Fig. 11 Safety-Related Block Diagram With Subsystems - Pilz Intern PMC SR6 Manual

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Each component of a safety function is part of a specific permanent structure. This is referred to as
the category in EN ISO 13849-1. The categories form the basis for the calculation of the resulting
safety figures, e.g. in the SISTEMA software. In this process, a subsystem represents either a group
of category blocks or a safety component with manufacturer information on PL, category, PFH, etc.
(= encapsulated subsystem).
Subsystem SB1
Fig. 11: Safety-related block diagram with subsystems
SB1 – SB3
B1, B2
K1
T1
The protective device with the position switches forms subsystem 1, the safety relay forms subsystem
2, the drive controller along with integrated PMC SR6 safety module is represented by subsystem 3.
Design features
Fundamental, established safety principles such as the requirements for the controller structure of
category B are observed; protective wiring systems (e.g. contact fuse protection, grounding for the
control circuit) are provided.
Cross circuits and short circuits in electrical connection lines are to be taken into account during
planning according to DIN EN ISO 13849-2, Table D.4. Errors that arise must be detected and
brought to a safe state. Alternatively, the lines can be routed in such a way as to exclude any possible
short circuits or cross circuits.
The starting mechanism must be properly designed and installed for the electromechanical position
switches B1 and B2. Actuation elements and position switches are to be protected from position
changes. Only rigid mechanical parts may be used (no spring elements). The position switch B1 is an
established component in accordance with DIN EN ISO 13849-2, Table D.3 with a positively driven
contact in accordance with DIN EN 60947-5-1, Appendix K.
The safety relay fulfills the requirements of category 4 and PL e.
T1 indicates a drive controller with integrated STO safety function. The requirements of category 4
and PL e are met.
Manual PMC SR6 safety module
1005344-en-US-01
Intern
Subsystem SB2
B1
K1
B2
Input Logic
(Encapsulated) subsystems 1 – 3
Position switches
Safety relay
Drive controller with integrated PMC SR6 safety module
Subsystem SB3
STO
a
T1
STO
b
Output
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