YASKAWA DX200 Instructions Manual page 64

JARCR-XFB01B Board
for DeviceNet
7 Connections for DeviceNet Communications
7.1 Location of Communication Power Supply
4. Calculation with Actual Values
If the result of the simplified calculation based on the graph still does
not satisfy the conditions, check by detailed calculations using the
following equation.
(1) Equation
I) When a communications power supply and an internal circuit
power supply are separate
Check the distance between the power supply and each node
in addition to the current consumption for the communications
unit of each node.
If these values satisfy the following equation, sufficient power
can be supplied to the node.
However, the current must not exceed the maximum allowable
current to the cable, 8 A for a thick cable and 3 A for a thin
cable.
Equation
Ln : Distance between the power supply and a node
(excluding the length of the drop line)
Rc : Maximum resistance of the cable (0.015 /m for a thick
cable, 0.069 /m for a thin cable)
Nt : Number of adapters between the power supply and a
node
In : Current consumption required for the communications
unit of node
0.005= Contact resistance value of an adapter
7-7
 [(Ln Rc + Nt  0.005) In]  4.65V
HW1481973
165626-1CD
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