Rockwell Automation 1756-OF8I ControlLogix Eight-channel Isolated Analog I/O Modules - Manual (Page 28)

28 Rockwell Automation Publication 1756-UM540A-EN-P - May 2014
Chapter 2 ControlLogix Isolated Analog I/O Module Features
Electronic Keying
The electronic keying feature automatically compares the expected module, as
shown in the I/O Configuration tree, to the physical module before I/O
communication begins. You can use electronic keying to help prevent
communication to a module that does not match the type and revision expected.
For each module in the I/O Configuration tree, the user-selected keying option
determines if, and how, an electronic keying check is performed. Typically, three
keying options are available:
• Exact Match
• Compatible Keying
• Disable Keying
You must carefully consider the benefits and implications of each keying option
when selecting between them. For some specific module types, fewer options are
available.
Electronic keying is based on a set of attributes unique to each product revision.
When a Logix5000 controller begins communicating with a module, this set of
keying attributes is considered.
Attribute Description
Vendor The manufacturer of the module, for example, Rockwell Automation/Allen-Bradley.
Product Type The general type of the module, for example, communication adapter, AC drive, or digital
I/O.
Product Code The specific type of module, generally represented by its catalog number, for example,
1756-IRT8I.
Major Revision A number that represents the functional capabilities and data exchange formats of the
module. Typically, although not always, a later, that is higher, Major Revision supports at
least all of the data formats supported by an earlier, that is lower, Major Revision of the
same catalog number and, possibly, additional ones.
Minor Revision A number that indicates the module’s specific firmware revision. Minor Revisions
typically do not impact data compatibility but can indicate performance or behavior
improvement.