The CSi mechanical engineering company of Raamsdonksveer, the Netherlands, supplies palletizers constructed in accordance with a modular concept. Their 'Machine Control Concept' integrates soft PLCs and PROFIBUS with mechanics, hardware and software in the manufacture of customized mechatronics products. Nowadays a maximum flexibility is the primary requirement imposed by large-scale users of production systems ? a condition which is imposed as a result of the increasingly shorter life of products and their packaging.
CSi's approach is a good example of the continually increasing integration of industrial automation. Mark van de Klundert explains: "For us integration involves the combination of the Visual Basic software, the IEC 61131 software, the Twincat Soft PLC platform, the IPC hardware, the standard control cabinet, the standard plug and play cabling in the bus, and the complete mechanics into one system." It will be self-evident that all I/Os make use of PROFIBUS, as a result of which cabling is reduced to a minimum. The plug-and-play system enables the production staff to assemble the installation without the assistance of electricians. All sensors and actuators are connected with plugs. "We achieve our time savings by virtue of the fact that everything is right first time; in the absence of terminal banks it is impossible to make an incorrect connection", according to Mark van de Klundert. The safety controls are also incorporated in the control concept in accordance with category 3.
The use of soft PLCs in an industrial PC offers virtually unlimited space for the program and the data. Moreover the response time of a soft PLC is much shorter than that of an 'ordinary' PLC ? and the cycle time is always of the same length. According to Industrial Automation Link, in Haarlem, this is one of the great benefits offered by a soft PLC such as TwinCat. TwinCat works with real-time multi-tasking. A conventional PLC scans all the I/Os in each cycle and, depending, on the load, adjusts the cycle time. The cycle time can steadily increase ? and certainly in the event that the PLC is communicating at the time; this increase is detrimental to the machine functions.
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