Siemens Simatic box pc 627b Operating Instructions Manual page 29

Additional permissible PC mounting positions according to UL508/CSA 22.2 No. 142
An inclination of ±15° is allowed in this mounting position. An external fire protection casing
is required.
Position 5 (ports facing down)
CD/DVD drive cannot be operated.
Note
CD/DVD and flopply drives cannot be operated in this position. The CD drawer opens
upward or downward which can lead to mechanical damages in the drawer mechanism.
SIMATIC Box PC 627
Operating Instructions, Release 05/2006, A5E00362052-03
4.5 Permitted mounting positions
Position 6 (ports facing above)
CD/DVD drive cannot be operated.
Application Planning
4-5