Advantech Data Acquisition Modules ADAM 4000 - Manual (Page 407)

RS-485 Network
E-4 ADAM 4000 Series User’s Manual
Star Layout
In this scheme the repeaters are connected to drop-down cables from
the main wires of the first segment. A tree structure is the result. This
scheme is not recommended when using long lines since it will cause a
serious amount of signal distortion due to a signal reflection in a several
line endings.
Figure E-2 Star Structure
Random
This is a combination of daisychain and hierarchical structure
Figure E-3 Random Structure