218 Rockwell Automation Publication 1756-UM001M-EN-P - February 2012
Appendix B Using Electronic Keying
If you use Disabled Keying, you must take full responsibility for understanding
whether the module being used can fulfill the functional requirements of the
application.
In the following scenario, Disable Keying prevents I/O communication:
The module configuration is for a 1756-IA16 digital input module. The physical module is a
1756-IF16 analog input module. In this case, communication is prevented because the
analog module rejects the data formats that the digital module configuration
requests.
Module Configuration
Vendor = Allen-Bradley
Product Type = Digital Input Module
Catalog Number = 1756-IA16
Major Revision = 3
Minor Revision = 1
Physical Module
Vendor = Allen-Bradley
Product Type = Analog Input Module
Catalog Number = 1756-IF16
Major Revision = 3
Minor Revision = 2
Communication is prevented.