Advantech ADAM-5510/P31, Manual

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ADAM-5510/P31 E-3
Appendix E
E.1 Basic Network Layout
Multi-drop RS-485 implies that there are two main wires in a segment.
The connected systems tap from these two lines with so called drop
cables. Thus all connections are parallel and connecting or discon-
necting of a node doesn’t affect the network as a whole. Since
ADAM-5510/P31 systems use the RS-485 standard, they can connect
and communicate with the host PC. 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 systems can be daisychained . This
limitation is a physical one. When using more systems per segment the
IC driver current rapidly decreases, causing communication errors. In
total, the network can hold up to 64 addressable systems. The limita-
tion on this number is the two-character hexadecimal address code that
can address 64 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
Coverter
RS232/RS485
RS-232
RS-485
Repeater
1
Segment 2 Segment 1
1 2 N 1