Determining Series C I/O block redundancy
The IOM blocks represent instances of the I/O Module hardware that reside on the I/O Link
network. There is a specific IOM block for each I/O Module type supported in Experion.
The IOM block is used to:
l configure the network address (the IOMNUM) of the IOM device.
o If the IOM is configured to be redundant, you enter only one IOMNUM. In either case,
only one block is created which handles communication to and from both physical
IOMs.
o The hardware design uses a set of push-in IOMNUM identifiers to reduce the chance
of duplicate IOMNUMs on the same link.
o Each IOM block generates system events and alarms for soft failures, IOM
synchronization, and IOM switchover.
Figure 9.1 Defining redundancy from the Main tab
9.2 Switchover and Secondary readiness
A switchover describes the process where a Secondary Series C module assumes the Primary
state, and the Primary Series C module assumes the appropriate Secondary state of readiness,
depending upon what triggered the switchover. A switchover can be triggered immediately upon
the detection of a fault in the Primary or upon the receipt of an operator command.
The ability of a Secondary Series C module to take over the assigned control functions of the
Primary depends upon which one of the following readiness states reflects its current state.
If Secondary
redundancy
state is
Then, the Secondary module
NotSynced
Not
synchronized
Cannot assume the Primary state. This is a state of non-readiness. Switchover has
not occurred. Ensure redundancy has been selected on the IOMs Main tab.
FoInProg
SwapInProg
Cannot assume the Primary State. In this state, the Secondary module is copying
database information from the Primary.
