TXP-CLC Course
3
The concept for high availability requirements
Industrial Ethernet with single fault tolerance
M
M
AS AP
AS AP
OM PU
OM PU
Monitoring
Monitoring
logic
logic
Starcoupler
Starcoupler
One fault on the bus
causes the monitoring
logic to connect the
bus line
One fault on the bus
One fault on the bus
causes the monitoring
causes the monitoring
logic to connect the
logic to connect the
bus line
bus line
After repair the
monitoring logic
disconnects the bus line
again
After repair the
After repair the
monitoring logic
monitoring logic
disconnects the bus line
disconnects the bus line
again
again
➣
➣
➣
➣
Starcoupler
Starcoupler
Starcoupler
Starcoupler
Provided that the bus system is operating error-free, the data packets from a
transmitting participant are transferred over the entire length of the bus and the
monitoring logic receives identical bus signals from both directions. In the event
of a fault, such as a wire-break or failure or shutdown of a star coupler, the data
stream is not received from one direction. Data is not received temporarily by
participants that are connected between the location of the fault and the module
that contains the monitoring logic.
The monitoring logic responds by connecting the open circuit within the module,
so that all participants are able to communicate with each other once more.
When the fault that interrupted the transfer path has been rectified, the virtual
ring is re-established in that the monitoring logic disconnects the path again. With
a virtual ring, single-fault tolerance can be achieved that is comparable to a bus
system that is implemented with a redundant transfer medium without the need
to implement a second transfer medium. One fault in the cable of the virtual ring
is tolerated.
Training Center
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