Method of and apparatus for nonobtrusively obtaining on-line measurements of a process control device parameter

An apparatus for determining a device parameter associated with a process control device when the process control device is connected on-line within a process, the apparatus comprising:

• means for detecting a change in a control signal that controls the process control device;
• means for measuring an indication of the response of the process control device to the change in the control signal;
• and
• means for calculating the device parameter from the detected change in the control signal and the response indication;
• wherein the device parameter is dead time and wherein the calculating means includes means for determining the dead time of the process control device.

An apparatus for determining a device parameter associated with a process control device when the process control device is connected on-line within a process, the apparatus comprising:

• means for detecting a change in a control signal that controls the process control device;
• means for measuring an indication of the response of the process control device to the change in the control signal;
• and
• means for calculating the device parameter from the detected change in the control signal and the response indication;
• wherein the device parameter is response time and wherein the calculating means includes means for determining the response time of the process control device.

An apparatus for determining the dead band of a process control device when said process control device is connected within a process to control a process variable, the apparatus comprising:

• means for detecting successive values of a control signal that controls the process control device while the process control device is connected on-line within the process;
• means for measuring an indication of a response of the process control device to each of the successive values of the control signal;
• and
• means coupled to the detecting means and to and the measuring means for determining the dead band of the process control device from the successive values of the control signal and from the response indications associated with the successive values of the control signals to produce a signal indicative of the dead band.

A method of determining a device parameter associated with a process control device when the process control device is connected on-line within a process and is controlled by a control signal, the method comprising the steps of:

• detecting a change in the control signal;
• measuring an indication of the response of the process control device to the change in the control signal;
• and
• calculating the device parameter from the detected change in the control signal and from the response indication to produce a signal indicative of the device parameter.

A method of determining a device parameter associated with a process control device when the process control device is connected on-line within a process and is controlled by a control signal, the method comprising the steps of:

• detecting a change in the control signal;
• measuring an indication of the response of the process control device to the change in the control signal;
• and
• calculating the device parameter from the detected change in the control signal and from the response indication;
• wherein the device parameter is dead time and wherein the step of calculating includes the step of determining the dead time of the process control device.

A method of determining a device parameter associated with a process control device when the process control device is connected on-line within a process and is controlled by a control signal, the method comprising the steps of:

• detecting a change in the control signal;
• measuring an indication of the response of the process control device to the change in the control signal;
• and
• calculating the device parameter from the detected change in the control signal and from the response indication;
• wherein the device parameter is response time and wherein the step of calculating includes the step of determining the response time of the process control device.

An apparatus for determining a device parameter associated with a process control device when the process control device is connected on-line within a process control system having a processor, the apparatus comprising:

• a computer-readable memory;
• and
• a software routine stored on the computer-readable memory and adapted to be executed by the processor, wherein the software routine performs the steps of;
• detecting a change in a control signal that controls the process control device;
• determining an indication of the response of the process control device to the change in the control signal;
• and
• calculating the device parameter from the detected change in the control signal and the response indication.