Datasheet
A-242 Standard Photoelectric Sensors
The sensor is normal if the control output var-
ies when the self-diagnostic external input is 
ON and OFF. The sensor is abnormal if the 
control output does not vary when the self-di-
agnostic external input is turned ON or OFF.
Note:Before using the self-diagnostic external input func-
tion, the incident light beam to the sensor must not be 
blocked by an object.
Timer and Turbo Switch (Sensors with Self-diagnostic Output Function)
The E3S-A Sensor equipped with the self-diagnostic feature 
incorporates an OFF-delay timer that can be adjusted within a 
range of 0 to 100 ms.
The emitter of the through-beam sensor with the self-diagnos-
tic feature incorporates a turbo switch. When this switch is on, 
the intensity of the red LED light source can be increased to 
make a brighter spot. The OFF-delay time adjustor of the ret-
roreflective and the 20-cm diffuse reflective sensor is used as 
a turbo switch. When the adjustor is pressed, it functions as a 
turbo switch to automatically increase the power of the light 
source to create a brighter light spot. Do not press the adjustor 
when turning it
Sensitivity Adjustment (Reflective Sensors)
Unlike conventional photoelectric sensors, the variation in the 
sensitivity of E3S photoelectric sensors is minimal. This 
means the sensitivity can be adjusted on only a single photo-
electric sensor, and then the adjustors on the other photoelec-
tric sensors can be set to the same scale position. There is no 
need to adjust the sensitivity of each photoelectric sensor in-
dividually.
Indicator
ON
OFF
External
diagnostic input
ON
OFF
LED for emitter
ON
OFF
E3S-AT@/E3S-AR@ Emitter
Indicator
Main 
circuit
Brown
Blue
Pink
10 to 30 
VDC
(with PNP output)
(with NPN output)
External-diagnostic 
input
0 V
Item Position A Position B Setting
Sensing 
condition
---
Sensivity 
adjustor
Indicators
Procedure Locate a sensing object at the sensing 
distance, set the sensitivity adjustor to 
the minimum scale position, and grad-
ually increase sensitivity by turning the 
sensitivity adjustor clockwise until the 
incident light indicator (red LED) is ON. 
Position A is where the indicator has 
turned ON. Regard the maximum scale 
position as Position A if the indicator 
does not turned ON at full sensitivity.
Remove the sensing object and gradu-
ally decrease sensitivity by turning the 
sensitivity adjustor counterclockwise 
from the maximum scale position until 
the incident light indicator (red LED) is 
OFF. Position B is where the indicator 
has turned off. Regard the minimum 
scale position as Position B if the indi-
cator does not turned ON at minimum 
sensitivity.
Set the sensitivity indicator to the posi-
tion between Positions A and B (in 
some cases, Positions A and B are op-
posite of the above example). The pho-
toelectric sensor will then work 
normally if the stability indicator (green) 
is lit with and without the sensing ob-
ject. If it is not lit, stable operation can-
not be expected, in which case a 
different detection method must be ap-
plied.
Photoelectric sensor
Sensing object
Sensing object
Photoelectric sensor
A
Min Max
Min Max
B
B
Min Max
A
OFF ON
STABILITY
(green)
LIGHT
(red)
OFF OFF
STABILITY
(green)
LIGHT
(red)
OFF ON
STABILITY
(green)
LIGHT
(red)










