startup.lua

localdetector = peripheral.find("environmentDetector")
entities = localdetector.scanEntities(2.5)
while true do
--term.clear()
--term.setCursorPos(1,1)
entities = localdetector.scanEntities(2.5)
if entities ~= nil
then print(#entities)
    if #entities >= 1 then
    redstone.setOutput("back",true)
    else
    rs.setOutput("back",false)
end
end
sleep(0.5)

end