SICK WLG4S - Additional Functions; Troubleshooting

6.6 Additional functions
Alarm: Operation with borderline light reception
Alarm output: The sensor (WLG4S) features a pre-failure notification output that issues
a notification if the sensor is only ready for operation to a limited extent. The yellow LED
flashes in this case. This may be the result of incorrect alignment, contaminated optics
surfaces, and/or insufficient remission of light by the reflector. The sensor features an
alarm output that outputs a discrete signal if the sensor is operated below this limit
condition.
The alarm output can be parameterized via IO Link. You can find details in the follow‐
ing document: Technical Information: Photoelectric sensors, SICK Smart Sensors /
IO-Link.
7 Troubleshooting
The Troubleshooting table indicates measures to be taken if the sensor stops working.
Table 11: Troubleshooting
LED/fault pattern Cause Measures
Yellow LED does not light up
even though the light beam
is aligned to the reflector and
there is no object in the path of
the beam
No voltage or voltage below
the limit values
Check the power supply,
check all electrical connec‐
tions (cables and plug connec‐
tions)
Voltage interruptions Ensure there is a stable power
supply without interruptions
Sensor is faulty If the power supply is OK,
replace the sensor
Green LED flashes IO-Link communication -
Digital outputs not according to
graphic
IO-Link communication -
Digital outputs not according to
graphic
Parameter settings made
manually, which deviate from
the standard
Initiate a factory reset. The
digital outputs are reset to
factory settings.
Yellow LED flashes; if Alarm is
present then take note of the
corresponding output signal
Sensor is still ready for oper‐
ation, but the operating condi‐
tions are not ideal
Check the operating condi‐
tions: Fully align the beam
of light (light spot) with the
reflector. / Clean the optical
surfaces (sensor and reflec‐
tor). / Reflector is not suitable
for the application in question
(we recommend only using
SICK reflectors) / Check sens‐
ing range and adjust if neces‐
sary. / Distance between the
sensor and the reflector is too
long
Yellow LED flashes (only briefly) Teach-in mode Check the teach-in mode
Signal interruptions when
object is detected
Depolarizing property of the
object surface (e.g., tape),
reflection
Reduce sensitivity or change
the position of the sensor
OPERATING INSTRUCTIONS
80282151N09/2024-03-12 | SICK O P E R A T I N G I N S T R U C T I O N S | WLG4S
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Subject to change without notice
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