Op donderdag 12 december 2013 22:23:22 UTC+1 schreef Dan Stromberg: > On Thu, Dec 12, 2013 at 12:28 AM, Jean Dubois <jeandubois...@gmail.com> wrote: > > > On Thursday, December 12, 2013 12:20:36 AM UTC+1, Dan Stromberg wrote: > > >> On Wed, Dec 11, 2013 at 3:08 PM, Jean Dubois <jeandu...@gmail.com> wrote: > > >> > > >> I have an ethernet-rs232 adapter which allows me to connect to a > >> measurement instrument by means of netcat on a linux system. > > >> > > >> > > >> e.g. entering nc 10.128.59.63 7000 > > >> > > >> allows me to enter e.g. > > >> > > >> *IDN? > > >> > > >> after which I get an identification string of the measurement instrument > >> back. > > >> > > >> I thought I could accomplish the same using the python module "socket" > > >> > > >> and tried out the sample program below which doesn't work however: > > >> > > >> > > >> > > >> Sockets reserve the right to split one socket.send() into multiple > >> socket.recv()'s on the other end of the communication, or to aggregate > >> multiple socket.send()'s into a single socket.recv() - pretty much any way > >> the relevant IP stacks and communications equipment feel like for the sake > >> of performance or reliability. > > >> > > >> > > >> The confusing thing about this is, it won't be done on every transmission > >> - in fact, it'll probably happen rather seldom unless you're on a heavy > >> loaded network or have some MTU issues (see Path MTU Discovery, and bear > >> in mind that paths can change during a TCP session). But writing your > >> code assuming it will never happen is a bad idea. > > >> > > >> > > >> > > >> For this reason, I wrote > >> http://stromberg.dnsalias.org/~strombrg/bufsock.html , which abstracts > >> away these complications, and actually makes things pretty simple. There > >> are examples on the web page. > > >> > > >> > > >> > > >> HTH > > > > > > Dear Dan, > > > Could you copy paste here the code for your function I have to add to my > > "program"? > > > > This is untested, but it should be something like the following: > > > > #!/usr/bin/env python > > > > """ > > A simple echo client > > """ > > import socket as socket_mod > > import bufsock as bufsock_mod > > host = '10.128.59.63' > > port = 7000 > > size = 10 > > socket = socket_mod.socket(socket.AF_INET, socket.SOCK_STREAM) > > socket.connect((host,port)) > > bufsock = bufsock_mod.bufsock(socket) > > bufsock.send('*IDN?') > > data = bufsock.recv(size) > > bufsock.close() > > print 'Received:', data > > > > You might look over > > http://stackoverflow.com/questions/19918307/retrieve-file-information-located-on-a-different-application-server-using-python/19918706#19918706 > > for a more complete example.
Thank you very much for the example, the only trouble I'm having now is installing the bufsock module: wget http://dcs.nac.uci.edu/~strombrg/bufsock.tar.gz results in The requested URL /~strombrg/bufsock.tar.gz was not found on this server. Could you supply me the necessary installation instructions? kind regards, jean p.s. I'm using Linux/Kubuntu 11.04 -- https://mail.python.org/mailman/listinfo/python-list