Allen-Bradley 1756-L61 ControlLogix 5561 Programming Manual page 18

Chapter 1 Communicate with I/O Modules
16
In the following scenario, Compatible Module allows I/O communication:
EXAMPLE
The module configuration is for a 1756-IB16D module with module revision 2.1.
The physical module is a 1756-IB16D module with module revision 3.2. In this case,
communication is allowed because the major revision of the physical module is
higher than expected and the module determines that it is compatible with the
prior major revision.
Module Configuration
Vendor = Allen-Bradley
Product Type = Digital Input
Module
Catalog Number = 1756-IB16D
Major Revision = 2
Minor Revision = 1
Physical Module
Vendor = Allen-Bradley
Product Type = Digital Input Module
Catalog Number = 1756-IB16D
Major Revision = 3
Minor Revision = 2
Changing electronic keying selections online may cause the I/O communication
IMPORTANT
connection to the module to be disrupted and may result in a loss of data.
Rockwell Automation Publication 1756-PM004D-EN-P - September 2012
Communication is allowed