On Sunday 30 March 2008 12:19:58 Bjoern Schliessmann wrote: > Diez B. Roggisch wrote: > > if you have the chance, try & attach a machine with legacy rs232 > > port, and see if the errors still remain. > > Additionally, what kind of buffers does your device have? I'm using > pyserial to control a very "sensitive" device with nuttily > implemented buffering strategy. It has a "fast" and a "slow" buffer > which are filled in order, and no signalling to the outside sender > on how full they are. If the fast buffer fills the slow buffer > kicks in and requires less transmission rate. That may be how > characters could be lost with you. > > Regards, > > > Bjoern
That is a horrible device - have they not heard of RTS / CTS? or even XON / XOFF ? It is a wonder that you got that working without turning into an axe murderer. I don't think I could have. I have not been exactly forthcoming about the setup - the device in question sits on the LAN, so I connect to it via a TCP socket connection (in either client or server mode - seems to make no difference) . On the other side of the device, there is a serial port, and another PC is connected to the RS-232 side. This is the PC that runs a simple echo script that makes the occasional error, on its receive - I can see this because the transmission is paused when I see an error, and the two strings are identical on the two machines. As I mentioned in my reply to Diez and Castironpi - its not the device that is making the errors, as proved by a simple loopback. Another interesting statistic is that the number of lines "in flight" on the round trip machine1 > xport > machine2 > xport > machine 1 due to buffering varies between about 4 and about 26. So much for using it for real time control... - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
