Mitsubishi Electric QJ71DN91 User Manual page 104

5 SETUP AND PREPARATION
Terminating
resistor
Master node
1.1A
Terminating
resistor
Master node
1.1A
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(3) When the network power supply current capacity is insufficient
In the case where the network power supply unit is connected to the following
network that uses thick cables:
Slave node Slave node
1.25A 0.5A
120m
Power supply distance on the left side = Power supply distance on the right side
= 120m
Total current capacity of the left side = 1.1A + 1.25A + 0.5A = 2.85A
Total current capacity of the right side = 0.25A + 0.25A + 0.85A = 1.35A
Max. current capacity available for thick cable length of 120m (See Table 5.4.) =
approx. 2.56A
(Straight-line approximation between 100m and 150m)
In this configuration, the current capacity on the left side is insufficient.
In this case, move the network power supply unit in the direction of insufficient
current capacity (to the left in the figure above).
Network power
supply unit
Slave node
1.25A
100m
Total power supply distance on the left side = 100m
Total power supply distance on the right side = 140m
Total current capacity of the left side = 1.1A + 1.25A = 2.35A
Total current capacity of the left side = 0.5A + 0.25A + 0.25A + 0.85A = 1.85A
Max. current capacity available for thick cable length of 100m (See Table 5.4.) =
approx. 2.93A
Max. current capacity available for thick cable length of 140m (See Table 5.4.) =
approx. 2.19A
(Straight-line approximation between 100m and 150m)
As a result of shifting the network power supply unit, it is able to supply power to
all nodes.
Network power
supply unit
Slave node
0.25A
Slave node Slave node
0.5A 0.25A
140m
MELSEC-Q
Slave node Slave node
0.25A 0.85A
120m
Slave node Slave node
0.25A 0.85A
Terminating
resistor
Terminating
resistor
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