SI25101B_e.DOC / Mrz-08
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1.
Introduction
SI251 represents an encoder interface unit, designed to convert output signals of so-called
“sine-cosine-encoders” and similar measuring systems into incremental quadrature impulse
signals.
Under consideration of an adjustable multiplier the unit interpolates a corresponding number of
impulses from every sine wave. An additional programmable divider provides division of the
impulses if applicable, before they appear at the output. Impulses are available with TTL/RS422
standard (A, /A, B, /B, Z, /Z) and with HTL standard (A, B, Z, 18-30V) at the same time.
SI251 also possesses a selectable glitch filter to minimize interferences on the signal lines. The
maximum sine input frequency is 400 kHz. The interpolation rate can be set in a range from 5 to
50, i.e. the unit can generate up to 50 pulses from one sine period
The maximum output frequency is 4 MHz with use of the RS422 output, and approx. 100 kHz
when the HTL output is used. Where applicable, the output frequency can be reduced by a
selectable divider 1:1 – 1:128.
Independent of the selected interpolation rate, an interpolation time can be set in order to limit
the output frequency to a desired maximum value.
The unit provides auxiliary output voltages of 5.2 volts and approx. 20 volts, all short-circuit-
proofed, for power supply of the sine/cosine encoder.
Errors will be signaled by a LED and at the same time by a digital control output. Errors can be
reset by means of a pushbutton on the unit, or by a remote reset signal.
All settings are done by means of two DIL switches which are accessible from the top site and
the bottom site of the housing.
The mechanical construction provides a compact housing for rail mounting, with
12 screw terminals and two Sub-D-connectors
