User manual

Publication 1734-UM011A-EN-P - February 2004
About the 1734-AENT Adapter 1-3
Empty Slots and RIUP Situations
The POINT I/O system does not have the ability to detect an empty terminal
base. Because of this, there are numerous situations in which you can
potentially configure a system that is unusable or one that exercises unintended
control. In an attempt to address these situations, you must observe the
following rules for POINT I/O system construction and the removal and
reinsertion of modules.
• A correct POINT I/O system does not have any empty terminal bases.
• After power up, the adapter will not run any I/O until the number of
modules comprising the “chassis” equals the stored “chassis size”.
Because the adapter cannot detect empty terminal bases, it cannot
assume any safe operation until there is a “match” between the number
of modules indicating their presence in the chassis and what the adapter
has saved in non-volatile memory. Actual module identification (i.e.,
electronic keying) will be done when connection establishment requests
are received from the controller(s).
• A module removed under power will not disrupt operation of the
other I/O modules. When a module is removed, the adapter will
determine what has changed. Whenever a module with an active
connection is removed from the POINT I/O system, the adapter will
indicate this by flashing the PointBus Status LED red and report a
minor recoverable fault.
• If more than one contiguous module is removed under power,
connections to all modules in the contiguous missing module set will
be disallowed until all modules are replaced. Because the adapter
cannot detect an empty base, it does not know the physical positioning
of the modules until all the missing modules are replaced.
• If a module separating two sets of contiguous missing modules is
removed, the two sets merge into a single set. All the modules must
be replaced before connections are permitted to any module in the set.
• If modules of different types are removed and returned to the wrong
locations, attempts to connect to these modules will fail during
verification of the electronic ID (providing that keying has not been
disabled).
• If modules of the same type are removed and returned to the wrong
locations, they will accept connections from the controller(s) and be
reconfigured with the correct data once they pass their electronic keying
check.
• The above mentioned removal and return situations exist whether
the system is under power or not. If the system is under power, the
situation arises immediately. If the system is not under power, the
situation arises in the next power cycle.