Siemens SIMATIC NET PROFIBUS Owner's Manual page 324

Installing Network Components in Cubicles
Note
Regardless of the degree of protection of the casing, the electrical and optical
ports are always sensitive to
– mechanical damage
– damage caused by electrostatic contact discharge
– contamination by dust and fluids
Close unused ports with the supplied dust protection caps. Remove these caps
only immediately before connecting up the cables to the ports.
Standards
EN 60529:1991 Degrees of protection provided by casing (IP code) (IEC
60529:1989)
EN 60529:1989 Degrees of protection provided by enclosures (IP Code)
Further Literature
Klingberg, G.; Mähling, W.: Schaltschrank– und Gehäuse–Klimatisierung in der
Praxis mit EMV; Heidelberg 1998
E-4
PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000