-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On Fri, 22 Oct 2010 00:00:03 +0100 MRAB <pyt...@mrabarnett.plus.com> wrote:
> On 21/10/2010 21:05, Todd Walter wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > > Hash: SHA1 > > > > On Thu, 21 Oct 2010 17:03:58 +0100 > > MRAB<pyt...@mrabarnett.plus.com> wrote: > > > >> On 21/10/2010 15:57, Todd Walter wrote: > >>> -----BEGIN PGP SIGNED MESSAGE----- > >>> Hash: SHA1 > >>> > >>> On Thu, 21 Oct 2010 00:07:58 +0100 > >>> MRAB<pyt...@mrabarnett.plus.com> wrote: > >>> > >>>>> > >>>> [snip] > >>>> > >>>> The docs for 'sendto' say: > >>>> > >>>> """The socket should not be connected to a remote socket, > >>>> since the destination socket is specified by address.""" > >>>> > >>>> Could your problem be caused by you binding the socket to a > >>>> source port, so it's going out both to the bound port _and_ the > >>>> one given the binding? > >>>> > >>>> Have you tried using two sockets, one outgoing and the other > >>>> incoming?, > >>>> > >>>> BTW, your code for handling the response doesn't cope with it > >>>> coming in a bit at a time. It loops discard any previous data > >>>> from the previous iteration. > >>>> > >>>> Also, it's more Pythonic to say: > >>>> > >>>> while '\r' not in respo > >>>> ... > >>> I haven't bound the socket to a remote port, as I read it; it'sp > >>> bound to a source port (192.168.10.2:2260, the local machine) and > >>> just transmits to an address with a port glommed onu sn > >>> (192.168.10.1:2002, the PLC). > >> [snip] > >> What I meant was that you're using 'pcSocket' for both directions > >> and using .bind on it. > >> > >> Try creating two sockets, 'pcInSocket' and 'pcOutSocket', and bind > >> only pcOutSocket. As it turns out, I must use only one socket. I have to use a fixed source port as the PLC will respond to that port. If I transmit using .sendto with an unbound socket the source port is picked at random making listening for the response impossible. It was my understanding that there could be a many-to-one relationship between sockets and ports but an attempt to recv without a bind throws an error and an attempt to bind to an already bound port throws an error. I thought the socket operations worked on the buffer so why does multiplexing fail? It shouldn't care how many listeners there are, it should just read the information off the wire and throw it somewhere everyone can read it. Is there a way to specify the source port for a transmission without first binding to it? - - Todd -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.16 (GNU/Linux) iEYEARECAAYFAkzBkV0ACgkQwnknPuQqPIM/4ACeKDGYAUJPdBjyGV2Iu6l/5bA1 X/MAoIWDOvnMhdA0NHXLo2Mv1Nm8kkZZ =4t/0 -----END PGP SIGNATURE----- -- http://mail.python.org/mailman/listinfo/python-list
