Hardware reference guide

Modbus Plus NOM
288
35013379 11/2011
Adding a New Node to the Network
If a new node is added to an existing network in order to extend the network (at the
end of any configuration), then a new node may be connected first by fiber cable and
then hot-swapped to the backplane to avoid errors to the existing network.
If a new mode is added to the middle of the network, the fiber optic cables need to
be disconnected from one side of the existing NOM252 module and connected to
port 1 or 2 of a new node. Additional fiber optic cable then needs to be connected to
the second port of the new NOM252 and to the next NOM252 in the network, the
new NOM252 then has to be hot-swapped to the backplane.
Repairing the Break in the Cable
Because the NOM25200 will stop transmitting in the direction from which it is not
receiving the signal, the replacement of a broken fiber optic cable and the
reconnection of it will not re-establish communication over that segment. The hot
swap of only one NOM252 at the repaired connections is required to complete the
connection.
NOTE: The break of any fiber connectors or fiber optic cables is the equivalent to
the break of the trunk cable in a Modbus Plus network on copper.
For the self healing ring configuration, the repair of the first break in the fiber optic
network has to be scheduled to the time when one of the units on either side of the
repaired break can be hot-swapped without creating the problem by disconnecting
the node.
NOTE: Self healing configurations are not considered redundant networks. High
system availability can be achieved with redundant networks.
WARNING
Hot Swapping Restriction
Modules may be hot swapped when the area is known to be non-hazardous. Do
not hot swap modules in a Class 1, Division 2 environment.
Failure to follow these instructions can result in death, serious injury, or
equipment damage.