Omron SYSMAC C200H Installation Manual page 58

I/O Connections
Two-wire sensor
V :
CC
V :
ON
I :
ON
I :
OFF
R :
IN
Input Leakage Current
Output Leakage Current
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x I
I
OFF leak
Refer to the information on input and output leakage current shown below.
The value of I depends on the Unit used. For Input Units that have an unspe-
OFF
cified OFF current, however, the value of I
V
R
V
CC
Power supply voltage V
PC ON voltage I
PC OFF current I
PC OFF current R:
PC input impedance
When two-wire sensors, such as photoelectric sensors, proximity sensors, or
limit switches with LEDs, are connected to the PC as input devices, the input bit
may be turned ON erroneously by leakage current. In order to prevent this, con-
nect 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 value and rating for the
bleeder resistor using the following formulas.
If there is a possibility of leakage current causing a transistor or triac to malfunc-
tion, connect a bleeder resistor across the output as shown below.
PC
Determine the value and rating for the bleeder resistor using the following for-
mula.
OFF
DC Input Unit
R R
IN
: Sensor output residual voltage
R
: Sensor control output (load current)
OUT
: Sensor leakage current
leak
Bleeder resistance
Input
power
supply
Bleeder
resistor
I = leakage current in mA
7.2
kW max.
R =
––––––
2.4 x I – 3
2.3
W = W min.
–––
R
OUT
L
R
Bleeder resistor
COM
E
on
R
–––
I
Section 4-4
is always 1.8 mA.
PC
R
Load power supply
49