23
E2E
Connection to a PLC
Required Conditions
Connection to a PLC is possible if the specifications of the PLC and
the Proximity Sensor satisfy the following conditions. (The meanings
of the symbols are given below.)
1.
The ON voltage of the PLC and the residual voltage of the Prox-
imity Sensor must satisfy the following.
V
ON
≤
V
CC
– V
R
2.
The OFF current of the PLC and the leakage current of the Prox-
imity Sensor must satisfy the following.
I
OFF
≥
I
leak
(If the OFF current is not listed in the specifications, take it to be
1.3 mA.)
3.
The ON current of the PLC and the control output (I
OUT
) of the
Proximity Sensor must satisfy the following.
I
OUT(min)
≤
I
ON
≤
I
OUT(max)
The ON current of the PLC will vary, however, with the power sup-
ply voltage and the input impedance used as shown in the follow-
ing equation.
I
ON
= (V
CC
– V
R
–
)/R
IN
Example
In this example, the above conditions are checked for when the PLC
model is the C200H-ID212, the Proximity Sensor model is the E2E-
X7D1-N, and the power supply voltage is 24 V.
1.
V
ON
(14.4 V)
≤
V
CC
(20.4 V) – V
R
(3 V) = 17.4 V: OK
2.
I
OFF
(1.3 mA)
≥
I
leak
(0.8 mA): OK
3.
I
ON
= [V
CC
(20.4 V) – V
R
(3 V) –
≈
4.5 mA
Therefore,
I
OUT(min)
(3 mA)
≤
I
ON
(4.5 mA): OK
V
ON
: ON voltage of PLC (14.4 V)
I
ON
: ON current of PLC (typ. 7 mA)
I
OFF
: OFF current of PLC (1.3 mA)
R
IN
: Input impedance of PLC (3 k
Ω
)
V
R
: Output residual voltage of Proximity Sensor (3 V)
I
leak
: Leakage current of Proximity Sensor (0.8 mA)
I
OUT
: Control output of Proximity Sensor (3 to 100 mA)
V
CC
: Power supply voltage (PLC: 20.4 to 26.4 V)
Values in parentheses are for the following PLC model and Proximity
Sensor model.
PLC: C200H-ID212
Proximity Sensor: E2E-X7D1-N
Precautions for AC/DC 2-wire Proximity Sensors in Operation
Connection
V
PC
V
PC
(4 V)]/R
IN
(3 k
Ω
)
V
PC
: Internal residual voltage of PLC (4 V)
Model
Connection type
Method
Description
DC 2-wire
AND (serial connection)
The Sensors connected together must satisfy the fol-
lowing conditions.
V
S
– N x V
R
≥
Load operating voltage
N: No. of Sensors
V
R
: Residual voltage of each Sensor
V
S
: Supply voltage
If each Proximity Sensor is not supplied with the rat-
ed voltage and current, the indicator will not be lit
properly or unnecessary pulses may be output for
approximately 1 ms.
OR
(parallel connection)
The Sensors connected together must satisfy the fol-
lowing conditions.
N x i
≤
Load reset current
N: No. of Sensors
i: Leakage current of each Sensor
If the MY Relay, which operates at 24 VDC, is used
as a load for example, a maximum of four Proximity
Sensors can be connected to the load.
AC 2-wire
AND (serial connection)
If 100 or 200 VAC is imposed on the Proximity Sen-
sors, V
L
(i.e., the voltage imposed on the load) will be
obtained from the following.
V
L
= V
S
– (residual voltage x No. of Proximity Sen-
sors) (V)
Therefore, if V
L
is lower than the load operating volt-
age, the load will not operate.
A maximum of three Proximity Sensors can be con-
nected in series provided that the supply voltage is
100 V minimum.
Load
Correct
Load
Correct
Load
Load
Load
Vs
×
100 V
Incorrect
Correct