detector

local stair = 0
local masterd = 1

rednet.open("back")

while true do
  event, id, message = os.pullEvent("rednet_message")
  if id == masterd then
     if redstone.getInput("front") == true then
         rednet.send(masterd, "true")
             print(stair.." : oui")
     else
         rednet.send(masterd, "false")
             print(stair.." : non")
     end
  end
end