OPL Solution Enables Cost Benefits in Packaging
Opinion Article – Feature
OPL Solution Enables Cost Benefits in Packaging
Siemens supports packaging industry initiatives in standardization with the Optimized Packaging Line
At the last PackExpo, one exhibit demonstrated a concept that for many years had been an unfulfilled vision in the minds of those responsible for packaging lines. The exhibit consisted of a packaging line section made up of four machines, all from different manufacturers yet all communicating and synchronizing together.
A key element of the exhibit was a handling unit equipped with an automation and drive solution from Siemens. The solution is part of Siemens’ Optimized Packaging Line (OPL) concept, a program developed to support the packaging industry and its need for standardization in the control systems for packaging machines. The positive response of visitors to the exhibit reflects the strong desire for standardization in the industry. Many visitors were impressed with the OPL concept and commented that it looked quite simple to standardize using Siemens equipment and the OPL approach.
Efforts to standardize packaging line systems go back to the late 1980s when the International Society of Automation (ISA) began to develop a set of standards for the batch control industry. A standard set of models and procedures, ISA-S88 Part 5 (Make2Pack), was written to provide a standard, specifically for equipment modules and control modules. This work was further developed by the Organization for Machine Automation and Control (OMAC). The OMAC Packaging Workgroup used the ISA-88 state model concepts to develop "line type" definitions known as PackML.
For communication between machines, OMAC developed the PackTags standard, which is a comprehensive set of naming convention guidelines for communication between production machinery and support systems such as the human-machine interface (HMI) or manufacturing execution system (MES). PackML and PackTags, together with industry communication standards, enable a plug-and-play approach to assembling different manufacturers’ machines in a packaging line. All systems are implemented using a common set-up, which greatly simplifies integration.
Dr. Bryan Griffen, chairman of the OMAC Packaging Workgroup and global head of electrical and automation engineering for Nestlé Corporate Engineering, is a PackML expert. In a presentation at the Automation Conference in Chicago, Griffen showed 13 different HMI screens on a single packaging line, with absolutely no common look or feel, reflecting the differences in software between the machines and the need for HMI standardization. Griffen then explained how PackML addresses these issues: "PackML defines a machine’s state – holding, running, executing, stopping, aborting – and it makes that consistent from machine to machine. It also defines machines’ modes – maintenance, jog, cleanout, operating, et cetera. Together with PackTags it standardizes the way data are moved outside the machine. The PackTags carry information about the condition of the machine in a very specific format that lets the machine next to it pick up that info and know what it means."
Siemens’ contribution to standardization
Siemens has long been a supporter of machine standardization in the food and beverage industry. As a member of the OMAC initiative, Siemens was a major contributor to the multivendor prototype demonstrator exhibited by OMAC at PackExpo. Four machines made up the demonstrator. Siemens equipped the handling unit, with three other OEMs providing the rest of the machines. All the machines executed their operations under PackML programs and communicated via Industrial Ethernet utilizing the Weihenstephan protocol.
In preparation for PackExpo, the Nestlé Product Technology Center (PTC) Automation in Orbe, Switzerland, invited four automation technology vendors to discuss and develop a prototype for future machine and lines and specify suitable concepts. Siemens was part of this process and supported the project with modules from its own OPL concept. To verify the concepts of the PTC, the team set up a demonstration plant. One essential element has been the implementation of the application based on the OMAC state model and the mode manager. The definition of the serial interface between the line HMI and the machine model (vertical communication) is based on OLE for Process Control (OPC), and the data exchange between the machines in the line using the Weihenstephan protocol (horizontal communication) is based on OMAC PackTags. The implementation of the Siemens application was smooth, since all the functions already existed as modules in the OPL concept and the existing libraries could be used. Following this project, Siemens can also provide a customized, OEM-certified module library for future specifications at Nestlé.
The result was showcased at the last PackExpo: The prototype line demonstrated the successful use of an international standard solution (OMAC PackML) for synchronizing equipment without the need for a line PLC and showed that machines from different OEMs can communicate on the same network and protocol. The reception of the prototype was remarkable, and especially the handling unit running Siemens’ standard OPL software caught the attention of many visitors because of the simplicity of the systems in this machine.
Greater transparency and line efficiency
When automation was first introduced, packaging lines were frequently constructed using machines from many different manufacturers. This was because manufacturers had different strengths and areas of expertise, and the line designer wished to use the best machine for the job for each operation. This often led to difficulties in the control and monitoring of the line because of a lack of standardization in the programming of the various machines. The lack of software consistency between machines made horizontal and vertical integration difficult and time consuming, and problems were hard to troubleshoot. The many different HMIs created training challenges for both operators and technicians.
In its participation in industry organizations such as OMAC and in talking directly with leading companies in the food, beverage, consumer goods and pharmaceutical industries, Siemens received a clear message: a standard approach is needed for the control of packaging lines. Siemens is actively involved in a number of industry groups working toward this goal.
Packaging line integrators want tighter line integration, better data visibility and reduced lifecycle costs. In response, Siemens developed the OPL concept, a system fully compliant with industry standards such as PackML and PackTags yet simple to implement and without the burden of compromise. With OPL, Siemens addresses many of the issues identified by the OMAC Packaging Workgroup. Based on Totally Integrated Automation, Siemens’ open system architecture for seamless automation, OPL integrates the complete packaging line based on a standard automation and communication platform.
OPL consists of a set of standard modular hardware and software products designed to integrate together in a seamless platform, with all machines and systems working together as one. Each machine has a well-defined standard interface that enables it to connect to a line-wide information network. The easy networking and communication mean that data from all machines can be consolidated into higher-level monitoring and management systems.
OPL implements international standards such as Weihenstephan (a universal communication interface for the vertical integration of machines encompassing the communication protocol and mode and state manager for the machines) and Profinet. It fulfills the international directives for open and modular automation architectures defined by the OMAC User Organization. The parameters for communication via Profibus and Profinet are defined up to the plant-wide level, with clearly specified interfaces for messages and alarms.
OPL provides a standard operating concept for diagnostics, with line components uniquely identified and a complete overview of the state of each machine available at a mouse click. The information flow is seamlessly integrated to support a wide range of scalable tools – for example, for line visualization, key performance indicator reporting, power management, and so on. The range of tools can be flexibly adapted on a customer-by-customer basis and can be expanded from basic functions up to a complete MES infrastructure.
OPL Software Toolbox improves engineering efficiency
To facilitate the machine engineering process, Siemens provides a software toolbox as part of the OPL offering, comprising open tools for implementing packaging applications using standardized yet customizable software modules and function blocks. The OPL Software Toolbox makes it easy to create a uniform and modular software structure for the various machines in a packaging line.
The OPL Software Toolbox libraries cover all the essential functions, including system test, alarms and reporting. Machine and state control follows OMAC and Weihenstephan standards, including the matching interfaces for easy line integration of machines. Technology modules in the OPL Software Toolbox are built in accordance with the Make2Pack ISA-88 hierarchy, providing a uniform interface to a complete set of equipment and control modules.
The OPL Software Toolbox project generator can automatically create a Weihenstephan standard-compliant data interface for Simotion motion control systems and Simatic controllers.
The benefits: software engineering is faster, simpler and more efficient, and the software itself has a modular structure for easy customizing and modification, supporting modular machine concepts in packaging.
The next logical step
The standardization provided by OPL greatly speeds up software engineering and provides an enormous benefit to commissioning and service staff, as every machine uses the same software modules. The consistent HMI templates generated by OPL for each machine dramatically reduce the training burden. Operators can easily migrate from machine to machine, and the problems caused by machines being operated by less-qualified staff are mitigated. This alleviates the management issues associated with running a line round the clock and resolves the HMI usability issues being discussed in the OMAC Packaging Workgroup.
The OMAC Packaging Workgroup’s Griffen says, "The next logical step will be that end user specifications will no longer define a vendor for the automation systems but will require the machine to be built according to PackML/PackTag standards." If and when this happens, the OEM machine builder will no longer be required to use a specified brand of controller or drive for a certain task but will be able to choose the most appropriate component for the task. This should allow the OEM to focus on its core expertise of machine design and differentiate itself through the features supplied by the mechanical and servo drives.
Through its OPL concept and services, Siemens will continue to support machine builders in implementing packaging standards to help reduce both development and commissioning times and costs. With OPL, the line operator benefits from a consistent system architecture and seamless data integration supporting operation, diagnostics, and maintenance – increasing uptime and enhancing line productivity.
Advantages of standardization
The advantages of OPL as a standardization system are numerous. Start-up expenses are reduced due to lower integration costs and decreased complexity. Engineering costs are lower and installation and commissioning is faster. Operating expenses are lower due to fewer sources of faults and shorter downtimes. Staff costs are reduced due to lower training costs, and shopfloor operators are more flexible thanks to the common HMI across all machines.