writer doesn't write anything

[anormalrobot]

Hello,

When i was trying to send a data with following code nothing happens:

from asyncio import get_event_loop
from serial_asyncio import open_serial_connection

async def run():
reader, writer = await open_serial_connection(url='/dev/ttyUSB1', baudrate=115200)
writer.write(b'Hello World')

loop = get_event_loop()
loop.run_until_complete(run())

But when i want to read and write everything works perfectly. Is there any way to write only async serial.

Have a great day :)

[nlhnt]

How do you now that nothing happens?
The message is send to /dev/ttyUSB1 and should the device do something when it receives b'Hello World'?
Is there some physical response or lack of that?

[anormalrobot]

I had an arduino connected on /dev/ttyUSB1 and if it receives any data (if(Serial.available()>0)) it has to blink. So nothing blinks.
I solved problem with write than read structure. But still nothing works with only write structure.

[katomaso]

Your data are most likely stuck in the write buffer. What you did was to append your data to a write buffer and then immediately ended the loop. This would call _connection_lost and clear the write buffer. The solution should be

async def run():
    reader, writer = await open_serial_connection(url='/dev/ttyUSB1', baudrate=115200)
    writer.write(b'Hello World')
    writer.close()

loop = get_event_loop()
loop.run_until_complete(run())