Rockwell Automation 1715-OF8I Redundant I/O System User Manual - Manual (Page 17)

Rockwell Automation Publication 1715-UM001C-EN-P - March 2014 17
Redundancy System Overview Chapter 1
Base Unit Structure
The adapter base unit is always the leftmost base unit in the connection chain.
The total length of the base unit connection chain, including all expansion cables
cannot exceed 10 m (32.81 ft).
A adapter module always occupies slot 0 or 1.
An adapter base unit can support up to 8 I/O base units (up to 24 I/O modules).
1715-AENTR Adapter Modules
The leftmost adapter module position, or slot, is 0. The rightmost adapter
module slot is 1. Slots 0 and 1 of the system are always occupied by one
redundant adapter module pair, and are designated as ‘A’ for the primary adapter
partner and ‘B’ for the secondary adapter partner. This system is designed to run
with two adapter modules. It can run with one adapter module for a limited time
while replacing a damaged module, but ideally, needs both adapter modules
running simultaneously.
I/O Modules
I/O module slots are numbered from 2…25, based on distance from the adapter
base unit. If duplex I/O module pairs are used, the two modules of the pair must
be in adjacent slots. The left, lower slot number is considered the slot number and
address for the pair. Any combination of simplex modules and duplex pairs can be
used in one or more connected I/O bases units.
IMPORTANT There is no method for configuring a system to use only one 1715-AENTR
adapter module. If you use only one 1715-AENTR adapter module, the unused
module generates errors.
A ‘partner’ adapter module can be installed or removed for replacement, while
the 1715 Redundant I/O System is operational. During replacement of the
module, there is a one-time, up to a maximum 500 ms, delay to the system.
IMPORTANT A ‘partner’ I/O module can be installed or removed while the 1715 Redundant
I/O System is operational, without impact to the rest of the system.