On Fri, 14 Jan 2005 23:25:21 -0500, Peter Hansen <[EMAIL PROTECTED]> wrote:
>engsol wrote: >> I didn't fully think through my application before posting my >> question. Async com port routines to handle com port interrups >> only work well if one has access to the low level operating >> system. In that case the receive buffer interrupt would cause >> a jump to an interrupt service routine.. I don't believe that >> Python provides that capabilty directly. The solution then would >> be to write a C extention? > >Maybe, but I doubt that you can or would really want to do this >with modern operating systems anyway. With DOS, and similar >primitive things, glomming onto an interrupt or hooking yourself >into the interrupt table was pretty easy. I don't think either >Windows or Linux is structured such that you just "write a >C extension" to intercept interrupts. Instead, you must write >relatively complicated drivers which have to be loaded at >system startup (more or less) and be tied into the kernel at >a relatively low level. Think "rocket science", at least in >comparison to writing a simple C extension. :-) > >> The suggestions offered by respondents to my original post >> were almost all of a "Use threads, and poll as needed" flavor. >> You're right...I need to learn threads as applied to com ports. > >At least on Windows, I'm fairly sure you can configure the >read timeouts so that you get behaviour on reads that for >all intents and purposes is about as good as an interrupt, >without the difficulties inherent in that approach, but >provided you are willing to dedicate a thread to the task. > >On Linux, it's possible the read timeouts capabilities are >a little less flexible (but I've only just barely glanced >at this area), but as I recall you were on Windows anyway. > >BTW, another post pointed you to USPP. As far as I know, >it hasn't been updated recently and, while I can't say how >it compares to PySerial, I believe it's fair to say at >this point in time that PySerial is the _de facto_ standard >way to do serial port stuff in Python. If it doesn't do >what you need, it's probably a good idea to at least point >that out in its mailing list so that it can be improved. > >-Peter Peter, thanks for the input...good advice. I took a look at USPP, and as you observed, it seems to be a bit dated. Actually, I've violated one of my basic rules: do it the simple way first, then determine what needs to be expanded, improved, speeded up, etc. Norm B -- http://mail.python.org/mailman/listinfo/python-list
