Omron NX-ECC201

5 - 13
5 Designing the Power Supply System
NX-series EtherCAT Coupler Unit User’s Manual (W519)
5-3 Designing the I/O Power Supply System
5
5-3-2 Designing the I/O Power Supply from the NX Bus
Voltage drop occurs in the EtherCAT Slave Terminal due to the contact resistance at the points where
Units are connected to each other. Design the I/O power supply system to maintain the voltage specifi-
cations of the NX Unit I/O circuits and connected external devices even if the voltage of the I/O power
supply drops.
As shown in the following table, the voltage drop per Unit depends on the total current consumption
from the I/O power supply.
Here, the following Unit configuration example is used to show how to calculate the I/O power that is
supplied by the EtherCAT Coupler Unit. The same method can be used to calculate the I/O power sup-
ply from an Additional I/O Power Supply Unit.
*1. The current consumption of the EtherCAT Coupler Unit is not actually 0 A. However, a value of 0 A is used in
this calculation example.
In actual calculations, use the current consumption from the I/O power supply that is given elsewhere in this
manual.
 Outline
Find the I/O power supply voltage of the NX Unit that is the farthest from the EtherCAT Coupler Unit.
In this example, the I/O power supply voltage of Unit (7) is found.
 Conditions
Assume that an I/O power supply voltage of 24.00 VDC is supplied to the I/O power supply terminals
on the EtherCAT Coupler Unit.
Calculating the Voltage Drop in the I/O Power Supply
Total current consumption from the I/O
power supply
Voltage drop per Unit
4 A 0.08 V
3 A 0.06 V
2 A 0.04 V
1 A 0.02 V
Example:
(1) (2) (2) (4) (5) (6) (7)
To external
devices
To external
devices
I/O power
supply
(24 VDC)
Power Consumption of Individual Units
(1): 0 A
*1
(Supplied from the NX bus.)
(2) and (3): 1.5 A each (Supplied from the NX bus.)
(4) and (5): 0 A (Supplied from external source.)
(6) and (7): 0.5 A each (Supplied from the NX bus.)
● Total current consumption from the Units
that are supplied I/O power from the
EtherCAT Coupler Unit (total for (1) to
(7) = 4 A)
● Units that are supplied I/O
power from the Additional I/O
Power Supply Unit
Additional I/O Power Supply Unit
EtherCAT Coupler Unit
NX Units
End Cover
To external
devices
I/O power
supply
(24 VDC)