Stream sensor (serial) not reliable

[megapearl]

First of all thanks for your time and great code.

• I have read the README.md file and visited the Documentation to see if the information there helps.

Describe the bug
The string that comes from the serial port is sometimes incomplete.

Expected behavior
A complete string

Error messages and traceback

No errors

Config

mqtt:
  host: shed-mqtt.*redacted*.com
  port: 1883
  user: *redacted*
  password: *redacted*
  topic_prefix: home-domotica
  client_id: cupboard-domotica
  status_topic: cupboard_domotica/status
  reconnect_delay: 1

gpio_modules:
  - name: mcp23017_binary_sensor
    module: mcp23017
    chip_addr: 0x20
  - name: mcp23017_switch
    module: mcp23017
    chip_addr: 0x21

digital_inputs:
  - name: hallway_frontdoor
    module: mcp23017_binary_sensor
    pin: 14
    inverted: false
    pullup: true
    retain: true
    ha_discovery:
      component: binary_sensor
      name: Hallway Frontdoor

digital_outputs:
  - name: frontdoor_lock
    module: mcp23017_switch
    pin: 0
    inverted: true
    retain: true
    initial: high
    publish_initial: true
    ha_discovery:
      component: switch
      name: Frontdoor Lock
      device_class: lock

stream_modules:
  - name: cupboard_alarm_stream
    module: serial
    device: /dev/ttyUSB1
    baud: 19200
    bytesize: 8
    parity: none
    stopbits: 1
    cleanup: true
    retain: true
    read: true
    write: false
    read_interval: 0.25

Hardware

• Platform: Raspberry Pi 4
• Connected hardware: mcp23017, usb to serial dongle (startech)

System:

• OS: Linux cupboard-domotica 6.1.21-v8+ #1642 SMP PREEMPT Mon Apr 3 17:24:16 BST 2023 aarch64 GNU/Linux
• Python version: Python 3.9.2
• User you're running as: gpio2mqtt
• Using a virtualenv?: yes

Additional context
I hooked up an old alarm system which has a serial "printer" port, that "prints" strings to the serial port.
When someone uses a badge or opens a door, the alarm system output it to the serial port.

The strings that mqtt-io reads are incomplete, They should be something like:
"4560 21:23:37 10/07/23 Access granted on Door 3 �for user 2 Donald�"

In 5 of 10 cases this is working as expected, but most of the time the string received is a part of it like:
"ess granted on Door 3 �for user 2 Donald�"

I tried different versions of mqtt-io.

cd /home/gpio2mqtt
source bin/activate
#pip install --upgrade mqtt-io
#pip install --upgrade git+https://github.com/flyte/mqtt-io.git@feature/trio
#pip install --upgrade git+https://github.com/flyte/mqtt-io.git@develop
pip install --upgrade git+https://github.com/flyte/[email protected]

I tried using different read_interval for the stream_modules, from 0.1 to 2.0

I read through:
https://mqtt-io.app/2.2.9/#/config/reference/stream_modules/
https://github.com/flyte/mqtt-io/blob/develop/mqtt_io/modules/stream/serial.py
to find other options like buffering but could not find it.

I tried cleanup: false and cleanup: true
It doesn't make any difference, what else can I try?

What could be the problem? it seems like a buffer issue to me, but I don't know for sure.

Best Regards,
Donald.