Lm2 and Lm3 ! port USB ?

[phongvucba]

Hi everybody !
I have trouble following:
Write a script to check the data via USB to the LM.
-----------
require ('serial')

if not ready then
   Ready = true
   port, err = serial.open ('/ dev / ttyUSB2')
   log (port, err)
end
-----------
On Lm2 will be announced:
Lua serials @ / dev / ttyUSB2; baud: 115200; parity: none, data bits: 8, stop bits: 1, duplex: full, flow: none
Such is the success!
-----------
On LM3 will be announced:
* Arg: 1
   * luaserial
* Arg: 2
   * nil
Such is successful or unsuccessful?
Plug the device was still on the LM2 and LM3 is the same USB device

[admin]

Your LM2 has older serial library, that's why the output is different. Anyway, if port cannot be open your port variable will be nil and err will be a string cannot open port

[phongvucba]

Can you give me one script writes on the latest LM3?
Script to check if USB ports are open yet?

[admin]

Do you need to check if port is present in the system?

Code:

if io.exists('/dev/ttyUSB0') then
  alert('Port OK')
else
  alert('Port not found')
end

[phongvucba]

good. Thank so much admin!