Is it possible to have redundant servers with Compact HMI 800?
This is not possible, The Compact HMI Server do not Support Redundancy, remember the Compact HMI is selling as a HMI for Basic Operation and Supervision with the advantage of some important feature like Full Audit trail, Calculation Engine, SMS & Email messaging, etc. that are included in the base license.
This product is made for small and medium systems where the supervision or control from the HMI is not critical.
If you need a solution equivalent but with redundancy you should use 800xA