SIEMENS
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Siemens PM 21 · 2017
Safety Integrated
Overview
5
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Function
(continued)
Safe speed/position sensing
Incremental encoders or absolute encoders can be used for
safe sensing of the position values on a drive.
Safe actual value sensing relies on the redundant evaluation of
the incremental channels A/B that supply sin/cos signals with
1 V
pp.
Only encoders of the type whose A/B track signals are
created and processed using purely analog techniques can be
used.
HTL/TTL incremental encoders may also be used. In this case,
safe actual value sensing is achieved by using two independent
encoders. The minimum possible speed resolution must also be
taken into account.
The encoder signals are read via Sensor Modules.
For information on the Sensor Modules, see the Industry Mall un-
der Drive Technology/Converters/AC Low-voltage converters/
High performance converters SINAMICS S/SINAMICS S120
built-in units/Supplementary system components/Encoder sys-
tem connection or the Catalog D 21.4 SINAMICS S120 and
SIMOTICS – Motion Control Drives.
As an alternative, motors with an integrated DRIVE-CLiQ inter-
face can be used. The speed or position actual values are
generated directly in the motor as safe values and are made
available to the Control Unit over safe communication via
DRIVE-CLiQ.
Certified built-on rotary encoders with DRIVE-CLiQ interface
may also be used (see
).
The encoder must be mechanically attached in such a manner
that the encoder shaft is unable to unplug or slide off. For notes
on this, see IEC 61800-5-2: 2007, Table D.16.
A list of Siemens motors that fulfill the electrical and mechanical
requirements is available at:
The following can be used for safe speed/position sensing:
•
Single-encoder systems or
•
Dual-encoder systems
Single-encoder system
Example: Single-encoder system
In a single-encoder system, the motor encoder is used exclu-
sively for safe actual value sensing.
Dual-encoder system
Example: Dual-encoder system on a spindle
In the case of the dual-encoder system, the safe actual values
for a drive are provided by two separate encoders. The actual
values are transferred to the Control Unit over DRIVE-CLiQ.
When motors without a DRIVE-CLiQ connection are used, a
Sensor Module must be provided.
HTL/TTL incremental encoders can be used as an alternative
with a dual-encoder system. Either two HTL/TTL encoders, one
dual-HTL/TTL encoder or one HTL/TTL encoder and one sin/cos
encoder can be used.
Safe actual value sensing without encoder
The Extended Functions Safe Stop 1 (SS1) with SAM/SBR, Safely
Limited Speed (SLS), Safe Speed Monitor (SSM) and Safe Direc-
tion (SDI) are also available for use without encoders (only in
combination with asynchronous (induction) motors and
SIEMOSYN motors).
An encoder that is used for the purposes of motor control has no
significance for the safety function here.
Note:
The Safety Integrated Extended Functions "without encoder"
must not be used if the motor can be accelerated by the load,
e.g. if a vertical axis is under a load due to gravity.
The Safety Integrated Function Manual contains additional
information about the encoderless safety functions.
E = Encoder
M = Motor
Sensor Module
(not applicable for motor with
DRIVE-CLiQ interface)
Backlash
Machine table
G_D211_EN_00216b
DRIVE-CLiQ
E
M
E = Encoder
M = Motor
Sensor Module
(not applicable for motor with
DRIVE-CLiQ interface)
G_D211_EN_00217b
DRIVE-CLiQ
E
M
E
© Siemens AG 2017