I/O configuration variants
6.8 Media redundancy
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
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6.7.3
Evaluating the passivation status
Procedure
First, determine the passivation status by evaluating the status byte in the status/control
word "FB_RED_IN.STATUS_CONTROL_W". If you see that one or more modules have
been passivated, determine the status of the respective module pairs in
MODUL_STATUS_WORD.
Evaluating the passivation status using the status byte
The status word "FB_RED_IN.STATUS_CONTROL_W" is located in the instance DB of FB
450 "RED_IN". The status byte returns information on the status of the redundant I/Os. The
assignment of the status byte is described in the online help for the respective block library.
Evaluating the passivation status of individual module pairs by means of MODUL_STATUS_WORD
MODUL_STATUS_WORD is an output parameter of FB 453 and can be interconnected
accordingly. It returns information on the status of individual module pairs.
The assignment of the MODUL_STATUS_WORD status byte is described in the online help
for the respective function block library.
6.8
Media redundancy
Media redundancy is a function for ensuring network availability and thus contributes to
increasing the plant availability. Redundant transmission links in a ring topology ensure that
an alternative communication path is always available if a transmission link fails. Following a
fault in one transmission link, data traffic can resume over the alternative link after a
maximum reconfiguration time of 200 ms.
For the components involved, you can enable the media redundancy protocol (MRP) in HW
Config. The components (IO devices, switches) must support MRP. MRP is a component of
the PROFINET IO standardization according to IEC 61158.
Note
Support of PRP (Parallel Redundancy Protocol) or MRPD (Media Redundancy Protocol
Domain) does not equal MRP functionality or vice versa.
In the case of media redundancy with MRP, one device is specified as the media
redundancy manager (MRM) in HW Config. All other devices are redundancy clients.