Failure, Switchover And Reintegration Of High Availability Components; Failure Of Redundant Interface Modules; Failure Of Redundant I/O Modules - Siemens Simatic PCS 7 Function Manual

Failure, switchover and reintegration of high
availability components
7.1 I/O
7.1.1

Failure of redundant interface modules

Functionality
Interface modules can be configured redundantly in the distributed I/O device (ET 200M, ET
200iSP, ET 200SP HA). The interface modules provide the interface to the automation system
through the fieldbus system at the CPU. When there are two interface modules, in other words,
the system has been configured with "Redundancy", if one of the two modules fails, the other
interface module takes over the automation process without interruption.
Failure
If the active interface module fails, a bumpless switchover to the redundant interface module
is performed. In the switchover, the master identification changes from the failed interface
module to the interface module that is now active.
If the redundant interface module fails, the master identification does not change.
Hot restart
When the failed interface module restarts, the redundant interface module keeps the master
identification. The master identification changes back to the now replaced or repaired module
only if the redundant interface module fails.
7.1.2

Failure of redundant I/O modules

Functionality
As soon as an error occurs in one of the redundantly configured modules, there is a bumpless
switchover to the second module, which then takes over the signal processing.
High Availability Process Control Systems (V9.0)
Function Manual, 05/2017, A5E39221836-AA
7
199