Consideration On Disposition Of A Communication Power Supply; Figure 6-19 Current Capacity By Main Line Thickness - Hitachi S10mini LQS070 Hardware Manual

6.1.5

Consideration on disposition of a communication power supply

In the DeviceNet network, each node is supplied power from a 5-wire communication cable
through a communication connector. Therefore, check whether each node can be supplied
power from a planned power supply disposition independently of the cable length restriction
(see Section 6.1.4) when constructing the network.
Calculate the following in advance before consideration:
• Current consumption (the amount of required current) of each node
• Type (Thick or Thin) and length of each communication cable determined in Section
6.1.4.
First of all, confirm the total required amount of current of all the nodes is within the
capacity of the communication power supply. If it exceeds the capacity, either replace the
power supply with one that has a larger current capacity or separate the system into two or
more parts and supply power from multiple power sources .
Secondly, check the maximum current capacity of cables. The maximum current capacity
if the main line cable is 8A (for a thick cable) or 3A (for a thin cable). Therefore, a single
communication power supply can feed a current up to 16 A (for a thick main line) or 6 A
(for a thin main line) as shown below.
8 A
Main line
If the total amount currents required by all the nodes exceeds the maximum capacity of 6A,
thin cable would not work no matter where it is connected. Consider using thick cables
instead of the thin ones.
<Thick main line>
8 A
Power
tap
Main line
16 A
Communication
power supply
24 VDC

Figure 6-19 Current Capacity by Main Line Thickness

<Thin main line>
3 A
Power
tap
Main line
Communication
power supply
24 VDC
− 49 −
6 CABLING
3 A
Main line
6 A