Omron OMNUC W R88A-NCW152-DRT, Manual

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4.5 Connection and Wiring of the DeviceNet Communications Connector
4-19
4
Maximum Lengths of DeviceNet Communications Lines
* 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.
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 .
Baud Rate
(kbit/s)
Maximum Network Length (m) Maximum Drop
Line Length (m)
Maximum Total Drop
Line Length (m)
Thick Cable
*1
Thin Cable
*2
500 100 100 6 39
250 250 100 6 78
125 500 100 6 156
Baud Rate (kbit/s) Maximum Network Length
500
Length of the thick cable + Length of thin cable
≤
100 m
250
Length of the thick cable + 2.5
×
Length of thin cable
≤
250 m
125
Length of the thick cable + 5.0
×
Length of thin cable
≤
500 m