Most controllers have a way for users to enter the appropriate controller action (CA) for their system (direct or reverse). A direct acting controller increases the controller output (+) for a positive controller error (+) and decreases the controller output (-) for a negative controller error (-). Conversely, a reverse acting controller decreases the controller output (-) for a positive controller error (+) and increases the controller output (+) for a negative controller error. Our controller calculates the controller error as e(t) = mv sp (mv is the real time value of the measured variable and sp is our setpoint.

Determine the appropriate controller action for each lab station: level, pressure and temperature. Clearly explain what conditions exist for (+) and (-) errors and how the controller action (+) or (-) will help to reduce these errors. (Temperature control stations need to characterize both final control elements (ASSR and CV).