Mitsubishi Electric A1SJ71DN91 User Manual page 62

5. SETTINGS AND PROCEDURES BEFORE OPERATION
Termination
resistance
Master station
1.1A
Termination
resistance
Master station
1.1A
(3) Remedy for Insufficient Network Power Supply Current Capacity
If the network power supply unit is connected to a thick-cable network, as shown below.
Slave station Slave station
1.25A 0.5A
120m
Power supply distance left of the network power supply unit = power supply distance right
of the network power supply unit = 120 m
Total current capacity to the left = 1.1 A + 1.25 A + 0.5 A = 2.85 A
Total current capacity to the right = 0.25 A + 0.25 A + 0.85 A = 1.35 A
Max. current capacity of 120 m of thick cable (from Table 5.1) = approx. 2.56 A
(Linearly interpolated between 100 m and 150 m.)
In this configuration, the current capacity to the left of the network power supply unit is
insufficient.
If this type of situation occurs, move the network power supply unit in the direction of
insufficient current capacity (to the left in the diagram above).
Network
power supply
unit
Slave station Slave station
1.25A
100m
Total power supply distance left of the network power supply unit = 100 m
Total power supply distance right of the network power supply unit = 140 m
Total current capacity to the left = 1.1 A + 1.25 A = 2.35 A
Total current capacity to the right = 0.5 A + 0.25 A + 0.25 A + 0.85 A = 1.85 A
Max. current capacity of 100 m of thick cable (from Table 5.1) = approx. 2.93 A
Max. current capacity of 140 m of thick cable (from Table 5.1) = approx. 2.19 A
(Linearly interpolated between 100 m and 150 m.)
As a result of shifting the network power supply unit in the direction of insuffi-cient current
capacity, it is able to supply power to all stations.
Network
power supply
unit
Slave station
0.25A
120m
Slave station
0.5A
0.25A
140m
−
5 9
MELSEC-A
Slave station Slave station
0.25A 0.85A
Slave station Slave station
0.25A 0.85A
Termination
resistance
Termination
resistance