Omron CJ2-CPU User Manual

5 Designing the Power Supply System
5 - 12
NX-series EtherNet/IP Coupler Unit User’s Manual (W536)
 Calculation Examples
Examples of calculating the current consumption from the I/O power supply are given below for a
Digital Input Unit and Digital Output Unit.
Voltage drop occurs in the EtherNet/IP 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. However, the total current consumption from the I/O power supply must not
exceed the maximum I/O power supply current of the Unit that supplies the I/O power.
Here, the following Unit configuration example is used to show how to calculate the I/O power that is
supplied by the EtherNet/IP Coupler Unit. The same method can be used to calculate the I/O power
supply from an Additional I/O Power Supply Unit.
Current consumption between
the NX Units and the connected
external devices
This is the current that is consumed between the NX Units and the con-
nected external devices.
For example, this is the current consumed by a Digital Input Unit to supply
power to photoelectric sensors or to turn ON the input circuits in the Digital
Input Unit.
The current consumption depends on the type of I/O circuit in the NX Unit,
the number of I/O points that are used, and the current consumption of the
connected external device. It must be calculated for each NX Unit.
Current consumption of Digital
Input Unit
=
Current consumption from I/O power supply + (Input current × Number
of inputs used) + Total current consumption of connected input devices
Current consumption of Digital
Output Unit
=
Current consumption from I/O power supply + Total load current of con-
nected loads + Total current consumption of connected output devices
Calculating the Voltage Drop in the I/O Power Supply
Total current consumption from the I/O power supply Voltage drop per Unit
10 A 0.20 V
8 A 0.16 V
6 A 0.12 V
4 A 0.08 V
3 A 0.06 V
2 A 0.04 V
1 A 0.02 V
Current consumption item Description

Omron CJ2-CPU Specifications

General

Brand	Omron
Model	CJ2-CPU
Category	Controller
Language	English