New control platform with motion control for wafer handling
April 12, 2010 by Williamzian Robin
Software standards make the change of hardware platforms easier
Nowadays the choice of a suitable hardware platform for a machine control is not an ever lasting decision and change over time can be needed. There may be many different reasons for such a change in controller platform. Sometimes, economical considerations are decisive for instance to move from a PC-based controller platform to an embedded version: after a number of machines of the same series the machine becomes more a commodity and a customized embedded controller can be a more economical hardware solution for the future. Even though the first series have been realized with standard controllers, the long-term competitiveness requires a change of the hardware over time. Often there are functional and technical aspects that are decisive for a change of controller hardware: previous controller variants quickly reach their functional limits due to a change of the high level machine design or a different strategy of the machine modularization, new networking requirements or operational requirements of older controller products. Only the porting to a new platform prepares the ground for the desired machine design.
This probable change make it for the machine manufacturer very important to have an software application which is hardware independent and which flexibility supports the hardware change. For the control supplier it should be part of the customer orientation to supply its products with standardized programming tools.
New control concepts – fit for change
As a partner of mechanical engineering who recognizes and implements trends at an early stage, ECKELMANN AG operates in all controller solutions (CNC, PLC, motion control) with different hardware platforms that have been developed and manufactured by ECKELMANN AG: PC-based, standard embedded controllers as well as completely customized hardware. Own software libraries are available for the three field of application CNC, PLC and motion control which can be used in an identical way on all mentioned hardware systems.
The typical controller functions of the three software libraries CNC, PLC and motion control can be called by the user in the form of function blocks which are part of the IEC 61131-3 programming tool CoDeSys. The support of such a software standard offers a variety of advantages to programmers and end users who mainly benefit from the broad testing and quick further development of these programming standards. Within the meaning of the above-mentioned strategy of a platform-independent controller concept, the use of a standard such as CoDeSys, moreover, creates the ideal pre-requisites for all types of program porting or for system change with simultaneous maintaining of the application software. Software standards offer safety and protect valuable investments made for the preparation of applications.
Application example: Tec-Sem switches over to embedded controllers for the wafer stocker Pr@ctor
Tec-Sem, Tägerwilen , Switzerland is established both as leading manufacturer of systems for the semiconductor industry and as supplier of OEM automation solutions for semiconductor tools. In particular, Tec-Sem is marketing products for wafer management without using cassettes. In 2005, the product series Pr@ctor was put on the market as a new, particularly flexible system. Pr@ctor is a system which combines the functions of stocking and sorting of 300 mm wafers in one tool – in addition measuring systems can be integrated.
The wafers are delivered via two to four load ports. The wafer ID is read in the handling and verification unit by means of a high-speed standard robot and a special aligner and the stocking in the connected storage towers is prepared via a buffer. The quick stocking without cassettes is designed mainly for highly complex applications with mixed, small production lots, increase requirements on cleanrooms and a high number of different wafer qualities.
Fig. 1: Tec-Sem wafer stocker Pr@ctor
Besides the robot and the aligner of the handling unit, in particular the handling axes and the lifting drives of the cassette-free storage towers are to be controlled in this machine. While the first models of the Pr@ctor series were equipped with PC controllers, very soon embedded controller solutions have been searched for reasons of modularization. The choice fell on the ExC55 controller of ECKELMANN AG. Equipped with the software module library „Motion“, this embedded controller forms the complete controller EMC55 for motion control applications of 2 up to 64 axes.
Fig. 2: Latest embedded controller of ECKELMANN AG
The motion control function blocks of the EMC55 are in compliance with PLCopen and the programming standard IEC 61131-3. Based on this Tec-Sem is able to port the available controller software at a ratio of 1:1 to the new hardware platform. An additional advantage as far as compatibility is concerned is the controlling of the drives via the standard CANopen interface as per DS402 (interpolated position mode).
In fact, this change of system can be realized so smoothly that the change-over could be carried out at the sole responsibility of the machine manufacturer. Additional programming expenditures or parameterizing did not incur. Sometimes it is very easy to find a new home for a proven machine controller.
Fig.3 : Splash screen of the Pr@ctor user interface