Low signal or maintenance request. Check the fronts of the active and the reflector units are clean. If necessary correct the barrier alignment and check that on covering the reflector, you get the steady yellow LED on.
The on board barrier has clean contacts so can be interfaced with any in / out or central fire detection module. The resistance values are indicated in the particular manual for the central unit or the input module used.
The barrier reset must be done with the power supply to the barrier switched off for about two seconds.