Datasheet

9
B5W-LB series Light Convergent Reflective Sensor
B
5
W
-
L
B
● Handling during Wiring
(1) If a force is applied to the connection area between the ter-
minal and connector by bending or pulling the cable after the
wiring is completed, the connector contact part or connec-
tion area with the cable may be damaged, resulting in con-
tact failure. Make sure that a stress (external force) as
shown in the figure below is not applied to the connection
area between the terminal and connector when routing and
connecting cables or harnesses.
(2) Do not perform cord wiring when power supply voltage is
applied. Doing so may result in breakage.
● Design
Light Convergent Reflective Sensor
A modulated-light type of light convergent reflective sensor is
used. When designing, give proper consideration to the power
supply and cable lengths used.
Light convergent reflective sensors are more easily affected than
the sensors with Nonmodulated Light.
Reasons for Interference from Power and Cable Length
on the sensors with Modulated Light
An LED emitter is pulse-lighted to produce modulated light. A
large current momentarily flows to the sensors in sync with this
pulse timing. This causes a pulsating consumption current. A
photoelectric sensor incorporates a capacitor with sufficient
capacity, and is virtually unaffected by the pulse of the consump-
tion current. With a small sensor, however, it is difficult to have a
capacitor with a sufficient capacity. Accordingly, when the cable
length is long or depending on the type of power source, it may
become impossible to keep up with the pulse of the consumption
current and operation may become unstable.
Countermeasures
Adding a Capacitor
• Attach a capacitor of 10 μF min. to the wires as close as possi-
ble to the Sensor. (Use a capacitor with a dielectric strength
that is at least twice the Sensor's power supply voltage. Do not
use tantalum capacitors. A short-circuit may cause the capaci-
tor to ignite due to the large current flow.)
<Cable Length>
• Design the configuration so that the maximum total cable
length for the Photomicrosensor with Modulated Light is 2 m.
• When using a cable longer than 2 m, attach a capacitor (e.g.,
an aluminum electrolytic capacitor) with a capacity of 10 μF
min. to the wires. The distance between the terminal and the
capacitor must be within 2 m.
Make sure that the total cable length is no longer than 5 m. To
use a cable length longer than 5 m, use a PLC or other means
to read the sensor output and then transmit the signals using a
PLC's communications.
• Although cables are capable of being extended longer than 5
m, performance is likely to be affected by noise interference
from adjacent cables and other devices.
Voltage drops due to the resistance of the cable material itself
will also influence performance. Therefore, factors, such as
the difference in voltage between the end of the cable and the
sensor and noise levels, must be given full consideration.
Countermeasures for Switching Power Supplies
• Take either of the following countermeasures as required if
connecting a sensor to a switching power supply.
1. Attach a capacitor of 10 μF min. to the wires as close as
possible to the sensor. (Use a capacitor with a dielectric
strength that is at least twice the sensor's power supply
voltage. Do not use tantalum capacitors. A short-circuit may
cause the capacitor to ignite due to the large current flow.
Do not use tantalum capacitors. A short-circuit may cause
the capacitor to ignite due to the large current flow.)
2. Connect to the 0-V line of the power source or connect to
the power source via a capacitor of approximately 0.47 μF
to reduce the impedance of the mounting base to prevent
inductive noise from entering the mounting base. Or, con-
nect by way of a capacitor (approx. 0.47 μF).
3. Connect the noise filter terminal (neutral terminal to ACG)
of the switching power supply to the case (FG) and 0-V ter-
minal of the power supply.
The line connected as mentioned above should be
grounded or connected to the mounting base to ensure sta-
ble operation.
(Recommended by power supply manufacturers.)
External force
External force
External force
Emitter
(LB)
Main
circuit
24
VDC
10 µF
min.
Vcc
OUT
GND
Current
2 m max.
24 V
0 V
Capasitance of
10 µF min.
Extension cable
Sensor
2 m max.
24 V
0 V
Capasitance of
10 µF min.
Extension cable
Sensor
0V
G
C
(0.47 µF)
Switching
Power Supplies
Mounting
base
+V
Sensor