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  1. Qt
  2. QTBUG-89995

Bad value calculated&used for InterFrameDelay in QModbusRtuSerialSlavePrivate

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: P2: Important
    • Resolution: Done
    • Affects Version/s: 5.15.2
    • Fix Version/s: 5.15, 6.2.0 Alpha
    • Component/s: SerialBus: MOD Bus
    • Labels:
      None
    • Platform/s:
      Linux/X11, Windows
    • Commits:
      c990bdbf8ec922dd7702a2a0e33b9b70db3ac6ee (qt/qtserialbus/dev)

      Description

      I'm running MODBUS server on the desktop PC via USB-RS485 adapter (baudrate = 115200) and I have request timeouts and stalls. I have activated low level QtSerialBus logs and saw this:

      Dropping older ADU fragments due to larger than 3.5 char delay (expected: 2 , max: 15 )

      Apparently, m_interFrameDelayMilliseconds is too low for my setup, however there is no direct way to fix it (like QtModbusRtuSerial*Master*::setInterFrameDelay).

      Dirty workaround is to open serial port at lowest baudrate (i.e. 1200) and change it via direct call to the QSerialPort::setBaudRate.

      So, there are either a bug in m_interFrameDelayMilliseconds or there should be QtModbusRtuSerial*Slave*::setInterFrameDelay call, or both.

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            Assignee:
            heimrich Karsten Heimrich
            Reporter:
            hate-engine Andrey Batyiev
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              Dates

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              Updated:
              Resolved:

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