Rockwell Automation 1756-XXXX ControlLogix Analog I/O Modules - Manual (Page 39)

Publication 1756-UM009C-EN-P - December 2010 39
ControlLogix Analog I/O 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.
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.
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.
IMPORTANT
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