Rockwell Automation Publication 1756-PM004D-EN-P - September 2012 13
Communicate with I/O Modules Chapter 1
Exact Match
Exact Match keying requires all keying attributes, that is, Vendor, Product Type,
Catalog Number, Major Revision, and Minor Revision, of the physical module
and the module created in the software to match precisely in order to establish
communication. If any attribute does not match precisely, I/O communication is
not permitted with the module or with modules connected through it, as in the
case of a communication module.
Use Exact Match keying when you need the system to verify that the module
revisions in use are exactly as specified in the project, such as for use in highly-
regulated industries. Exact Match keying is also necessary to enable Automatic
Firmware Update for the module via the Firmware Supervisor feature from a
Logix5000 controller.
In the following scenario, Exact Match keying prevents I/O communication:
The module configuration is for a 1756-IB16D module with module revision 3.1.
The physical module is a 1756-IB16D module with module revision 3.2. In this case,
communication is prevented because the Minor Revision of the module does not
match precisely.
Changing electronic keying selections online may cause the I/O Communication
connection to the module to be disrupted and may result in a loss of data.
Module Configuration
Vendor = Allen-Bradley
Product Type = Digital Input
Module
Catalog Number = 1756-IB16D
Major Revision = 3
Minor Revision = 1
Physical Module
Vendor = Allen-Bradley
Product Type = Digital Input Module
Catalog Number = 1756-IB16D
Major Revision = 3
Minor Revision = 2
Communication is prevented
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