Advantech ADAM 4100 User Manual page 140

RS-485 Network
Star Layout
In this scheme, the repeaters are connected to drop-down cables from
the main wires with modules connected after it. A tree structure is
formed as the result. However, this scheme is not recommended when
long lines are implemented since it will cause a serious amount of
signal distortion due to a signal reflection at each end of the lines.
Random
This is a combination of daisychain and hierarchical structure
E-4 ADAM 4100 Series User's Manual
Figure E-2 Star structure
Figure E-3 Random structure