Omron DEVICENET -, Руководство по эксплуатации

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35
Network Configuration Section 2-2
• DeviceNet Cable
A Simple Way to Reduce
Total Branch Line Length It can be time-consuming to calculate the total branch line length and fairly dif-
ficult to meet the conditions that individual branch lines do not exceed 6 m
and the total branch line length does not exceed 39 m (with a baud rate of
500 kbps.) A common cause of long branch lines and excessive total branch
line length is using a straight trunk line, as shown in the following diagram.
The branch line lengths can be reduced significantly by redirecting the trunk
line at each node rather than using a straight trunk line. While this configura-
tion reduces branch line lengths, it will increase the maximum network length
(distance between the terminators or the nodes that are farthest apart). Verify
Line Cable type Maximum current capacity
Trunk Thick cable 8 A
Thin cable 3 A
Flat cable 5 A
Branch Thick or thin cable 0.75 to 3 A
The current capacity (A) of a branch line is 4.57/L (up
to 3 A) where L is the length (m) of the branch line.
Terminator Terminator
PLC Master
Branch
line
Network configuration
with a straight trunk line
Branch
line
Branch
line Branch
lines
too long
Branch line
Trunk line
Trunk line
Branch line
Branch line
T-branch Tap