I think your case is also manufacturer specific on what happens during a failure. For Loytec some options:
Originally Posted by CraziFuzzy
1. Use smart programmable I/O. Each I/O has an individual program put into each specific I/O running autonomously. Each I/O program is backed up to the L-INX with intercommunication. I/O is hot swappable and auto-downloads from the L-INX. The L-INX can be backed up (week/day/hourly) so that replacement for that is setting the same IP address as the existing controller. The complete configuration is restored from the latest backup.
2. Use connected I/O. Still hot swappable. L-INX backed up but if the L-INX goes down the connected I/O default to failsafe.
3. Use independent programmable I/O and Bind/Map data sharing between them. Default to failsafe.
I like that Loytec has a backup system. I dont need to use any software or hook up to the device with a PC to replace hardware. I would say this is less field management work. Don't need to think about which tech has what software on his PC.