8.2 
Redundancy configuration restrictions 
There are a number of restrictions imposed to device configuration for the purpose of 
providing device redundancy. 
 
C300 Controller Device Index 
The primary C300 Controller of a redundant controller pair and non-redundant C300 
Controllers must be configured with an odd numbered Device Index.  Control Builder 
will enforce this restriction.  The secondary C300 Controller of a redundant controller 
pair is assigned an even Device Index (primary controller Device Index plus 1) upon the 
configuration of the primary controller. 
The Device Index switches on the primary and secondary controller IOTAs must be set 
according to their configured Device Indexes.  If the Device Index switches on a primary 
or non-redundant C300 IOTA are set to an even number address or do not match the 
configured Device Index, then an error is generated when loading the controller and the 
load operation is aborted. 
Refer to the section C300 Controller Configuration for details on controller 
configuration. 
 
IOLINK interface considerations 
In a C300 redundant controller pair, a C300 IOLINK function block which is configured 
to support a specific IO Family, (IOLTYPE parameter set to SERIES_8_IO_TYPE) is 
verified in the secondary controller by the primary controller.  After the primary 
controller synchronizes the configured IOTYPE, the primary uses the IOLink interface to 
communicate with the secondary controller to verify that the associated IOLink interface 
on the secondary is configured to support the same IO Family.  If the IOLink cables are 
not connected between the primary and secondary controllers, initial-sync failures will 
result. 
 
Series 8 FIM restrictions 
 
The Series 8 FIM control hardware is available with a non-redundant IOTA that accepts a single 
Series 8 FIM module and a redundant IOTA that contains connections for accepting two Series 8 
FIM modules. 
 
Non-redundant IOTA 
A non-redundant Series 8 FIM module can be configured with either an odd or even Device 
Index. The Device Index switches on the associated non-redundant IOTA must be set according 
to the module's configured Device Index. A Series 8 FIM module installed on a non-redundant 
IOTA cannot be configured as redundant. A status bit (RDNCAPABILITY parameter) indicates