Schneider Electric 890USE17700 - Manual (Page 153)

Advanced Configuration Features
890USE17700 April 2004 153
Configuring Mandatory Modules
Summary As part of a custom configuration, you can assign mandatory status to any I/O
module or preferred device on an island. The mandatory designation indicates that
you consider the module or device critical to your application. If the NIM does not
detect a healthy mandatory module at its assigned address during normal
operations, the NIM stops the entire island.
Specifying
Mandatory
Modules By default, the Advantys STB I/O modules are in a non-mandatory (standard) state.
Mandatory status is enabled by clicking on the mandatory checkbox on a module or
preferred device’s parameters property sheet. Depending on your application, any
number of modules that your island will support can be designated as mandatory
modules.
Effects on Island
Bus Operations The following table describes the conditions under which mandatory modules affect
island bus operations and the NIM’s response:
Note: The Advantys configuration software is required if you want to designate an
I/O module or a preferred device as a mandatory module.
Condition Response
A mandatory module fails during
normal island bus operations. The NIM stops the island bus. The island enters fallback
mode (See Island Fallback Scenarios, p. 161). I/O
modules and preferred devices assume their fallback
values.
You attempt to hot swap a
mandatory module. The NIM stops the island bus. The island enters fallback
mode. I/O modules and preferred devices assume their
fallback values.
You are hot swapping a standard
I/O module that resides to the left
of a mandatory module on the
island bus, and the island loses
power. When power is restored, the NIM attempts to address the
island modules but must stop at the empty slot where the
standard module used to reside. Because the NIM is now
unable to address the mandatory module, it generates a
mandatory mismatch error and the island fails to restart.