Datasheet

221
EX-20
PRECAUTIONS FOR PROPER USE
Mounting
• Mount using M3 screws. The tightening torque should be
0.5 N m or less.
Stability indicator
• The stability indicator (green) lights up when the incident
light intensity has sufficient margin with respect to the
operation level.
If the incident light intensity level is such that the stability
indicator lights up, stable sensing can be done without the
light received operation and the light interrupted operation
being affected by a change in ambient temperature or sup-
ply voltage.
Others
• Do not use during the initial transient time (50 ms) after
the power supply is switched on.
• If sensors are mounted close together and the ambient
temperature is near the maximum rated value, provide for
enough heat radiation / ventilation.
• If a reflective object is present in the background, the
sensing of EX-28A(-PN) and EX-28B(-PN) may be
affected. When setting the sensor, make sure to confirm
that the reflective object has no effect. In case the
reflective object affects the sensing, take measures such
as removing the reflective object or coloring it in black, etc.
Operation of stability indicator
Output operation
Incident
light
margin
Light
interruption
margin
Output
operation
level
0
100
0
Incident light intensity (%)
Setting distance
15 % approx.
25 % approx.
Lights up
Light received operation
Light interrupted operation
Lights up
Lights off
Note: Operation mode switch should be turned fully till it stops.
Light-ON mode is obtained when the operation
mode switch (located on the receiver) is turned fully
clockwise (L side).
Dark-ON mode is obtained when the operation
mode switch (located on the receiver) is turned fully
counterclockwise (D side).
Switch position
Description
L
D
D
L
Operation mode switch (EX-23 only)
1
2
3
4
Turn the sensitivity adjuster fully counterclockwise
to the minimum sensitivity position (• mark).
In the light received condition, turn the sensitivity
adjuster slowly clockwise and confirm the pointoint
where the sensor enters the ‘Light’ state operation.
In the dark condition, turn the sensitivity adjuster
further clockwise until the sensor enters the ‘Light’
state operation and then bring it back to confirm
point where the sensor just returns to the ‘Dark’
state operation.
If the sensor does not enter the ‘Light’ state operation
even when the sensitivity adjuster is turned fully
clockwise, this extreme position is point .
The position at the middle of points andand
is the optimum sensing position.
Step Description
Notes: 1) Use the attached adjusting screwdriver to turn the adjuster slowly. Turning
with excessive strength will damage the adjuster.
Notes: 2) In case of using EX-22 at a sensing distance of 50 mm 1.969 in or less,
take care that the sensitivity adjustment range becomes extremely narrow.
()
Front sensing Side sensing
Note: When mounting the front sensing type sensor, use M3 pan head
screws without washers, etc.
• When mounting the front sensing type from the backside, fit
the mounting spacer (MS-EX20-FS) and fix with screws.
M3 pan head screws
(Note)
M3 screws
1
Fit the mounting spacer
on the sensor.
2
Align the mounting holes of
the mounting spacer and the
sensor and mount with M3
screws. The tightening torque
should be 0.5 Nm or less.
Mounting method
Mounting
spacer (Optional)
M3 screws
MAX
A
MAX
A
B
MAX
A
B
Optimum position
Sensitivity adjustment (side sensing type only)
Sensitivity adjuster
This product is not a safety sensor. Its use is not
intended or designed to protect life and prevent body
injury or property damage from dangerous parts of
machinery. It is a normal object detection sensor.
Glossy object sensing [EX-29(-PN)]
• Please take care of the following points when detecting
materials having a gloss.
1
Make L, shown in the diagram, sufficiently long.
2
Install at an angle of 10 to 30 degrees to the sensing
object.
L
10 to 30 
Make L sufficiently long
Reflector
Sensing object
Glossy surface
Sensor
Wiring
• Make sure that the power supply is off while wiring.
• Verify that the supply voltage variation is within the rating.
• If power is supplied from a commercial switching regulator,
ensure that the frame ground (F.G.) terminal of the power
supply is connected to an actual ground.
• In case noise generating equipment (switching regulator,
inverter motor, etc.) is used in the vicinity of this product,
connect the frame ground (F.G.) terminal of the equipment
to an actual ground.
• Do not run the wires together with high-voltage lines or
power lines or put them in the same raceway.
• This can cause malfunction due to induction.
MAX
A
A
B
B
B
08/2005