Wiring I/O Units
Section 3-5
Inductive Load Surge
Suppressor
When an inductive load is connected to an I/O Unit, connect a surge suppressor
or diode in parallel with the load, as shown in the following diagram. The diode
will adsorb the back electromagnetic field generated by the load.
IN
L
Diode
DC input
COM
L
OUT
Relay Output Unit
riac Output Unit
Surge suppressor
COM
T
L
OUT
+
Relay Output Unit
ransistor Output Unit
Diode
T
COM
where for the surge suppressor
,
Resistor: 50
W
Capacitor:0.47 F
Voltage: 200 V
and the diode,
Breakdown voltage: at least 3 times load voltage
Mean rectification current: 1 A
Input Units
Voltage Inputs
Do not wire voltage inputs as shown on the left below.
V
oltage output
V
oltage output
Sensor
power
supply
+
COM (+)
+
IN DC input
Output
Output
0 V
IN DC input
COM (–)
Sensor
power
supply
0
V
Incorrect
Correct
Input Leakage Current
When two-wire sensors, such as photoelectric sensors, proximity sensors or
limit switches with indicators are connected to the PC as input devices, the input
bit may be turned ON erroneously by leakage current. In order to prevent this,
connect a bleeder resistor across the input to reduce the input impedance.
Input
power
supply
Bleeder
PC
R
resistor
Sensor
63
OMRON [ OMRON ELECTRONICS LLC ]
