RS485 signal collision

[Hadeel]

Dear Daniel 

I tried this in a resident script with 0 interval like this but it seems this script does not get executed every second...
When I remove the last line "res, err = port:read(17)" it gets executed every second.
Could you tell me if I am doing anything wrong?

Code:

if not port then
  require('serial')
  port =  serial.open('/dev/RS485-1', {
  baudrate = 19200,
  databits = 8,
  stopbits = 1,
  parity = 'none',
  duplex = 'half'
})
end

log('executed')


if storage.get('coldBathAutoStartCommand') ~= nil  then
port:write(storage.get('coldBathAutoStartCommand'))
os.sleep(1)
port:write(':RR\r\n')
storage.set('coldBathAutoStartCommand', nil)
end


port:flush()
res, err = port:read(17)