4
model 2000 DeviceNet Module Manual (DN611/DN611A)
Chapter 1 Overview of the Devicenet Module
1
1.2.2
Trunk line/drop line and maximum cable length
The DeviceNet specifications cover the thick cable and the thin cable. For the details,
see DeviceNet Volume I. Cables conforming with the thick cable and thin cable
standards are now commercially available. Buy ones which meet the configuration of
your network (Details are explained in 3.6 Network Components).
(1) Trunk Line
A DeviceNet trunk line consists of a thick cable or a thin cable (mixed use is also
possible). The thin cable is easy to install because it is more flexible than the thick
cable. The thick cable, however, allows longer network cabling than the thin cable.
The maximum trunk line length varies depending on the type of cable used and the
communication rate of the network. For details, see (3) Maximum Network Length.
(2) Drop Line
A DeviceNet drop line consists of a thin Cable. Table 1-1 shows the length of drop
lines and the total length per network. Nodes can be arranged on drop lines in a
short drop line configuration, multi-drop configuration, or branch configuration.
Figure 1-4 shows how to calculate the drop line length and the total length for each of
these configurations.
Individual drop line length : a <= 6m, b <= 6m, c <= 6m, d <= 6m
(Short drop line configuration)
e <= 6m (Multi-drop configuration)
f
+
g <= 6m, f
+
h <= 6m, f
+
i <= 6m (Branch configuration)
Total extension of drop lines : a
+
b
+
c
+
d
+
e
+
f
+
g
+
h
+
i
Figure 1-4 Example of Calculating Drop Line Length
Table 1-1 Maximum Drop Line Length
Communication Rate
Drop Line
Total Extension per Network
125kbps
156m
250kbps
6m
78m
500kbps
39m
Node 45
Node 5
Node 0
Node 60
Node 55
Node 50
Node 40
Node 30
Node 35
Node
25
Node
20
Node
15
Node
10
Tap
Terminator
Tap
Multiport tap
Branch configuration
Short drop line configuration
Multidrop
configuration
Terminator
i
h
g
f
e
d
c
b
a
Tap
Multiport tap
No drop line configuration