Relevant Standards; Safety Concept; Safe Incremental Encoder Function; Safe Absolute Encoder Function - Kübler Sendix 5814FS2 Manual De Instrucciones

internal diagnostics do not allow the encoder to trigger on its
own initiative actions such as initiating a safe state, it belongs
to the Acquisition / Sensor category in the safety function
Information about "functional safety"
The encoders described in this manual are, depending on the
variant selected, suitable for use in safety-oriented systems
up to SIL2 or SIL3 according to EN 61800-5-2 and up to PLd
or PLe according to EN ISO 13849-1, in conjunction with con-
trols or evaluation units that have the necessary diagnostic
function DC=90 % or DC=99 %.

3.4.1 Relevant Standards

The safety assessment of the encoder is based on the follow-
ing standards and safety classes:
Relevant Safety Integrity Level (SIL) according to EN
Standards 61800-5-2
Performance Level (PL) according to EN
ISO 13849-1
BA Sendix® 58xxFS2 / 58xxFS3 - R60049.0009 - 03
NOTICE

3.4.2 Safety Concept

3.4.2.1 Safe Incremental Encoder Function

To obtain safe incremental information with the encoder, the
encoder evaluation unit must check the validity of the analog
signals. For a speed determination with the correct algebraic
sign, as well as for correct incremental information, both the
sine signal and the cosine signal must be evaluated, e.g. us-
ing the function sin²(x) + cos²(x) = 1 and quadrant monitoring
of the resulting unit circle, e.g. by means of permanent speed
monitoring.

3.4.2.2 Safe Absolute Encoder Function

To obtain safe incremental information on the absolute posi-
tion with the encoder, the encoder evaluation unit must count
the incremental pulses (relative position) and compare the
result with the absolute position also provided by the
encoder. The digital absolute information alone is not safety-
oriented.
The comparison of the digital position data with the sine and
cosine signals allows continuously checking the reported pos-
ition and detecting a deviation of the two signals. Since this
function requires both the incremental information and the ro-
tation direction information for the check, the achievable
safety level is limited to this.
Before switching the facility off, the absolute position value
must be saved by the encoder evaluation unit. When switch-
ing it back on, the encoder evaluation unit must compare the
saved value with the absolute value newly measured after
EN - 39