
B-64044EN/01 CONNECTION 1.CONNECTING THE DeviceNet
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Rough calculation by the graph
Check items (1) to (3) for each of the nodes placed on the same side of
the power supply.
When nodes are placed on both sides of the power supply, check the
items for each side.
(1) For each side, calculate the sum of power consumption (A) of the
nodes placed on the side.
(2) Obtain the maximum amount of current (B) that can pass through
a cable based on the type of the cable (thin-wire or thick-wire
cable) and the distance between the power supply and the farthest
end of the main line.
(3) If the sum of power consumption (A) calculated in (1) is less
than or equal to the maximum amount of current (B) obtained
from the graph in (2) (A ≤ B), the power supply conditions are
satisfied for all nodes.
NOTE
The graph referenced depends on the type of a
cable (thick-wire or thin-wire cable) used as the
main line.
Action
If the sum of power consumption (A) calculated in (1) is greater than
the maximum amount of current (B) obtained from the graph in (2) (A
> B), try to take the following actions.
- Move the power supply in the central direction so that it is placed
in the middle of nodes.
- If nodes are already placed on both sides of the power supply,
move the power supply in the direction where larger amount of
current is required.
- When using a thin-wire cable, replace it with a thick-wire cable.
Even after taking any of the above actions, A > B is satisfied, change
the configuration using the expression that takes the actual node
layout into consideration.
- When the power supply is placed at the end (example 1)
The following provides an example of placing the power supply for
communication at the end of a network using a thick-wire cable
(THICK cable) with a total extended length of 200 m for supplying
power.
Power consumption for each node is assumed as shown below.
Terminator
Node Node
Power supply for
communication
erminator
Power tap
NodeNode
200m
Main cable (5-wire cable)
0.25A 0.05A0.25A0.1A
Total length of the power supply line = 200 m
Total power consumption = 0.1 A+0.25 A+0.05 A+0.25 A=0.65
A