Siemens SIRIUS 3RK3 - Representation of Safety-Related AS-I Outputs

6.5.7.7 Representation of safety-related AS-i outputs
The MSS 3RK3 with AS‑i interface can represent a maximum of 31 safety-related AS-i outputs.
Safety-related AS‑i outputs do not have an explicit address on the AS‑i bus. A safety-related AS‑i
output behaves like a safety monitor that responds to a 7 x 4 bit code sequence of an AS‑i
address. In this way, actuators can be switched safely.
Switching response of safety-related output signals
No zero signal has to be transferred in order to switch between two output signals of an AS-i
output slave. The active output stays on until the full code sequence of another output of this
output slave has been received. If an error occurs while the new code sequences are being
transmitted or if a zero sequence is transmitted, all outputs will be deactivated.
Terminal designation in Safety ES
The signal source (e.g., a safety monitor or an additional MSS 3RK3 with AS-i interface) transmits
a 7 x 4-bit code sequence depending on the AS‑i address, which is received and evaluated by the
MSS 3RK3. The input values are available for processing on the logical terminals in the logic and
can be con󹪝gured as required in the Safety ES. In this way, the MSS 3RK3 controls its own
outputs. The terminal designations of the input cells for this are as follows:
Terminal designation of the input cells Explanation
ASI#xx_F-OUTc Signal, for example, from an AS-i safety monitor V3.0 or
from another MSS 3RK3 with AS-i interface
ASI#xx_AUXm Modulated, non-safety-related auxiliary control signal
m: Auxiliary signal 1 or 2
xx: AS-i address
c: Channel number of the AS-i slave process image, here the identi󹪝er OUT is selected as it is not a sensor
value but a preprocessed signal.
Operation
6.5 Connecting to the AS-i master via AS-Interface
SIRIUS 3RK3 Modular Safety System
224 Equipment Manual, 07/2020, NEB926253002000/RS-AC/006