With a switched connection, the I/O modules are connected with both central devices via two interface modules. Both central devices are active during fault-free operation.
When writing the outputs, the data from both channels is accepted but only the data of the preferred channel is forwarded to the outputs.
The function of the system stays completely intact even if, for example, a central device and/or the connected PROFINET network and/or one or several of the interface modules in the ET 200 connected to this network fail.
The failure of a central device can be tolerated regarding communication.
Additional benefit of fault tolerance
Availability can be increased even more if both CPUs are set up completely separate from each other.
The distance between the systems can be up to 10 kilometers (16 miles).