4-41
4 Installation and Wiring
NJ-series CPU Unit Hardware User’s Manual (W500)
4-4 Wiring
4
4-4-6 Connecting I/O Devices
(3) Relation between current when the Controller is OFF and sensor leakage current:
I
OFF
Ileak
Connect a bleeder resistor if I
leak
is greater than IOFF. Use the following equation to calcu-
late the bleeder resistance constant.
R (R
IN VOFF)/(Ileak RIN VOFF
)
Power W (VCC VR)
2
/R 4 [allowable margin]
(4) Precautions on Sensor Surge Current
An incorrect input may occur if a sensor is turned ON after the Controller has started up to
the point where inputs are possible. Determine the time required for sensor operation to sta-
bilize after the sensor is turned ON and take appropriate measures, such as inserting a
timer delay into the user program after turning ON the sensor.
Programming Example
In this example, the sensor's power supply voltage is used as the input to SensorVcc. A timer delay
(100 ms for an OMRON Proximity Sensor) is added to the user program to wait for sensor operation
to stabilize. After the timer times out and then the SensorOK input changes to TRUE, a sensor input
to the Sensorln input causes InData to change to TRUE.
Variable Data type Initial value Address Comment
SensorVcc BOOL FALSE IOBus://rack#0/slot#0/Ch1_In/Ch1_In00 Sensor power supply volt-
age
SensorIn BOOL FALSE IOBus://rack#0/slot#0/Ch1_In/Ch1_In01 Input from sensor
SensorOK BOOL FALSE --- Sensor stable operation
flag
InData BOOL FALSE --- Sensor input data valid flag
egPowerDelay TON --- --- Sensor input delay timer
V
R
R
V
CC
R
IN
VCC:
V
ON:
V
OFF:
I
ON:
I
OFF:
R
IN:
V
R:
I
OUT:
I
leak:
R:
Sensor output residual current
Sensor control current (load current)
Sensor leakage current
Bleeder resistance
Power voltage
Controller ON voltage
Controller OFF voltage
Controller ON current
Controller OFF current
Controller input impedance
Two-wire sensor
DC Input Unit
SensorVcc
T#100ms
SensorOK SensorIn
egPowerDelay
TON
In Q
PT ET
SensorOK
InData
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