Abstract: A lead-lag input filter is connected ahead of a positioner feedback loop having one or more valve accessories, such as a volume booster or a QEV, to overcome slow dynamics experienced by the accessories when receiving low amplitude change control or set point signals. A user interface is connected to the lead-lag input filter and enables an operator or other control personnel to view and change the operating characteristics of the lead-lag input filter to thereby provide the control loop with any of a number of desired response characteristics.

Abstract: A diagnostic system and method for a field device in a process control apparatus is provided. At least one sensor is associated with the process control apparatus, and a computer is adapted to receive data from the sensor and to detect an occurrence of a predetermined process event. A memory device is operatively connected to the computer and adapted to store sensor data received by the computer at a time corresponding to the occurrence of the predetermined process event.