Omron OMNUC W Series Manual page 50

4.5 Connection and Wiring of the DeviceNet Communications Connector
Maximum Lengths of DeviceNet Communications Lines
Baud Rate Maximum Network Length (m)
(kbit/s)
Thick Cable
500 100
250 250
125 500
* 1. Thick cable (5-wire): DCA2-5C10 (100 m)
* 2. Thin cable (5-wire): DCA1-5C10 (100 m)
Maximum Network Length
The maximum network length is longest of the following:
• Distance between the two most distant nodes
• Distance between the Terminating Resistors
There are two types of cables for special DeviceNet cables: Thick cables and thin cables.
The maximum length of a network depends on the type of cable that is used, as shown in the
above table. Use the cables within the restrictions given for them. (The signal voltage atten-
uation is affected by the cable thickness, and thus the maximum length is different.)
If both types of cable are combined in the same network, the following restrictions apply.
Baud Rate (kbit/s)
500
Length of the thick cable + Length of thin cable
250
Length of the thick cable + 2.5
125
Length of the thick cable + 5.0
Drop Line Lengths
A drop line length is measured from the point in the trunk line where the original branch was
made to the end of the branch. The maximum length of a drop line is 6 m. It is possible to
make more branches from a drop line, but the total length must be added to the drop line
length from the first branch from the trunk line to the end of the last drop line.
Total Drop Line Length
A total drop line length is the total sum length of all the drop lines used for the communica-
tions line. It does not include the length of the trunk line. The standard for the total drop line
length varies with the baud rate; refer to the table in Maximum Lengths of DeviceNet Com-
munications Lines on page 4-19.
4-19
Maximum Drop
Line Length (m)
*1 *2
Thin Cable
100 6
100 6
100 6
Maximum Network Length
×
Length of thin cable
×
Length of thin cable
Maximum Total Drop
Line Length (m)
39
78
156
≤
100 m
≤
250 m
≤
500 m
4