Design and simulation of a Foundation Fieldbus State Estimator Function Block (FFSEFB), which can control and minimize the system estimated states' error is proposed in this paper. Due to the importance of the foundation fieldbus systems in manufacturing field, there is a great need for extending their uploaded signals data capacity with high accuracy. A state estimator function block is designed, simulated and analyzed using Matlab/Simulink program to be adapted with a foundation fieldbus of any dynamic system. The designed block contains an adapted PI controller to eliminate the estimated error and ensures a smooth stable block response. The adapted controller block is added in different locations to eliminate the error results from the estate estimator. The controller parameters are changed according to the system input signal to ensure over-damped estimated output signal with zero error. Artificial Neural Network (ANN) technique is utilized in controller parameters determination. The developed intelligent controlled state estimator function block is tested on a 3rd order dynamic system, and the results presents satisfying output. The block design and optimization using Matlab/Simulink and is implemented to an impeded system.