Rockwell Automation DeviceNet Media Design Installation Guide - Manual (Page 18)

Publication DNET-UM072C-EN-P - July 2004
1-8 Get Started
In most cases, the maximum distance should be the measurement between
terminating resistors. However, if the distance from a trunk line tap to the
farthest device connected to the trunk line is greater than the distance from the
tap to the nearest terminating resistor (TR), then you must include the drop line
length as part of the cable length.
41647
TR
drop
If the distance from the TR to the last
tap is greater than the distance of
the drop, then measure from the TR.
3m (9.843 ft)
5m (16.405 ft)
drop
TR
3m (9.843 ft)
1m (3.281 ft)
Measure both drops and across the trunk.
tap
3m (9.843 ft)
TR tap tap tap tap
5m (16.405 ft)
drop
Always use the longest distance
between any 2 nodes of the network.
Measure the distance between the terminating resistors.
TR tap tap tap
D
D
tap
D D
D
D
If the distance from
the TR to the last tap
is less than the
distance of the drop,
measure from the
device.
D
D
D
D
D D
D
TIP
To extend the length of your network and
allow longer drop line lengths, you can
purchase a bus extender or wireless DeviceNet
modem from various vendors, such as Western
Reserve Controls, one of Rockwell
Automation’s Encompass partners. Contact
your Rockwell Automation representative for
details.