Precautions On Locating The I/O Power Supply - Omron CJ Series Operation Manual

4-4-6 Precautions on Locating the I/O Power Supply

When building a system, the supply methods for communications power and I/O power must be consid-
ered. Not only hardware, such as selecting the power supplies and cables based on allowable currents
and voltage drop, be considered, but also system operation for power supply errors, costs, and other
software issues must be considered when studying power supply methods.
Supplying I/O Power from One Source
When supplying I/O power to the entire system from one source, the power consumed by each devices
and the loads must be considered. Select the cables so that the power supply voltage for the last Slave
Unit and load will be within the allowable range.
Also, give proper consideration to the power supply capacity and be sure the total line current is within
the allowable current range of the cable.
The following measures can be considered to keep the voltage drop within the allowable range when
supplying power from one power supply.
• Increase the thickness of the cables.
• Increase the output voltage of the power supply.
• Shorting the wiring.
• Locate the power supply in the middle of the network.
1
Power supply
(24 VDC)
Supplying I/O Power from Multiple Sources
Supplying I/O power from multiple power supplies instead of from one power supply enables reducing
the line current, reducing the voltage drop, and decreasing the size of the cable. Using multiple power
supplies should also be considered to increase system safety when power supply errors occur.
Power supply
(24 VDC)
CJ-series CompoNet Master Unit Operation Manual for NJ-series CPU Unit (Cat. No. W493)
Slave Unit Slave Unit
Load
2
I
I
1
2
Slave Unit Slave Unit
CP
Slave Unit
Load
Load
3 4
I
I
3 4
If a stable power supply voltage cannot
Power supply
supplied to the end load, place the power
(24 VDC)
supply in the middle of the network.
Slave Unit Slave Unit
4 Installation and Wiring
Slave Unit
Load
Design the wiring so that a
stable power supply voltage is
supplied to the end load.
CP
Power supply
(24 VDC)
4
4-43