Rockwell Automation 1738-AENTR, Series B POINT I/O and ArmorPOINT I/O Dual Port EtherNet/IP Adapters User Manual - Manual (Page 13)

Rockwell Automation Publication 1734-UM017B-EN-P - October 2013 5
Overview of the 1734 POINT and 1738 ArmorPOINT EtherNet/IP Adapters Chapter 1
Each time the adapter is powered up, the adapter compares the number of I/O
modules present on its backplane to the chassis size value from non-volatile
memory. The adapter does not allow any I/O connection until the number of
I/O modules present equals the chassis size value minus one for the adapter itself.
Adapter Replacement
Note that during a connection request from the controller, the chassis size setting
is not communicated to the adapter. You must always set this chassis size using a
separate operation. This includes situations when you are replacing an adapter.
The adapter does not allow any I/O connections until it is configured with the
appropriate chassis size and the proper number of POINT I/O or
ArmorPOINT I/O modules are present.
Empty Slots and RIUP Situations
The POINT I/O system cannot detect an empty terminal base. For this reason,
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
I/O system construction and the
removal and reinsertion of modules.
• A correct I/O system does not have any empty terminal bases.
• After you cycle power, the adapter will not allow any I/O connections
until the number of modules comprising the chassis plus one for the
adapter equals
the stored chassis size.
– 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 because it cannot detect
empty terminal bases.
– Actual module identification (such as, electronic keying) is done when
connection establishment requests are received from the controller or
controllers.
• A POINT I/O module removed under power does not disrupt operation
of the other I/O modules. On the other hand, ArmorPOINT I/O
modules are not intended to be removed under power.
–
When you remove a module, the adapter detects what changed.
– Whenever you remove a module with an active connection from the
POINT I/O system, the adapter indicates this by flashing the
POINTBus Status LED red and reports a minor recoverable fault.
• If more than one contiguous module is removed under power, connections
to all modules in the contiguous missing module set are 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.