Rockwell Automation 1756-IF4FXOF2F ControlLogix High-speed Analog I/O Module - Manual (Page 27)

Rockwell Automation Publication 1756-UM005B-EN-P - January 2013 27
Module Features Chapter 3
Compatible Keying
Compatible Keying indicates that the module determines whether to accept or
reject communication. Different module families, communication adapters, and
module types implement the compatibility check differently based on the family
capabilities and on prior knowledge of compatible products. Release notes for
individual modules indicate the specific compatibility details.
Compatible Keying is the default setting. Compatible Keying allows the physical
module to accept the key of the module configured in the software, provided that
the configured module is one the physical module is capable of emulating. The
exact level of emulation required is product and revision specific.
With Compatible Keying, you can replace a module of a certain Major Revision
with one of the same catalog number and the same or later, that is higher, Major
Revision. If a Major Revision is the same, then make sure that the Minor Revision
is the same or higher than it is configured in the project. In some cases, the
selection makes it possible to use a replacement that is a different catalog number
than the original. For example, you can replace a 1756-CNBR module with a
1756-CN2R module.
When a module is created, the module developers consider the module’s
development history to implement capabilities that emulate those of the previous
module. However, the developers cannot know future developments. Because of
this, when a system is configured, we recommend that you configure your module
using the earliest, that is, lowest, revision of the physical module that you believe
will be used in the system. By doing this, you can avoid the case of a physical