Siemens SIMATIC ET 200SP HA System Manual page 49

The shield terminal connects the cable shield to the mounting rail via the Ex BaseUnit.
You can find additional information on this in the section "Connecting cable shields (Page 65)".
Recommendation:
Application in an environment with interference:
• Use shielded cables for analog modules.
• Use shield terminals to connect the cable shield to functional grounding.
Observe the required measures for explosion protection.
Modules for devices in a hazardous area
System Manual, 04/2021, A5E50165138-AA
Plant planning
4.6 Power supply and potential ratios
49