Datasheet

 PRECAUTIONS FOR AC OR DC 2-WIRE PROXIMITY SENSORS IN OPERATION, CONTINUED
Model Connection Type Method Description
AC
2-wire
OR
(parallel connection)
Load
Load
VAC power
supply V
S
A
B
A
B
Incorrect
Correct
In principle, more than two Proximity Sensors
cannot be connected in parallel.
Provided that Proximity Sensor A does not
operate with Proximity Sensor B simultaneously
and there is no need to keep the load operating
continuously, the Proximity Sensors can be
connected in parallel. In this case, however, due
to the total leakage current of the Proximity
Sensors, the load may not reset properly.
It is not possible to keep the load operating
continuously with Proximity Sensors A and B in
simultaneous operation to sense sensing objects
due to the following reason.
When Proximity Sensor A is ON, the voltage
imposed on Proximity Sensor A will drop to
approximately 10 V and the load current flows
into Proximity Sensor A, and when one of the
sensing objects is close to Proximity Sensor B,
Proximity Sensor B will not operate because the
voltage imposed on Proximity Sensor B is 10 V,
which is too low. When Proximity Sensor A is
OFF, the voltage imposed on Proximity Sensor B
will reach the supply voltage and Proximity
Sensor B will be ON. Then, Proximity Sensor A
as well as Proximity Sensor B will be OFF for
approximately 10 ms, which resets the load for
an instant. To prevent the instantaneous
resetting of the load, use a relay as shown on the
left.
DC
3-wire
AND
(serial connection)
Load
Correct
The Sensors connected together must satisfy the
following conditions.
i
L
+(N--1)xi  Upper-limit of control output of
each Sensor
V
S
-- N x V
R
 Load operating voltage
N: No. of Sensors
V
R
: Residual voltage of each Sensor
V
S
: Supply voltage
i: Current consumption of the Sensor
i
L
: Load current
If the MY Relay, which operates at 24 VDC, is
used as a load for example, a maximum of two
Proximity Sensors can be connected to the load.
OR
(parallel connection)
Load
Correct
A minimum of three Sensors with current outputs
can be connected in parallel. The number of
Sensors connected in parallel varies with the
Proximity Sensor model.
E2E2 E2E2