i want to know the benefit of using Filtering parameter in A/D configuration in addition of smoothing output signal, and is that important to use it. and i would like to know how to choose the optimum value for it
The filtering parameter in the A/D configuration allows some digital filtering to occur directly on the input to the line. If you are already performing smoothing on your output signal then it is not necessary to use the A/D filter.
Choosing an optimum value is dependent on the characteristics of the signal you are attempting to capture such as bandwidth. The filter equation can be found on page 13 of the SensRcore Messaging and Usage document, which can be found here.