Toshiba DeviceNet nv Series Instruction Manual page 47

(2) The optimal placement method for network power supply equipment determination
Follow these steps to determine the location of the network power supply.
Sum the network current consumed by each node on the network. Nodes that use network power as the
a)
operating power for the node, use the sum of both.
Measure the total length of the network.
b)
Determine based on type of the cable used for trunk line (thick cable or thin cable) and the total length of
c)
the network determined in step b), use Figure 3-5 or Figure 3-6 to determine the maximum current that
can be passed through the cable.
If the total current consumed by the network (step a) is smaller than the maximum current that can be
d)
passed through the cable (step c), power is supplied to all nodes from the network power supply located
at the end of the network. Can be supplied (= single power supply terminals connection).
If the total current consumed by the network (step a) is greater than the maximum current that can be
e)
passed through the cable (step c), place a network power supply near the center area of the network to
check whether power can be supplied to the node (= single power supply center connection).
If the network power cannot be supplied to all nodes with a single power supply central connection,
f)
increase the number of network power supply units.
(3) Single power termination connection
In this part, an example is shown in which a network power supply is placed at the end of a trunk line (using
thick cables) with a total length of 200 m. The current consumption for each node is shown in the figure below.
V+
Power
Tap
V-
Network
power supply
Figure 3-7 Example of single power supply termination connection
Node Node
1 2
0.1A
0.15A
200m
a) Total current consumption = 0.1 A + 0.15 A + 0.05 A + 0.25 A + 0.1 A = 0.65 A
b) Total length of the power supply = 200 m
c) The maximum current that can be passed through the cable
from Figure 3-5 = 1.53 A
d) Since total current consumption < maximum current, power can be supplied
to all nodes with a single power supply terminal connection
e) Use a network power supply with a rated current of 0.65A or more.
(Select a product with sufficient margin in consideration of usage condition, etc.)
Unified Controller nv Series DeviceNet Module DN611B Instruction Manual
3.6 Network power and ground
Node
Node
3
4
0.05A 0.25A
Node
5
0.1A
31