Omron C200HE-CPU11 Installation Manual page 83

Wiring
AC Input Units
Input Leakage Current
The circuit below should be used for I/O devices having a voltage output.
Voltage output
The circuit below should NOT be used for I/O devices having a voltage output.
Voltage output
Contact output
AC Switching
Prox-
imity
switch
main
circuit
Note When using Reed switch as the input contact for an AC Input Unit, keep the
allowable current to 1 A or greater. If Reed switches with smaller allowable cur-
rents are used, the contacts may fuse due to surge currents.
When two-wire sensors, such as photoelectric sensors, proximity sensors, or
limit switches with LEDs, are used, the input bit may be turned ON erroneously
by leakage current. In order to prevent this, connect a bleeder resistor across the
input as shown below.
Sensor
If the leakage current is less than 1.3 mA, there should be no problem. If the leak-
age current is greater than 1.3 mA, determine the resistance (R) and power rat-
ing (W) for the bleeder resistor using the following formulas.
+
Output
Sensor
0 V
Power
Supply
Sensor
+
Power
Supply
Output
0 V
Input
power
supply
Bleeder
resistor
Section 3-2
COM
IN DC Input Unit
IN DC Input Unit
COM
IN AC Input Unit
COM
IN AC Input Unit
COM
PC
R
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