Hardware reference guide

Modbus Plus NOM
302
35013379 02 October 2007
Fiber Optic
Configurations
The following represent four typical configurations that show the wide range of the
network architecture:
z Point-to-Point connection,
z Bus configuration,
z Tree and Star configurations,
z Self Healing Ring configuration.
Point-to-Point
Configuration
Point-to-point configuration (see the following figure) allows communication over the
distance of up to 3 km through harsh industrial environments. The following figure
shows the point-to-point configuration.
Bus
Configuration
This type of configuration is used when it is required to connect a number of fiber
nodes and can be used to increase the distance of a standard Modbus Plus network
by changing to a fiber medium. This kind of network allows the connection of up to
32 Quantum NOM252 nodes over the distance of 5 km.
The following illustrations show the NOM25200 module in a mixed fiber optic/twisted
pairs bus configuration network and a pure fiber optic bus configuration network.
Fiber Optic Cables
Node # 1 Node # 2
P/S P/SCPU CPUI/O I/ONOM NOM
Point-to-Point Configuration Example
Equipment Failure
The loss of a single node in this configuration disables the rest of the network. It is
suggested that the Self Healing Ring configuration be used to avoid this problem.
Failure to follow this instruction can result in injury or equipment damage.
WARNING
This document provided by Barr-Thorp Electric Co., Inc. 800-473-9123 www.barr-thorp.com