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Digitaler Sonnenschutz


									Standard Motor Interface
The idea of a continuously digitally controlled roller blind or sun screen is no longer merely a dream. Digital signal processing has become the standard technology for control systems in many other products. This new technology offers several striking advantages for roller blinds and sun screen drives. For decades, switch contacts have been used for controlling electrical drives. Now, a digital motor interface has been developed. The commands are digitally encoded and sent to the drive as a series of data frames. It is only practical to use digitally encoded commands when both sender and receiver can understand each other, that is, when they use the same codes. The SMI technical task force took on this challenge and developed the SMI specification. SMI stands for Standard Motor Interface. The specification describes a standardized electronic circuit and a standardized process for the communication of commands. This information interface is specialized for application in roller blinds and sun screen systems. Who will benefit from the new interface, and what are the applications? A digital controller offers several advantages, for producers of roller blinds and sun screens, and manufacturers of control systems, as well as for builders and users. Exact positioning The capacity to provide a more precise and constant positioning of the sun screen is an outstanding feature of SMI drives. The desired position is encoded digitally as a number and sent to the drive, which adjusts the blind exactly using an internal controller. This active principle ensures precision for the entire life of the drive. Wear and tear have no effect on the precision. Where is such a high degree of positioning precision necessary? For fine adjustment of the sun screen system in accordance with the position of the sun, for example, or when several sun screen systems are to be exactly coordinated for an entire facade, a high degree of precision is required. The advantages of digital command encoding may be easily seen in the following example: the driving axle is to be turned at a specified angle. Such movements are used for example in turning the sun screen blinds in accordance with the position of the sun. For this task there is a command, STEP, which triggers a turn at a pre-defined angle via the SMI interface. This command is understood and implemented immediately by all SMI drives from all manufacturers. All the drives turn together at the same angle. There is no longer any dependence on the rotational speed. Commands such as these are especially suitable for the adjustment of sun screen systems in accordance with the position of the sun. A logical step for automated facility management Bus systems such as EIB or LON communicate by digitally encoded commands. With the standard motor interface SMI, the industry now has a solution for the continuous digital control of roller blinds and sun screen systems. The digitally encoded commands from the building control system no longer need to be translated into automatically timed switching signals. There is no loss of precision. The development of a standardized interface constitutes a great simplification for the control systems industry. With the SMI interface, SMI drives from different manufacturers can all be equally accessed.

Parallel developments in CDs and roller blind or Venitian blind drives with regards to digital signal processing

SMI drives are especially suitable for precise positioning of blinds A drive unit can also send feedback - a function which was never even a possibility with conventional drives. Feedback is a necessary element in the efficient operation of large sunshade systems. Defective drives can report problems automatically and can be detected at a distance by a control centre. Savings in costs, installation time and space requirements The Standard Motor Interface makes possible the parallel electrical connection of up to 16 drive units. An addressing system nevertheless allows each drive to be controlled individually. This characteristic makes it possible to develop completely new concepts for installation with less cost, faster installation times and, not least, a significant saving of space. Up until now, each drive had to accommodate its own control unit with its own motor connection. For the parallel connec-

tion of up to 16 drive units, there are excellently suitable modern flat cable systems, for example, which require no installation boxes for branch connections. Individual programming Electronic drives with SMI interfaces can be programmed individually. The digital interface can also be used to program the functioning of the drives. This new capability of intelligent drive units allows the system to accommodate the individual requirements of the manufacturers of various roller blinds and sun screens. A standard drive can thus be transformed into an individualized, clientspecific unit. Manufacturers use this feature to integrate drive units into their particular products. An impressive range of drives The first drive units with SMI interface were certified at the beginning of 2004. In the meantime there has arisen a wide range of drives from various manufacturers which all use the SMI interface. These drives have different characteristics of performance and function. However, they all have one feature in common: they all communicate with the same commands and the same codes - a huge advantage for the industry. The list of SMI drives may be found in the Internet under the address Customers who buy products with SMI interfaces expect them to be compatible with each other. The reliable communication of encoded commands through the SMI interface must be ensured. The SMI group has developed a procedure for certification and registration. The manufacturers themselves inspect their SMI products according to a test procedure and declare them to be in conformity with the SMI specification. Not until all requirements are met can the certificate be issued and the product registered in the Internet list." An SMI drive may be recognized by means of the SMI logo. Only certified and registered drives are allowed to carry the SMl logo. The parallel connection of SMI drives is even simpler with flat cable systems. The photo shows a flat cable with a branch connection for an SMI drive.

Otmar Stillhard dipl. Ing. FH SMI office Ofenbachstr. 14 CH-8266 Steckborn

Daylight management systems are attractive applications for precise SMI drives

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