119.What will be operation logic for selection of transmitter when redundant transmitters are used for control?

When both transmitters are healthy, operator can select any transmitter or average value for control (on Auto).When one transmitter fails, the control shall changeover to the other healthy transmitter and the alarm (failure) status to be notified to the operator. When both transmitters are faulty OR there is a deviation between the two transmitter readings (beyond specified margin), the control loop shall be forced to Manual and Failure to be alarmed to operator including forced manual status.