6.5.3 ASIsafe
The ASIsafe (AS‑Interface Safety at Work) concept allows the integration of safety-related
components in an AS‑Interface network. The use of safety-related AS-i input slaves, safety
monitors and safety-related AS‑i outputs enables the transfer and evaluation of safety-related
data and the safety-related control of actuators on the bus level.
ASIsafe principle of operation
Safety-related signals from sensors (8 x 4-bit code sequences)
Each safety-related AS‑i input slave has its own, unique 8 x 4-bit code sequence to be able to
transmit safety-related signals to a safety monitor. These code sequences must be made known
to the MSS 3RK3 by teaching. The integrated safety monitor listens in to the 8 x 4-bit code
sequences of all safety-related AS‑i input slaves as a passive participant and evaluates them
safely.
You will nd more information about teaching code sequences in Chapter "Teaching the code
sequences (Page 208)."
Safety-related signals to actuators (7 x 4-bit code sequences)
These safety-related signals are transmitted to the safety-related AS-i outputs as 7 x 4-bit code
sequences. For this purpose, the safety monitor simulates a safety-related AS‑i slave with an AS-
i address and a special 7 x 4-bit code sequence. The safety-related output listens out for this 7
x 4-bit code sequence without having an address assigned to it, that is, it behaves like a monitor.
The safety-related output evaluates the 7 x 4-bit code sequences and switches the connected
actuators on or o as required.
Example
The graphic shows a typical structure of an AS‑i-Bus. A safety monitor monitors the 8 x 4-bit code
sequences of an EMERGENCY‑STOP (safety-related AS‑i input slave) and evaluates the safety
information. A safety-related AS‑i slave is integrated in the safety monitor. This slave controls a
safety-related AS‑i output using 7 x 4 bit sequences. The safety-related AS‑i output responds to
the address of the integrated slave and switches the system on or o based on the safety
information using an actuator.
An MSS 3RK3 with AS-i interface can perform any function of these safe AS-i components:
Operation
6.5 Connecting to the AS-i master via AS-Interface
SIRIUS 3RK3 Modular Safety System
204 Equipment Manual, 07/2020, NEB926253002000/RS-AC/006
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