Omron CP1E-E10DT-A, User Manual

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5-19
5 Installation and Wiring
CP1E CPU Unit Hardware User’s Manual(W479)
5-3 W
iri
n
g
5
5-3-3
I/O
W
ir
in
g
When using a two-wire sensor with a 24-VDC input device, check that the following conditions have
been met. Failure to meet these conditions may result in operating errors.
(1) Relation between voltage when the PLC is ON and the sensor residual voltage:
V
ON
≤
V
CC
−
V
R
(2) Relation between current when the PLC is ON and sensor control output (load cur-
rent):
I
OUT
(min)
≤
I
ON
≤
I
OUT
(max)
I
ON
=(V
CC
−
V
R
−
1.5[PLC internal residual voltage]*)/R
IN
When I
ON
is smaller than I
OUT
(min), connect a bleeder resistor R.
The bleeder resistor constant can be calculated as follows:
R
≤
(V
CC
−
V
R
)/(I
OUT
(min)
−
I
ON
)
Power W
≥
(V
CC
−
V
R
)
2
/R
×
4(allowable margin)
(3) Relation between current when the PLC is OFF and sensor leakage current:
I
OFF
≥
I
leak
Connect a bleeder resistor if I
leak
is greater than I
OFF
.
Use the following equation to calculate the bleeder resistance constant.
R
≤
R
IN
×
V
OFF
/(I
leak
×
R
IN
−
V
OFF
)
Power W
≥(
V
CC
−
V
R
)
2
/R
×
4(allowable margin)
(4) Precautions on Sensor Inrush Current
An incorrect input may occur due to sensor inrush current if a sensor is turned ON after the
PLC has started up to the point where inputs are possible.
Determine the time required for sensor operation to stabilize after the sensor is turned ON
and take appropriate measures, such as inserting into the program a timer delay after turn-
ing ON the sensor.
Precautions When Connecting a Two-wire DC Sensor
Vcc: Power voltage
Vr: Sensor output residual voltage
Von: PLC ON voltage
Iout: Sensor control current (load current)
Voff: PLC OFF voltage
Ion: PLC ON current
Ileak: Sensor leakage current
Ioff: PLC OFF current
R: Bleeder resistance
Rin: PLC input impedance
DC Input Unit
R V
R
V
CC
Two-wire sensor
R
IN