The shielding of the FDnet/C-NET detector line must never be used as a
secondary-side ground potential or connected to other shields. If shields are
connected, this can result in faults on the FDnet/C-NET detector line.
Terminals 15 and 16 are used exclusively for looping through the shields.
See also
Configuration as a collective detector line (GMT) [ 28]
Configuration as a contact input [ 33]
Configuration as a control line [ 35]