Advantech ADAM-5511 Manual page 47

The ADAM-5511 system provides 4 slots for use with I/O modules.
The I/O slots are numbered 0 through 3, and the channel numbering of
any I/O module in any slot starts from 0. For example, the ADAM-5017
is an 8-channel analog input module. Its input channel numbering is 0
through 7.
The ADAM-5511 system can be installed on a panel or on a DIN rail.
Panel mounting
Mount the system on the panel horizontally to provide proper ventila-
tion. You cannot mount the system vertically, upside down or on a flat
horizontal surface. A standard #7 tating screw (4 mm diameter) should
be used.