Omron NX-ID - Precautions When Wiring to the Output Units

4 Installation and Wiring
4 - 52
NX-series Digital I/O Unit User’s Manual (W521)
If a load connected to the output terminals is short-circuited, output components and printed circuit
boards may be damaged. To guard against this, use the NX Units with load short-circuit protection.
When using the NX Units without load short-circuit protection, incorporate a protective fuse in the exter-
nal circuit. Use a fuse with a capacity of around twice the rated output.
When connecting a transistor to an output device with a high inrush current (such as an incandescent
lamp), steps must be taken to avoid damage to the output transistor.
Use either of the following methods to reduce the inrush current.
z Countermeasure 1
Draw about 1/3 of the current consumed by the load.
When I/O power is supplied from the NX bus, the method is as shown in the following figure.
When I/O power is supplied from an external source, the method is as shown in the following figure.
4-4-2 Precautions when Wiring to the Output Units
Output Short-circuit Protection
Inrush Current
IOG
IOV
IOG
IOV
Transistor Output Unit
OUT
IOG
IOV
IOG
IOV
OUT
NPN type PNP type
L
L
Communications
Coupler Unit or
Additional I/O Power
Supply Unit
Transistor Output Unit
Communications
Coupler Unit or
Additional I/O Power
Supply Unit
OUT
COM
R
Transistor Output Unit
NPN type PNP type
L
+
OUT
COM
R
Transistor Output Unit
L
+