Siemens SIMATIC PCS 7 Function Manual page 50

Fault-tolerant Solutions in PCS 7
3.3 Solutions for communication
High Speed Redundancy (HSR - obsolete)
Obsolete term: This term can be found in older firmware versions of Industrial Ethernet
switches. The functionality corresponds to that of HRP. You can find additional information
about High Speed Redundancy and High Speed Redundancy Protocol in the documentation
of the Industrial Ethernet switches.
Media Redundancy Protocol (MRP)
For redundant coupling in a fieldbus ring based on PROFINET, all devices must support MRP.
Configuration of the watchdog time
When a transmission path fails, it may take up to 200 ms to reconfigure the network (switching
to the redundant transmission path).
Increase the watchdog time for each station by adjusting the following values:
● Select the "fixed update time" setting.
● Increase the update time to a value that is less than the fastest update of the process image
partition (PIP) for this station.
● Increase the number of accepted update cycles with missing I/O data, so that the watchdog
time is > 200 ms.
See also http://support.automation.siemens.com/
WW/view/en/55422236)
Additional information
● You can find information about HRP and MRP in the documentation of the Industrial
Ethernet switches.
● You can find information about High-availability Seamless Redundancy (HSR) in the
section "Redundant, fault-tolerant terminal bus based on the Parallel Redundancy Protocol
(PRP) (Page 54)".
See also
How to configure the redundant terminal bus on the basis of the Parallel Redundancy
Protocol (Page 107)
How to configure a fault-tolerant plant bus (Page 112)
How to configure a media-redundant fieldbus on the basis of PROFINET (Page 120)
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(http://support.automation.siemens.com/
Fault-tolerant Process Control Systems (V8.1)
Function Manual, 11/2014, A5E34878832-AA