Timeout for ModbusUdpClient

If the slave stops, the UDP client realized with pymodbus hangs (on OS X). There seems to be no way to specify a timeout on the underlying socket as for the ModbusSerialClient. The following would allow to use a timeout argument using the newly passed down kwargs.

class ModbusUdpClient(BaseModbusClient):
    def __init__(self, host='127.0.0.1', port=Defaults.Port,
        framer=ModbusSocketFramer, **kwargs):
        ''' Initialize a client instance

        :param host: The host to connect to (default 127.0.0.1)
        :param port: The modbus port to connect to (default 502)
        :param framer: The modbus framer to use (default ModbusSocketFramer)
        '''
        self.host = host
        self.port = port
        self.socket = None
        self.timeout  = kwargs.get('timeout',  Defaults.Timeout)
        BaseModbusClient.__init__(self, framer(ClientDecoder()),**kwargs)

    def connect(self):
        ''' Connect to the modbus tcp server

        :returns: True if connection succeeded, False otherwise
        '''
        if self.socket: return True
        try:
            family = ModbusUdpClient._get_address_family(self.host)
            self.socket = socket.socket(family, socket.SOCK_DGRAM)
            self.socket.settimeout(self.timeout)
        except socket.error, ex:
            _logger.error('Unable to create udp socket %s' % ex)
            self.close()
        return self.socket != None

An update on the python3 build would be nice too.

Thanks,
Marko

[bashwork]

I am fine adding this, but I will keep the default set to None. As for the python3 branch, I know a few groups who are using it, but I believe only for TCP async clients. Ideally I don't want two branches (just one), but I have been wary to pull the switch quite yet without more people trying it out and reporting their results on both 2.7> and 3.x.

[myTonino]

Thanks for considering this for integration. Default to None is fine. Regarding Python3: the modbus lib is the final lib blocking the move of my open-source roasting app Artisan to move to Python3. I used the minimialmodbus lib up to now exactly for its Python3 compatibility, but then wanted to add TCP/UDP support and moved to pymodbus as I saw and tested successfully the Python3 branch. Then I discovered the timeout issue on UDP and could solve it only nicely by some monkey patching (class overwriting) and parameter passing (only available in the latest version and not the Python3 branch).

So for me the Python3 branch worked as expected (mostly tested the RTU and UDP part) and I would vote for ONE branch that supports both Python version.

[myTonino]

Upps. Note that behind myTonino and MAKOMO is the same person, me. Thanks for giving us pymodbus!

[bashwork]

Fixed with b13c89d

[Eventect]

I believe the modification above has not been committed properly. It should read, as MAKOMO suggested:

self.socket.settimeout(self.timeout)

but it appears to have been commited as:

self.settimeout(self.timeout)

which deliver a no method error in case the timeout option is passed.