Reference this instruction sheet (page 8) for all details: http://us.allegion.com/content/dam/allegion-us-2/web-documents-2/InstallInstructions/Von_Duprin_Electrical_Options_Booklet_Installation_Instructions_107111.pdf
In summary:
Normal Operation:
LED will flash "ON" briefly when +24V DC is applied.
This is when potted module is operational and power is being applied to the exit device.
LED then goes into a steady "OFF" state and holds there, even with +24V continuing to be applied to the module.
Over voltage Condition
LED will turn on and remain on when over voltage condition detected.
LED will stay in this state until power is removed from the module.
The over voltage condition is defined as 30.0 VDC or greater.
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