Siemens SIRIUS 3RK3 Equipment Manual page 34

Overview
3.1 3RK3 Modular Safety System
3RK3 central unit with AS-i interface
The 3RK3 central units with AS-i interface also perform the functions of an AS-i safety monitor.
These central units can read in safety-related, standard, AB, and CTT2 data on the AS-i bus,
control safety-related outputs on the AS‑i bus, and simulate safety-related standard and AB
slaves. Diagnosis of the system is possible through the AS‑i using the CTT2 protocol. Data can be
passed to the controller cyclically/acyclically via AS-i or can be received from it. Safety-related
communication between two or more MSS 3RK3s is also possible via AS-Interface (direct data
exchange).
The following 3RK3 central units feature an AS-i interface:
• MSS 3RK3 Advanced
• MSS 3RK3 ASIsafe basic
• MSS 3RK3 ASIsafe extended
3RK3 expansion modules
The MSS 3RK3 central units can be optionally combined with 3RK32 and 3RK33 expansion
modules.
With the expansion modules, you increase the number of inputs and outputs of the MSS 3RK3
to suit your requirements. The quantity depends on the 3RK3 central unit and the number of
sensors and actuators evaluated.
Interface modules for communication via bus systems and integration in TIA
3RK3 central units communicate with higher-level controllers via an optional interface module.
In this way, the MSS 3RK3 can, for example, be interfaced to a PLC via PROFINET. Fault
diagnostics and status information can be passed on cyclically and acyclically.
Via the PROFINET interface, the MSS 3RK3 offers the possibility of exchanging process signals
with a higher-level controller. This is possible in both directions. Up to 64 bits are available for
this purpose in each direction. The individual signals are manually interconnected in the user
program. This makes it possible to generate individual diagnostics messages, for example.
Operational switching signals (such as unlocking commands for protective doors with tumbler)
as well as fault acknowledgment and starting commands can be sent from the PLC to the MSS
3RK3.
Diagnostics display
Pending messages with detailed information shown as text are displayed on the optional
diagnostics display. The diagnostics display enables a time-saving fault detection run of the MSS
3RK3 without connecting to a PG/PC with Safety ES. The cause of a fault can be located quickly
and easily and you can respond directly to it. The diagnostics display can be installed in the
control cabinet door and is operable from the outside. Programming or parameterization of the
diagnostics display is not necessary.
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SIRIUS 3RK3 Modular Safety System
Equipment Manual, 07/2020, NEB926253002000/RS-AC/006