Method of and apparatus for deterministically obtaining measurements

A control valve having a moveable valve member utilized in connection with an operating process to receive a control signal, the control valve comprising:

• a switch controller that monitors a process signal during operation of the operating process;
• a signal generator that generates a diagnostic test signal;
• a switch responsive to the switch controller to replace the control signal with the diagnostic test signal during operation of the operating process;
• a position sensor in communication with the moveable valve member to generate a position signal representative of the position of the moveable valve member;
• and
• an analyzer unit that determines a device parameter from the diagnostic test signal and the position signal.

A method of determining a device parameter associated with a process control device while the process control device is utilized in connection with an operating process to receive a control signal, the method comprising the steps of:

• monitoring a process signal during operation of the operating process to determine whether the process signal is substantially stable;
• generating a diagnostic test signal;
• replacing the control signal with the diagnostic test signal during operation of the operating process if the process signal is substantially stable;
• receiving an indication of the response of the process control device to the diagnostic test signal;
• and
• determining the device parameter from the response indication.