Installation guide

12 Introducing the Modbus Plus Network
890 USE 100 00
Note: The address exchange can cause a momentary delay in
communication with the new primary unit while it assumes its place
in the network token rotation sequence. This can be a significant
factor in the timing of processes using redundant controllers. The
application should provide retry capabilities in the other nodes to
cover this time.
1.5.2 Network Option Modules
The Network Option Module (NOM) mounts in the backplane with the
controller. It allows the user application program, running in the
controller, to communicate with an additional Modbus Plus network.
The additional network can be configured with controllers, other
NOMs, Distributed I/O nodes, or a combination of these devices. One
or two NOMs can be mounted in the controller’s housing. Power is
taken from the power supply module which must also be installed in
the housing.
Network Option Modules are available for single-cable and dual-cable
network layouts. Contact your Modicon distributor for information
about models and part numbers.
Modbus
Connector
Modbus Plus
Connector
Channel A
Modbus Plus
Connector
Channel B
(Cover Open)
NOTENOTE
Network Option Modules are available for either
single-cable or dual-cable network layouts.
The dual-cable model is shown.
Modbus Plus
Address Switches
(on rear)
Figure 8 Network Option Module