Omron NX1P2 series User Manual page 121

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 Sup-
ply 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
Current consumption from I/O
power supply
Current consumption between
the NX Units and the connected
external devices
 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
below.
Configuration and Conditions
Additional I/O Power
Supply Unit
NX-PF0730
I/O
power
supply
(24 VDC)
I/O power supply voltage
Inputs
Outputs
I/O power is supplied to the NX-ID3317 and NX-OD3121 from the NX bus.
NX-series NX1P2 CPU Unit Hardware User's Manual (W578)
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.
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.
Digital Input Digital Output
Unit Unit
NX-ID3317 NX-OD3121
Connected
Connected
output
input
devices
devices
(loads)
Item
Number of inputs used (that turn ON simultaneously)
Current consumption of connected input devices
Number of outputs (that turn ON simultaneously)
Load current of connected loads
Current consumption of connected output devices
4 Designing the Power Supply System
Description
End Cover
Condition
24 VDC
4 points
50 mA/point
4 points
125 mA/point
50 mA/point
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