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When you say "An input card failed", what exact model of input card are you describing ? What "remote rack" are you talking about; is it POINT I/O, or something else ? Be as specific as you can.
One of the features that we take for granted in the ControlLogix platform is the ability to "drill down" through a controller to access a lower-level network.
In the SLC-5/0x controllers this is possible with the "1747-SDNPT" driver, but even that driver relies on the correct 1747-SDN firmware, configuration data file sizes, and RSLinx revision, as well as an active and correctly installed network.
Ideally you'll have a direct connection to the network via a serial (1770-KFD) or card (1784-PCD) or USB (1784-U2DN) connection to access both the Scanner and the input card you're trying to replace.
Once you do establish communications, it might be as simple as de-selecting the "Electronic Keying" section of the 1747-SDN Scanlist entry for that input module so that the system will accept any firmware revision.