shutter timer based on detector

Code:
if not client then
  timers = {
    ['0/0/1'] = {
      output = '0/0/3', -- output value object
      timeout = 300, -- timeout in seconds
      onvalue = nil, -- value to send when timer is turned on (nil to disable)
      offvalue = true, -- value to send when timer is turned off (nil to disable)
    },
  }

  function timerset(timer, value, ticks)
    timer.ticks = ticks
    grp.write(timer.output, value)
  end

  grp.sender = 'tm'

  client = require('localbus').new(0.1)
  client:sethandler('groupwrite', function(event)
    local timer = timers[ event.dst ]
    if timer and event.sender ~= grp.sender then
      local value = tonumber(event.datahex, 16) or 0
      if value == 1 then
        timerset(timer, timer.onvalue, timer.timeout)
      end
    end
  end)
end

client:loop(1)

for _, timer in pairs(timers) do
  if timer.ticks then
    timer.ticks = timer.ticks - 1

    if timer.ticks == 0 then
      timerset(timer, timer.offvalue)
    end
  end
end