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FAQ01290 of Displacement Sensors / Measurement Sensors FAQ

FAQ No. FAQ01290

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E4PA Ultra Sonic Displacement/Measuring Sensor A1 (power indicator, green LED) and A2 (error indicator, red LED) indicators flash alternately and the E4PA is not operating properly. What is causing this, and what can we do to resolve the problem?



1.The reflected sound wave is unstable.

2.The surface of the sensing object is not flat or the distance setting is near the maximum rated detection distance.


1.Use the Sensor at a closer distance.

2.If you cannot move the Sensor any closer, use a Sensor that has a longer detection distance. For example, if the Sensor that you are currently using is the E4PA-LS400-M1 with a detection distance of 500 to 4,000 mm, then use a E4PA-LS600-M1 with detection distance of 800 to 6,000 mm instead.