12 Issue
Number:
2
3.6 Maximum
Network
Length
The data rate that can be used depends mainly on the length of cable
that is being used in the network, so the physical layout of the network
must be considered during the network design stage of a project.
Data
Rate
(bits/sec)
125K 250K 500K
Max
Trunk
Distance
500m 250m 100m
Max
Drop
Length
6m 6m 6m
Cumulative Drop Length
156m
78m
39m
Number
of
Nodes
64 64 64
DeviceNet networks usually consist of a main terminated trunk cable
length, with a series of drop cable lengths (without termination) running
off the main trunk cable.
For a detailed description about the limitations and requirements for
installing a DeviceNet network, refer to Allen Bradley Publication
Number DN-6.7.2. (This document is available from the Allen Bradley
web site at “www.ab.com”.)
3.7 External
Power
Supply
An external is24V power supply is required to power the
transceiver circuits in the DeviceNet nodes. The physical location of the
ex24V power supply can be very important, particularly if the
network has several nodes that draw significant power from the supply.
The Unidrive DeviceNet interface is powered by the Unidrive internal
power supply. However, the ex24V power supply must be
connected to meet ODVA specifications. Each Unidrive DeviceNet
interface draws 5mA max from the external supply.
For detailed instructions on designing the layout of the network and
determining power supply requirements, Allen Bradley Publication
Number DN-6.7.2. (This document is available from the Allen Bradley
web site at “www.ab.com”.)
