In reply to James Beall:
In reply to dmitriy sagadiev:
James suggestion is a good option, but remember that the non-linear gain is not applied to derivative term, that is, if you are using PI or P controller it will work as you are expecting, but if you are using PID the derivative term will continue to change the output even if the error is less than NL_GAP. If you want only integral action to be "stopped" inside a SP band, you can use also I_DEADBAND (integral deadband) parameter quite simply.
In reply to Rafael Rebouças de Araujo:
In reply to kravindranath:
Good idea also! Note that a Reset of "0" is VERY fast integral, to turn it off, you put a large number in the Reset. However, no need to do this since the Integral (Reset) and Derivative (Rate) are also stopped when the Gain is 0. However, note that since the DeltaV PID is a positional implementation, if the Gain is changed from 0 to X when there is an error, the OUT will change by Error*X in a first order manner with a time constant = Reset. However, You can avoid this initial movement by using the PID Structure "I on Error, PD on PV"! (Note that this structure change will not work on the Nonlinear Gain option since when this option is activated, the P Gain is always applied to the Error.) There is also a Deadband on the Gain Scheduler to transition from one tuning set to the next.