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Appendix E
E.1 Basic Network Layout
Multi-drop RS-485 implies that there are two main wires in an segment.
The connected modules tap from these two lines with so called drop
cables. Thus all connections are parallel and connecting or
disconnecting of a node doesn't affect the network as a whole. Since
ADAM modules use the RS-485 standard, and use an ASCII-based
commands set, they can connect and communicate with all ASCII-
based computers and terminals. The basic layouts that can be used for
an RS-485 network are:
Daisychain
The last module of a segment is a repeater. It is directly connected to
the main-wires thereby ending the first segment and starting the next
segment. Up to 32 addressable modules can be diasychained. This
limitation is a physical one. When using more modules per segment the
IC driver current rapidly decreases, causing communication errors.
Totally the network can hold up to 256 addressable modules. The
limitation for this number is the two number hexadecimal address codes
that know 256 combinations. The ADAM converter, ADAM repeaters
and the host computer are non addressable units and therefore are not
included in these numbers.
Figure E-1 Daisychaining
Appendix E RS-485 Network E-3
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