93
Step 1: Evaluating the Configuration with Graphs
Section 3-4
Flat Cable
3-4-1
Simple Evaluation of Power Supply Location from a Graph
Check items 1 to 3 listed below for all of the nodes located in the same direc-
tion from the power supply. (If power is supplied in two directions, check these
3 items for all of the nodes in each direction.)
1,2,3...
1.
Calculate the total current consumption (I
A
) of all the nodes to which com-
munications power is to be supplied in one direction.
2.
Refer to the graph to find the maximum current flow (I
B
) allowed in the ca-
ble based on the type of cable being used (thick or thin) and the distance
from the power supply to the end of the trunk line.
3.
Compare the values (I
A
and I
B
) found in steps 1 and 2 above. If I
A
≤
I
B
, the
power supply specifications are met and power can be supplied properly
to all nodes.
Note
Be sure to refer to the correct graph because the maximum current
flow is different for thick and thin cables.
3-4-2
Modifying the Configuration
If the graph indicates that power cannot be supplied properly in one direction
(I
A
> I
B
), use the following procedure to modify the communications power
supply configuration.
• Move the communications power supply towards the center of the net-
work so that there are nodes to both sides of it.
• If there are already nodes on both sides of the power supply, move the
power supply in the direction that requires the higher current.
• If thin cable is being used, replace it with thick cable.
If power still cannot be supplied properly in one direction (I
A
> I
B
) after making
the changes listed above, proceed to Step 2 and calculate the actual current
requirements based on each node’s position in the network and its current
consumption.
Distance (m) 0
20
40
80
100
140
200
260
300
Maximum
current (A)
5.00 5.00 5.00 2.75 2.21 1.58 1.11 0.85 0.74
6
5
4
3
2
1
0
0 20 40 60 80 100 120 140 160 180 200 220 240 260 280 300
Max
imum
c
u
rrent
(A
)
Distance (m)
Summary of Contents for DEVICENET -
Page 1: ...DeviceNet Cat No W267 E1 11 OPERATION MANUAL...
Page 2: ...DeviceNet Operation Manual Revised April 2008...
Page 3: ...iv...
Page 5: ...vi...
Page 7: ...viii...
Page 9: ...x...
Page 13: ...xiv...
Page 41: ...20 Basic Operating Procedures Section 1 4...
Page 107: ...86 Operational Checklist Section 2 6...
Page 123: ...102 Step 3 Splitting the System into Multiple Power Supplies Section 3 6...
Page 161: ...140 Index...