Rockwell Automation 1715-OF8I Redundant I/O System User Manual - Manual (Page 266)

266 Rockwell Automation Publication 1715-UM001C-EN-P - March 2014
Appendix B Electronic Keying
Exact Match
Exact Match keying requires all keying attributes, that is, Vendor, Product Type,
Product Code (catalog number), Major Revision, and Minor Revision, of the
physical module and the module created in the software to match precisely 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.
IMPORTANT Changing electronic keying selections online can cause the I/O
communication connection to the module to be disrupted and can result in
a loss of data.
EXAMPLE 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.
Module Configuration
Vendor = Allen-Bradley
Product Type = Digital Input Module
Cat. No. = 1756-IB16D
Major Revision = 3
Minor Revision = 1
Physical Module
Vendor = Allen-Bradley
Product Type = Digital Input Module
Cat. No. = 1756-IB16D
Major Revision = 3
Minor Revision = 2
Communication is prevented