6.5.7.8 MSS 3RK3 Advanced as the safety monitor
Function
The MSS 3RK3 with AS-i interface also performs the function of a safety monitor. The safety
monitor is at the heart of ASIsafe. It monitors the information transmitted through the AS-
Interface (master call, response from AS-i slave).
Note
Minimum expanded conguration of the AS‑i bus
At least four AS‑i slaves must be connected to the AS‑i bus to ensure that the safety-related
AS‑i input slaves are correctly evaluated. It does not matter whether the additional slaves are
safety-related or standard slaves. If fewer than four real AS-i slaves exist, the other slaves that are
needed can be simulated by MSS 3RK3.
Evaluation in the logic of the MSS 3RK3
The evaluation of the information produces the values in the input cells. These are subsequently
further processed in the processing logic of the MSS 3RK3.
To be able to interconnect a non-safety-related AS-i slave, the "Monitor non safe I/O" checkbox
must be selected in the subsystem (navigation window) in the properties of the AS-i slave.
The signals of a safety-related AS‑i input slave are composed partly of safety-related signals and
partly of non-safety-related signals. To be able to interconnect the non-safety-related
information of a safety-related slave, the "Monitor non safe I/O" checkbox must be selected in the
subsystem (navigation window) in the properties of the slave, like for the non-safety-related
slave.
Note
Simulated AS-i slaves
Where values from output terminals of simulated slaves are used again as an input in the logic,
the input value is not derived using the monitor function but the value of the output terminal is
used. This means that the value will be available to the safety logic in the next processing cycle
of the MSS 3RK3. There are no asynchronous dependencies between the cycle time of the
MSS 3RK3 and the cycle time of the AS-i bus.
Reference
You will nd additional information on ASIsafe on the Internet (
http://
support.automation.siemens.com/WW/view/en/12834652/133300).
Operation
6.5 Connecting to the AS-i master via AS-Interface
SIRIUS 3RK3 Modular Safety System
226 Equipment Manual, 07/2020, NEB926253002000/RS-AC/006
To Next Page
Loading...
Need help?
General
