Omron NX1P2 series

Calculating the Total Current Consumption from the I/O Power Sup-
ply
The total current consumption from the I/O power supply from the NX bus is the total of the following
current consumptions.
• The current consumption from the I/O power supply that is required for the Additional I/O Power
Supply Unit and for the NX Units that are connected to the Additional I/O Power Supply Unit
•
The current consumption between the NX Units and the connected external devices
Current consumption item Description
Current consumption from I/O power
supply
This is the current that is consumed by the internal circuits that operate on the I/O
power supply
.
Specific values are given in the user
’s manuals for individual Units.
Current consumption between the NX
Units and the connected external de-
vices
This is the current that is consumed between the NX Units and the connected exter-
nal 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 num-
ber of I/O points that are used, and the current consumption of the connected exter-
nal device. It must be calculated for each NX Unit.
l
Calculation Example of I/O Power Supply Capacity
An example of calculating the required power supply capacity of the I/O power supply is given be-
low.
Configuration and Conditions
I/O
power
supply
(24 VDC)
Additional I/O Power
Supply Unit
NX-PF0730
End Cover
Digital Input
Unit
NX-ID3317
Connected
input
devices
Digital Output
Unit
NX-OD3121
Connected
output
devices
(loads)
Item Condition
I/O power supply voltage 24 VDC
Inputs Number of inputs used (that turn ON simul-
taneously)
4 points
Current consumption of connected input de-
vices
50 mA/point
Outputs Number of outputs (that turn ON simultane-
ously)
4 points
Load current of connected loads 125 mA/point
Current consumption of connected output
devices
50 mA/point
I/O power is supplied to the NX-ID3317 and NX-OD3121 from the NX bus.
4 Designing the Power Supply System
4-16
NX-series NX1P2 CPU Unit Hardware User’s Manual (W578)