20 April 2010
Unlike other production plants, filling and packaging plants are now generally not controlled from one central point. Many control panels on individual machines and conveyor systems look after the material flow throughout the plant. The drawback to this approach is that individual machines cannot always be reached directly in the event that operator intervention is required or problems arise. It is also not always possible to man every station with an operator, since this results in excessive time and expense. In order to remain competitive and to manage the plant more efficiently, an operator must have an overview of every operator station, must have the ability to intervene rapidly in the production process where necessary, and must have the ability to detect problems and respond immediately. Krones AG, a company specialising in installing and configuring complete filling and packaging lines, says that information flow has today become every bit as important as material flow. This company, based in Neutraubling in Bavaria, is specialised in installing state-of-the-art network technology and software. Krones has already set up countless filling and packaging lines for glass bottles, PET containers and cans on behalf of breweries, soft drink manufacturers and companies involved with the wine and spirits industries.Network technology underpins further developmentManufacturer-specific bus systems have so far been the most commonly used means of connecting individual machines with a system for the purpose of sending and receiving information. Industrial Ethernet has now emerged as the best medium for transferring large volumes of data between IPC devices.Krones uses fibre-optic cables here, thus avoiding electromagnetic interference. Krones installations are also unaffected by any limitation on the length of fibre-optic cables, since cables within the plant will never exceed the maximum permitted length of 2km. When a network is implemented with copper cable, on the other hand, the picture is quite different: data transfer can become unreliable as soon as cable lengths exceed 100 metres. The network structure favoured by Krones for its filling and packaging lines has a star configuration with a central network server. This guarantees the user maximum freedom from interference since the connections in the network are exclusive. Furthermore, every single machine can avail itself of a 100 Mbit/s bandwidth, and all applications – including the line diagnostics system, the line management system, the process control system and the mobile service information system – can run concurrently and without any form of mutual interference.Visualisation and efficient management of plantsWhen it comes to human machine interfaces Krones uses zenon from Copa-Data for its machines. Zenon software features a drag and drop interface for networking individual machines to form an integrated system. A separate machine (known as a “stand-alone project”) is activated with a click of the mouse and converted into a network project when the user drags it to the desired position in the zenon network manager’s project tree. If the user enters the corresponding computer name or selects a computer, then the desired operator terminals will become available. An intelligent token ensures that all operator actions are managed. If an authorised user submits a request, then the token is passed to that user in order to avoid actions being duplicated and errors occurring. The project manager can define in advance which functions zenon is allowed to perform on the network, and which are not permitted. Furthermore, zenon does not require a central server. Any control panel that is assigned to a controller can act as a server for another client – an operator terminal, for instance. In this way, data is transferred between the terminals and projects are also harmonised as soon as any changes are carried out on a project. There is no need for any additional server hardware since the system has a distributed configuration and can thus operate on a Compact Flash-card basis. Maintenance can be carried out remotely on the HMI as well as the PLC systems. The basic philosophy behind the networked visualisation is that operators can perform whatever actions are required at any time and from anywhere in the plant. Such actions include configuring systems, changing types, switching on units and, if necessary, retrieving alarms and trend data.
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