TIDA-01401: Does the shield of the RS485 cable need grounding?

Part Number:TIDA-01401

Hi TI Engineer：

       I have two questions.

       1.In many circuit systems, a parallel scheme of resistors and capacitors is used to connect the external earth ground with the internal GND.In this way, the DC is isolated, while the AC is a low impedance.What are the benefits of doing this for EFT testing?How to select resistance value and capacitance value?Panasonic servo driver, this capacitor value is 0.1uF.

       2.In the EFT test mentioned in the paper, does the RS485 cable shield connect the earth?In that case, the RS485 cable shield should be single ended or double ended grounding,and Why?

thank  you