Find the LN card, it's either in the hoistway or in the controller. It will have CAT5 in and out. Check pico fuses and look for a slow steady flash rate. If it's flashing fast, there is an SPI loop problem but that should give you a fault. The SPI loop runs from the out jack on that LN card, in then out of every L24 card in every hall fixture (buttons and gongs, not PI) then it comes back to the IN on the LN card. A problem with any of these boards or cables can cause a problem or open the SPI loop. The L24 cards in the fixtures are plug and play, the LN card is not! Do not swap it with another one or install a new one without loading a LON config into it.
