Dual SiGNUM™ Interface

Precision rotary axes often demand very high accuracy without calibration or error-map compensation. As a modular solution, DSi allows a second readhead to be added, which eliminates odd error harmonics including eccentricity and compensates for the effect of bearing wander. The result is total installed error of typically ±2.5 arc second (200 mm diameter RESM). For ultimate precision, DSi combined with the new ultra-high accuracy REXM ring offers better than ±1 arc second total installed accuracy.

DSi provides the customer located and angularly repeatable propoZ™ reference (index) position, which is completely unaffected by bearing wander or power cycling. The desired propoZ™ index position is selected by driving the axis to the chosen angle and simply pressing a button. This feature makes alignment of the encoder's reference position to the T-slots on a machine tool rotary table, for example, faster and more precise. The selected angle is then stored in the DSi's memory so the patented propoZ™ index is locked to that angle, ensuring perfect angular repeatability… even if the centre of rotation of the axis moves whilst the DSi is switched off.

DSi makes adding a second SR readhead very easy. By combining the incremental signals from the two readheads and using patented reference mark processing, the DSi appears to the controller as a single very high accuracy encoder.

Furthermore, DSi maintains the dynamic advantages of SiGNUM™ encoders. As a non-contact system, SIGNUM™ RESM rings are taper-locked to the rotor shaft, ensuring a compact axis design and the elimination of coupling losses, oscillation, shaft torsion and other hysteresis errors that plague enclosed encoders.

Like the rest of the SIGNUM™ encoder range, DSi is capable of operating at speeds up to 4,500 rev/min and temperatures up to 85°C. SIGNUM™ also benefits from rugged IP64 sealed readheads, dynamic signal processing for excellent reliability, and ultra-low cyclic error (±30 nm). In addition, comprehensive SiGNUM™ software enables optimum set-up and real-time diagnostics via a PC's USB port.

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