Modify a step response

An expert user with a good knowledge of the delay and time constants associated with inputs to the process can modify a step response and create new control for a model. There are three methods you can use to modify a step response:

Add and plot points to a step response to redefine the response curve.
Design a new response (must know the process gain, deadtime, and time constants).
Edit a step response's coefficients.

Select Expert from the Options menu to identify yourself as an expert user.
Select a step response.
The individual step response view shows the process output (controlled/constraint variable) response (in percent or engineering units) to a unit step change (in percent or engineering units) in the input (manipulated/disturbance variable), with all other inputs held constant.
Select Percent, and choose from the following methods to edit the response:
- Select Design Resp to open the Design Response dialog. Use the context sensitive help for help on the fields in this dialog.
- Select Edit Coeff to directly edit the step response's coefficients.
- Right-click in the graph, select Add Point or Add Points, and then click Plot to plot a smooth curve through the points you added. (You must add at least three points to use the Plot command.)
Click Clear to clear any changes you made.
Click Save to save the new response and replace the original response.

Once you have modified a step response, you can verify the accuracy of the model and generate control to update the MPC configuration for the new model.