
1.CONNECTING THE DeviceNet CONNECTION B-64044EN/01
- 60 -
When nodes are places on both sides of the power supply (sample
configuration 2)
Terminator
Power supply for
communication
Terminator
Node
Power
tap
50mA
Node
5 nodes
Node
40mA
40mA
Node
30mA
Node
8
nodes
Node
30mA
30mA
Node
50mA
Node
10 nodes
Node
50mA
50mA
20m 10m
30m
<Group 1>
50mA+40mA
×
5=250mA
<Group 2>
30mA
×
8=240mA
<Group 3>
50mA
×
10=500mA
Power supply for
communication
Branch line:
thin-wire cable
Main cable:
thick-wire
System 1 System 2
Calculate the voltage drop for each group for each system.
Group 1 in system 1: (20×0.015+1×0.005)×0.25=0.07625 V
Group 2 in system 2: (10×0.015+1×0.005)×0.24=0.0372V
Group 3 in system 2: (30×0.015+2×0.005)×0.50=0.23V
Voltage drop in system 1 = 0.07625 V ≤ 4.65 V
Sum of voltage drops in system 2 = 0.0372 V+0.23=0.2672 V ≤ 4.65V
Therefore, the conditional expression is satisfied in both systems.
1.7.5 Method of Supplying Power Using Multiple Power Systems
When the conditions cannot be satisfied even if calculation is
performed with the expression, separate the power system by using
multiple power supplies for communication.
Method of separating the power system
Since multiple power supplies are present, use the power tap for each
power supply. The power tap is not supplied by FANUC, so
purchase the power tap that conforms to the DeviceNet standards from
other companies.
The internal circuit of the power tap is shown below.
V+
CAN H
Power tap
Shotkey
diode
Shield
CAN L
V-
V+
CAN H
Shield
CAN L
V-
V- V+
5-wire cable
B side
Fuse A Fuse B
Ground
terminal
Power supply unit
5-wire cable
side
To disconnect the power system on the cable A side, remove fuse A.
To disconnect the power system on the cable B side, remove fuse B.