Siemens SICAM AK Manual page 80

Redundancy via SCA-RS
The message can be parameterized in the OPM (SICAM 1703 + Ax 1703 system functions)
under Redundancy control message with the attributes Control_function_(RED) (listening
mode) and Failure_behavior_(RED).
There is only one message, which is valid for the entire automation unit.
Based on the content of the data the entire automation unit is switched
•
to normal mode (binary information = 1) or
•
to listening mode (binary information = 0).
If the user data message is received with NT-Bit set, either the state is retained or the
automation unit is switched to listening mode (can be parameterized in the failure behavior).
The status of listening mode is also forwarded as return information.
Key switch: with CPU redundancy (application-related key-operated switch)
With redundancy configurations it should be possible, that an automation unit or interfaces are
switched either
•
active
•
passive
•
or automatic (required state of the voter)
over a key-operated switch.
This takes place when using the SCA-RS directly through wiring over the SCA-RS.
With application-related voting, this can take place in the application when generating the A/P-
control message.
With CPU redundancy however, it is possible to read this state over an input module or to
determine it via communication from a higher-level station and send it to the central
redundancy processing by means of a user data message (single point information).
The message can be parameterized in the OPM (SICAM 1703 + Ax 1703 system functions)
under Redundancy control message with the attributes Control_function_(RED) (key switch),
Failure_behavior_(RED) and BSE_(RED).
The key-operated switch is valid for the parameterized basic system element and its protocol
elements. A message must be routed to both basic system elements, since the status of the
key-operated switch can only be determined from both messages:
•
both binary informations 0 = Automatic
•
one binary information 1 = C-CPU concerned and its protocol elements permanently
switched active by the key-operated switch, the other passive
•
both binary informations 1 = Faulty position, is treated as a failure (NT-Bit set)
If a faulty position is detected an error of the class External is set.
If the user data message is received with NT-Bit set, either the state is retained or switched to
Automatic (can be parameterized in the failure behavior).
80
Unrestricted SICAM RTUs, SICAM AK Redundancy
Edition 10.2016, DC2-026-2.07