Conditions

An I/O connection can be lost to a BMECRA31210 or BMXCRA312•0 under these conditions:

  • Performing a hot swap by replacing an adapter module with the same type.

  • There is no RIO cable connection.

  • The I/O connection is closed while the CPU is reconfigured.

Remote Adapter Fallback

In some instances, the RIO adapter module can lose I/O connections for a period longer than the configured hold up time. During the hold up, the adapter tries to get IP and configuration parameters from the BME•58••40 CPU. If the adapter does not obtain those parameters during the hold up time, the following happens:

  • inputs: retain last known values

  • outputs: set to configured fallback value

NOTE:

  • Configure the hold up time on the Control Expert Parameter tab. For more information, refer to your system planning guide.

  • In hot standby systems, this situation occurs only when the adapter module loses the connection to the primary and secondary CPUs.

NOTE: Configure the hold up time on the Control Expert Parameter tab. For more information, refer to your system planning guide.

Adapter Hot Swap

From the system point of view, during an adapter hot swap, when the adapter is removed the I/O values go to fallback values. When the new adapter inserted and switches on and is configured, the I/O values reset to their values before the hot swap.

To reduce the number of transitions after a hot swap, set the configured fallback state the same as the default fallback state (module powered-on but not configured) before performing the hot swap.