Asyncio serial client not passing in all serial parameters, may help with sync issues

[gbrucepayne]

Versions

• Python: 3.6.9
• OS: Linux Mint 19.3
• Pymodbus: 2.3.0
• Modbus Hardware (if used): SCADAPack 100 (Schneider Electric)

Pymodbus Specific

• Client: rtu - async - asyncio

Description

I see frequent framing errors where the client is not waiting for the response to complete, dropping bytes that cause the CRC to fail. I tried to add 'timeout' parameter but it threw an unexpected keyword error. Digging through the source I see that AsyncioModbusSerialClient init does not include several of the serial parameters including timeout, write_timeout, inter_byte_timeout and flow control options. Those could all be passed through which may help with sync issues.
May overlap other sync related issues.

Code and Logs

Function missing **kwargs for additional serial configuration

 class AsyncioModbusSerialClient(object):
    """
    Client to connect to modbus device over serial.
    """
    transport = None
    framer = None

    def __init__(self, port, protocol_class=None, framer=None,  loop=None,
                 baudrate=9600, bytesize=8, parity='N', stopbits=1):
        """
        Initializes Asyncio Modbus Serial Client
        :param port: Port to connect
        :param protocol_class: Protocol used to talk to modbus device.
        :param framer: Framer to use
        :param loop: Asyncio Event loop
        """
        #: Protocol used to talk to modbus device.
        self.protocol_class = protocol_class or ModbusClientProtocol
        #: Current protocol instance.
        self.protocol = None
        #: Event loop to use.
        self.loop = loop or asyncio.get_event_loop()
        self.port = port
        self.baudrate = baudrate
        self.bytesize = bytesize
        self.parity = parity
        self.stopbits = stopbits
        self.framer = framer
        self._connected_event = asyncio.Event()

Success example followed by Failed example (happens intermittent)

2020-01-05T22:46:41.332Z,[DEBUG],(MainThread),selector_events.__init__:54,Using selector: EpollSelector
2020-01-05T22:46:41.348Z,[DEBUG],(MainThread),__init__.connect:716,Connecting.
2020-01-05T22:46:41.353Z,[DEBUG],(MainThread),__init__._connectionMade:94,Client connected to modbus server
2020-01-05T22:46:41.354Z,[INFO],(MainThread),__init__.protocol_made_connection:733,Protocol made connection.
2020-01-05T22:46:41.356Z,[INFO],(MainThread),__init__.connect:725,Connected to /dev/ttyUSB0
2020-01-05T22:46:41.358Z,[DEBUG],(MainThread),modbusproxy.start_async_test:253,Write to a Coil and read back
2020-01-05T22:46:41.360Z,[DEBUG],(MainThread),__init__.execute:128,send: 0x1 0x5 0x0 0x0 0xff 0x0 0x8c 0x3a
2020-01-05T22:46:41.362Z,[DEBUG],(MainThread),transaction.addTransaction:383,Adding transaction 1
2020-01-05T22:46:41.399Z,[DEBUG],(MainThread),__init__._dataReceived:137,recv: 0x1 0x5 0x0 0x0 0xff 0x0 0x8c 0x3a
2020-01-05T22:46:41.402Z,[DEBUG],(MainThread),rtu_framer.getFrame:180,Getting Frame - 0x5 0x0 0x0 0xff 0x0
2020-01-05T22:46:41.403Z,[DEBUG],(MainThread),factory._helper:266,Factory Response[WriteSingleCoilResponse: 5]
2020-01-05T22:46:41.405Z,[DEBUG],(MainThread),rtu_framer.advanceFrame:115,Frame advanced, resetting header!!
2020-01-05T22:46:41.406Z,[DEBUG],(MainThread),transaction.getTransaction:394,Getting transaction 1
2020-01-05T22:46:41.408Z,[DEBUG],(MainThread),__init__.execute:128,send: 0x1 0x1 0x0 0x0 0x0 0xa 0xbc 0xd
2020-01-05T22:46:41.410Z,[DEBUG],(MainThread),transaction.addTransaction:383,Adding transaction 1
2020-01-05T22:46:41.446Z,[DEBUG],(MainThread),__init__._dataReceived:137,recv: 0x1 0x1 0x2 0xa7 0x1 0x2 0xc
2020-01-05T22:46:41.448Z,[DEBUG],(MainThread),rtu_framer.getFrame:180,Getting Frame - 0x1 0x2 0xa7 0x1
2020-01-05T22:46:41.449Z,[DEBUG],(MainThread),factory._helper:266,Factory Response[ReadCoilsResponse: 1]
2020-01-05T22:46:41.450Z,[DEBUG],(MainThread),rtu_framer.advanceFrame:115,Frame advanced, resetting header!!
2020-01-05T22:46:41.451Z,[DEBUG],(MainThread),transaction.getTransaction:394,Getting transaction 1
2020-01-05T22:46:41.452Z,[INFO],(MainThread),modbusproxy.start_async_test:258,read bits ReadBitResponse(16)

*** FAILURE LOG ***

2020-01-05T22:46:59.222Z,[DEBUG],(MainThread),selector_events.__init__:54,Using selector: EpollSelector
2020-01-05T22:46:59.234Z,[DEBUG],(MainThread),__init__.connect:716,Connecting.
2020-01-05T22:46:59.240Z,[DEBUG],(MainThread),__init__._connectionMade:94,Client connected to modbus server
2020-01-05T22:46:59.242Z,[INFO],(MainThread),__init__.protocol_made_connection:733,Protocol made connection.
2020-01-05T22:46:59.245Z,[INFO],(MainThread),__init__.connect:725,Connected to /dev/ttyUSB0
2020-01-05T22:46:59.247Z,[DEBUG],(MainThread),modbusproxy.start_async_test:253,Write to a Coil and read back
2020-01-05T22:46:59.249Z,[DEBUG],(MainThread),__init__.execute:128,send: 0x1 0x5 0x0 0x0 0xff 0x0 0x8c 0x3a
2020-01-05T22:46:59.251Z,[DEBUG],(MainThread),transaction.addTransaction:383,Adding transaction 1
2020-01-05T22:46:59.285Z,[DEBUG],(MainThread),__init__._dataReceived:137,recv: 0x1 0x5 0x0 0x0 0xff 0x0 0x8c 0x3a
2020-01-05T22:46:59.287Z,[DEBUG],(MainThread),rtu_framer.getFrame:180,Getting Frame - 0x5 0x0 0x0 0xff 0x0
2020-01-05T22:46:59.288Z,[DEBUG],(MainThread),factory._helper:266,Factory Response[WriteSingleCoilResponse: 5]
2020-01-05T22:46:59.290Z,[DEBUG],(MainThread),rtu_framer.advanceFrame:115,Frame advanced, resetting header!!
2020-01-05T22:46:59.291Z,[DEBUG],(MainThread),transaction.getTransaction:394,Getting transaction 1
2020-01-05T22:46:59.292Z,[DEBUG],(MainThread),__init__.execute:128,send: 0x1 0x1 0x0 0x0 0x0 0xa 0xbc 0xd
2020-01-05T22:46:59.294Z,[DEBUG],(MainThread),transaction.addTransaction:383,Adding transaction 1
2020-01-05T22:46:59.317Z,[DEBUG],(MainThread),__init__._dataReceived:137,recv: 0x1 0x1 0x2 0xa7
2020-01-05T22:46:59.318Z,[DEBUG],(MainThread),rtu_framer.processIncomingPacket:232,Frame check failed, ignoring!!
2020-01-05T22:46:59.319Z,[DEBUG],(MainThread),rtu_framer.resetFrame:128,Resetting frame - Current Frame in buffer - 0x1 0x1 0x2 0xa7
2020-01-05T22:46:59.333Z,[DEBUG],(MainThread),__init__._dataReceived:137,recv: 0x1 0x2 0xc
2020-01-05T22:46:59.335Z,[DEBUG],(MainThread),rtu_framer.processIncomingPacket:232,Frame check failed, ignoring!!
2020-01-05T22:46:59.336Z,[DEBUG],(MainThread),rtu_framer.resetFrame:128,Resetting frame - Current Frame in buffer - 0x1 0x2 0xc

[dhoomakethu]

This is fixed with. https://github.com/riptideio/pymodbus/tree/asyncio-bug-fixes Refer e402d9f#diff-90d825c299aa37cc31eb357be29777fbR731.

Please check and confirm.