SFA: the all-in-one absolute wire actuated encoder Absolute, compact, reliable: SFA cable pulling encoder is the simple and inexpensive measuring system built to provide linear position information in your any industrial applications, especially where space is constricted SFA is the latest model of Lika Electronic draw-wire series and follows the showcasing of the new 2012 models: the entry-level SFP stringpot; the SFE incremental version; the universal and versatile SF-x model which allows the wire mechanism (up to 6800 mm / 267.7” measuring length) to be paired with whatever encoder is best suited to your needs: incremental (NPN, PNP, PushPull, Line Driver, Universal, 1Vpp), absolute (SSI, BiSS), fieldbus interface (CANopen, Profibus, D e v i c e N e t , EtherCAT, Modbus), programmable (SSI, bit parallel, analogue current/voltage), ATEX (CANopen, Profibus). SFA model is the all-in-one wire actuated absolute encoder. It fully integrates in a single package both the cable pull assembly and the absolute multi-turn encoder. This results in a very small, compact and robust device ideally suited for a variety of industrial applications, especially for installation where space is limited. The working principle in fact allows the wire to provide safe linear position feedback even in constricted or inaccessible environments, while the sensing circuitry can be kept protected from external influences and contaminants.
The cable is in tough stainless steel, is offered in 1000 mm (39.37”) and 2000 mm (78.74”) measuring length versions and can operate at a maximum speed of 1 m/sec. The stroke per revolution is 100 mm / 3.94” in both cases while the maximum number of revolutions is 10 for SFA-1000 model and 20 for SFA2000 model. Precise linear guidance is not required and the wire flexibili-
ty allows for almost linear and even curved position measurements. The wire can be fastened easily and inexpensively to the moving equipment just using the provided nuts and no further component is required. SFA cable pulling unit integrates a well-proven absolute multi-turn encoder with non-contact magnetic scanning. It offers up to 8192 information per revolution (i.e. 81,92 information per millimetre); anyway it is also available with a clear exact correspondence between number of information and metric
measuring length: for instance, 2000 information per revolution, i.e. 20 information per millimetre. It boasts a notable resolution ranging between 0,1 and 0,012 mm (i.e. between 100 and 12 µm!). The absolute position information is provided via 25-bit LSB right aligned SSI interface in either Binary or Gray code. Both cable and M12 connector options are available. The encoder implements the zero setting function and the reverse polarity protection. SFA cable pulling encoder is suitable for installation in a variety of industrial applications for both linear position and speed measurements. It finds typical use for short travel distances in telescopic systems and hydraulic pistons (for instance in mobile equipment such as outriggers, stabilizing slides, telescopic cranes, booms ...), forklifts, man-lifts, scissor lifts and loading platforms, printing and measuring machines, store and convey systems, medical technology applications such as examination tables, X-ray machines, dentist's chairs and laboratory testing devices, and many others.