Solution:
If you physically remove an RTA from a host system the configuration information is not automatically removed. The TTY devices are logically matched to the unique ID contained in the RTA.
If you replace the removed RTA with another RTA (with the same number of ports) then you can transfer the configuration from the removed unit to the new unit).
To do so run the rioadapt utility to adapt the configuration of the defective RTA to the new replacement RTA.
AIX
Under the Remote Terminal Adapter option select the RIO Remote Terminal Adapter -> Adapt new Specialix RIO RTA.
All other Unix systems
At the command prompt type "rioadopt" if you have removed only one RTA, and type "rioadopt -i" (interactive) if you have remove multiple units.