The manufacturing environment today is as challenging as it has ever been. Customers demand high degrees of customization and flexibility. At the same time, lean operating principles have slashed the level of in-house engineering talent at machine builders and manufacturers, alike. In this environment, engineering and maintenance departments seek the most efficient way to design, build, and maintain platforms and products.
The days of dedicated manufacturing lines churning out a single product 24/7 are gone. End-users want to change package sizes, alter product form factors, and do it all in minutes rather than hours or days. OEMs want to create machine platforms that can be tailored for specific applications with minimal effort.
Software-based control of electromechanical systems provides an effective approach to building and packaging many different kinds of products with the same machine. Hardware investment is minimal – software does the work. The problem is how to develop and update the code without major investments in software development. The solution is function block programming. The function block approach to controls provides an essential tool to help OEMs and end-users alike get better product to market faster.
The evolution of machine design from mechanical to electromechanical systems is dominated by programmable logic controllers (PLCs) which are generally the foundation around which machinery can be developed. PLCs excel at tasks like timing, counting, and managing I/O. For many years, however, more sophisticated tasks like calculating motion trajectories and closing the loop on speed or position required a dedicated motion controller that had to be integrated with the PLC. This added cost, complexity, and size. Modern PLCs feature greater processing power and large amounts of memory. As a result, they can take on many types of motion tasks.
It’s a good concept but the devil lies in the details. Disciplines like motion and feedback such as machine vision require engineers to learn and implement yet another collection of semi complementary programming languages. The push for flexibility adds yet another level of complexity. The code running a rotary knife is quite a bit different from that for a flying shear, for example. The cam profile for a form-fill-seal machine for a 10-inch potato chip bag differs significantly from that out for a 12-inch bag. In addition, the visualization screens for the human machine interface (HMI) need to be developed so that operators can easily switch from one operating mode to the next without having to access the software. The tasks for the design team
become more and more complex and time-consuming. In a move to streamline the development process, the industry developed the International Electrotechnical Committee 61131 (IEC 61131) standard for programmable logic controllers (PLCs).
IEC 61131 is a framework for standardizing PLC programming. In particular, it outlines the concept of reusable function blocks. The standard defines function blocks for specialized control functions. A function block incorporates both algorithms and data, as well as interfaces to ensure interoperability. IEC 61131 gives users the choice of four different languages, including Instruction List, Structured Text, Ladder Diagram, and Function-Block Diagram. Although IEC 61131 significantly streamline the process of programming PLCs, it is not necessarily easy to implement. The standard gives general guidelines but leaves plenty of room for differentiation. As a result, building function blocks still requires deep software development expertise. This led to the launch of PLCopen.
PLCopen is an industry association built around IEC 61131-3, the programming module of the IEC 61131 standard. The goal is to minimize the cost of machine development and maintenance. Members work together to create specifications and standardized function block libraries targeting different applications. Because it is an open-source organization, function blocks are available for reuse.
PLCopen function blocks simplify PLC programming. They still require a certain level of expertise, however. Customizing a function block for a specific application takes time and effort, particularly when the PLC needs to handle tasks like motion control and visualization. Making modifications, for example to change product parameters, requires the OEM or end-user to go into the function block and alter the code. Any time that is modified, there is opportunity to introduce errors. Ensuring accuracy requires debugging and validation, which increases development time and cost.
The function block approach dramatically streamlines PLC programming and customization of machinery. It is a major improvement over developing PLC code completely from scratch, particularly for complex systems. Reusable function block libraries also can be helpful but companies should remember that considerable engineering effort may still be involved to tailor the code to the machine and the application. Organizations still need to ensure they have a minimum level of software expertise in order to ensure performance and minimize error.
iQ-Monozukuri packaging speeds development of packaging lines
Named after the Japanese word for manufacturing, iQ-Monozukuri Packaging is a preconfigured engineering tool created to simplify the design, commissioning, and maintenance of packaging machinery. It features a complete library of packaging-specific function blocks, sample programs, and HMI sample screens for specific applications. The result is a platform that minimizes programming hours and speeds time to market.
The release of IEC 61131 and PLCopen may have improved the process of software development but working with function blocks still requires a significant level of customization and expertise. iQ-Monozukuri Packaging eliminates those headaches. With iQ-Monozukuri Packaging, OEMs can easily create projects based on cam profile function blocks, software templates, and Graphical Operator Terminal (GOT) templates included in the package.
The function block library is written and verified by Mitsubishi Electric engineers. Function blocks are applicable for:
- Rotary cutters
- Flying shear
- Box motion
- Long dwell times
- Mark detection
Instead of writing or customizing function blocks, machine builders and end-users just need to enter parameters on a screen. Creating cam profiles requires minimum cam knowledge and no cam calculations. Different types of packaging machines can share a single programming template. This enables OEMs to adapt the sample programs to different types of machines much more quickly than if they were developing their own code from scratch. Perhaps most important, iQ-Monozukuri Packaging makes it possible to boost production throughput by creating efficient programs for fast processing. Highly synchronized motion control delivers accurate and consistent operation implemented with simple motion modules.
Find out how iQ-Monozukuri Packaging can reduce engineering hours on your next
project, freeing your team to innovate.