M-Bus (Meter-Bus) library and examples

[Zen]

Hi everyone, 
i'm trying to following this guide and the one on the main site https://openrb.com/m-bus-integration-in-lm/ to measure water consumption.
We have bought Tecbase Mbus 10 RS232-MBus gateway and we have connected it on our LM5 Lite (i.MX6) SW: 20210521. We are not using the external RS-232 USB converter but the internal RS-232 port of LM5 near the second RS-485 port. We have connected LM5-Tx to MbusGW-Rx and viceversa and both the GND wires.
Following the guide, i can't even scan the bus or getting communicating with it. 
So i've tryied some logging with a scheduled script, changing baudrate from 300 to 9600 but nothing happens:

Code:

if not port then
  require('serial')
  port = serial.open('/dev/RS232', { baudrate = 2400 })
  port:flush()
  line = ''
end

char, err = port:read(1, 60)
log(char, err)

But the request always goes in timeout, getting a response like this:

Code:

* arg: 1
  * nil
* arg: 2
  * string: timeout

I have tryed enabling both RTU 2 and 3 as '/dev/RS232' setting the connection as 'Full-Duplex', but nothing changed.

Can anyone further help or have some ideas on how debug this?