Omron OMNUC W Series Manual page 107

6 DeviceNet Communications
6.3.1 Providing the Communications Power Supply
Distance (m)
current
Max. (A)
Max. current (A)
6
Distance (m)
current
Max.
Max. current (A)
Step 1: Determining the Best Location for the Power Supply
from a Graph
A voltage drop occurs when a current flows through a DeviceNet special cable. The longer
the communications cable and the greater the current, the greater the voltage drop. The com-
munications power supply at each node must be 11 V DC or more. To ensure this, the rela-
tionship is plotted as shown in the graph below to find the maximum current that easily
satisfies the voltage of the communications power supply at different trunk line lengths even
if there is a voltage drop due to cable resistance.
Thick Cable
0 25 50 100
8.00 8.00 5.42 2.93
8
7
6
5
4
3
2
1
0
0 50 100
Thin Cable
0 10 20
3.00 3.00 3.00
(A)
3
2
1
0
0 10 20
150 200 250 300
2.01 1.53 1.23 1.03
150 200 250 300
Distance (m)
30 40 50 60
2.06 1.57 1.26 1.06
30 40 50 60
Distance (m)
6-10
350 400 450 500
0.89 0.78 0.69 0.63
350 400 450 500
70 80 90 100
0.91 0.80 0.71 0.64
70 80 90 100