockwell Automation developed its ViewAnyWare strategy — the visualization component of Integrated Architecture — to deliver a unified and scalable suite of monitoring and control solutions. All ViewAnyWare products are platform independent and built on a central configuration environment, RSView Studio. This makes way for a significant cost reduction and improvement in development time, plus an ability to reuse applications on different platforms in order to meet new requirements.

In terms of communication, NetLinx is the open networking strategy for Integrated Architecture. Designed for industrial applications, NetLinx networks - DeviceNet, ControlNet and Ethernet/IP — provide a common set of services, enabling the user to: exchange data for fast and precise control; configure systems and devices; and collect data for trending or analysis.

System bottlenecks are eliminated because NetLinx leverages producer/consumer network technology to provide a high performance, deterministic, and distributed solution. Within a Logix chassis, this flexible architecture permits multiple processors, networks (including SERCOS) and I/O to be mixed without restrictions. And as your system grows, ControlNet or Ethernet/IP provides the link to distribute control to additional chassis. With NetLinx, the right data is available at the right place at the right time.

Plant-wide integration: horizontal and vertical. The benefits of integrating all elements of a packaging machine — control, networking, and visualization — have been outlined. For the same reasons, it's advantageous to connect every piece of equipment across the plant (a.k.a. horizontal integration). This allows the packaging department to communicate with the batch process that's making the cereal and the shipping department that's waiting for cartons. The plant is no longer comprised of isolated cells of activity. Each side knows what the other is doing at all times and can quickly adjust to change.

Information must also be able to flow from the plant floor to business-level systems (a.k.a. vertical integration). The main goal of vertical integration is to increase productivity and customer service by gathering information in real time. That means, for example, an operator with access to a PC can sit in an office and check the general operation of any given line to make sure it is at peak productivity. On-the-spot access to this type of information equals an unlimited resource for knowledge. And this knowledge can be synthesized into process improvements: "We need to adjust batch sizes to make sure the packaging lines are constantly running."

Using a mix of dedicated and open systems hardware, software, and networking technologies, Integrated Architecture gives engineers the means to gather and share data both horizontally and vertically. This provides the knowledge to drive out inefficiencies that plague production. It also lowers long-term costs associated with training, configuration and maintenance, and improves operational excellence and efficiency. The primary benefit, however, is a cohesive facility with the ability to manufacture, package, and ship more goods.

This same level of flexibility applies to SERCOS networks as well. For the critical task of integrating high speed motion feedback across multiple servo drives, SERCOS offers a reliable, fiber-optic interface. ControlLogix SERCOS support is a key element to enabling the maximum number of servo axes needed for an application responding in the minimum possible time. Sercos connectivity is also critical in reducing the wiring and commissioning costs of multiaxis systems as its fiber-optic communications ring replaces a host of encoder feedback wiring from drives to controller. This is unquestionably one of the most trouble prone elements of a high speed machine as well and the reduction in downtime associated with these problems is dramatic.

Developing a motion-control system is an easy four-step process with the Logix platform.