This is a second, independent output that works in parallel to the detector trigger output. Under EN81-20 standards, a 50mm object must be detected within the detection zone at all times – any breach of this must result in the doors going into a low energy mode if the lift is to remain in use. A blocked or damaged diode may create a gap within which a 50mm object will not be detected. If a diode is broken, this could result in non-compliance.
Rather than allowing a single diode blockage to cause a permanent trigger, the diagnostic output can trigger the door’s low energy mode and put the blocked diode in timeout mode. The remaining diodes can operate as normal, the lift can continue to be used, and the detection remains EN81-20 compliant.