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Made for motion control
By Roy OConnor, European Bureau Chief, Global Design News -- Design News, March 24, 2002
Nuremberg, Germany — Although already covering a large number of applications with its Simatic range of programmable logic controllers (PLCs) and the high-end Sinumerik machine controller, Siemens Automation & Drives has introduced a mid-range controller specifically for motion control duties. The Simotion controller, as it is known, is intended for tasks too complex for the Simatic, but where the specification of the task hardly justifies moving up to a Sinumerik. Because Simotion involves the integration of the drive and controller, it enables complex motion control and simple motion-related PLC functions to be implemented on the same system. Time-critical interfaces between components are eliminated, along with the programming and diagnostic effort they involve. In addition, programming and diagnosis of the entire system is easier and more transparent.
An engineering system, the Simotion Scout (which runs under Windows on commercially available PCs), a runtime system, and the actual hardware platforms comprise the Simotion system. Project planners use Simotion Scout to define the motion control tasks and related control functions. This includes the sequence chart for project planning, selected technological functions, and associated user programs. All tools integrated in the Scout have the same look and feel. Depending on requirements, Simotion Scout can be used as a stand-alone system or integrated into the Simatic Step 7 system.
Three different hardware platforms can run all functions and the software system. These are the controller Simotion C, the industrial PC Simotion P, and the drive-based version Simotion D. While the industrial PC version is intended for applications demanding openness and flexibility, Helmut Gierse, president of Siemens A&D, sees the drive version as giving the greatest potential. Commenting on flexibility, he adds, "Once designed, a Simotion solution will run on a PC, a controller, or a drive platform."
Basic functionality represents the lowest interface for the user, providing instructions for tasks such as motion control functions, timers, and input/output access. Technological packages then extend this basic functionality. For example, the Position package provides all the functions for precise positioning, the cyclical exchange of set points, and actual values with drive, referencing, status information, etc. Gear and Cam packages are provided for gear and cam disk synchronization, and other packages allowing for pressure and temperature control are planned. According to Georg Trummer, head of development for production machines at Siemens A&D, "The Simotion system enables machine builders to design their own technologies using their own expertise." They will also be able to develop their own technology packages using a special C/C++ development kit.
Function libraries enhance the range of uses. These include PLCopen for motion control, and standard applications such as winders and on-the-fly cutters. Some of these modules can be obtained as source code. The IEC 1131-3 programming interface gives the user programming access to all of the system functions—basic functions, technological packages, and function libraries. Trummer says this multi-layer architecture makes Simotion scalable in its number of functions, flexible with its technology packages and libraries, and extendable through additional modules.
For more information about Simotion from Siemens A&D: Enter 494
