You can use the Transfer function block to prevent sudden changes from being sent to the process. For example, if your process cannot handle a sudden change in flow, the Transfer function can ramp the flow to the new value. You can also use the block to transfer control to a predetermined value when a field value status goes bad.
Application example: Temperature sensor switch
You can use the Transfer function block as an input switch between two temperature sensors. The SELECTOR parameter selects the temperature input based on the level in a tank. The following figure is an example function block diagram for this application:
Figure: Transfer function block diagram example
