"Nick Timkovich" <prom....@gmail.com> wrote:
> I've been working on a program that will talk to an embedded device > over the serial port, using some basic binary communications with > messages 4-10 bytes long or so. Most of the nuts and bolts problems > I've been able to solve, and have learned a little about the threading > library to avoid blocking all action while waiting for responses > (which can take 50 ms to 10 s). Ultimately, this program will test > the device on the COM port by sending it messages and collecting > responses for 10k-100k cycles; a cycle being: > 1. tell it to switch a relay, > 2. get it's response from the event, > 3. ask it for some measurements, > 4. get measurements, > 5. repeat. > Later I would like to develop a GUI as well, but not a big issue now > (another reason to use threads? not sure). > > The overall structure of what I should do is not very apparent to me > on how to efficiently deal with the communications. Have the main > loop handle the overall timing of how often to run the test cycle, > then have a thread deal with all the communications, and within that > another thread that just receives data? My main issue is with how to > exchange data between different threads; can I just do something like > have a global list of messages, appending, modifying, and removing as > needed? Does the threading.Lock object just prevent every other > thread from running, or is it bound somehow to a specific object (like > my list)? What I have been doing for similar stuff is to modularize using processes and pipes instead of queues. This allows you to have the communications in one process, in which you hide all the protocol issues, and allows you to deal with the resulting data at a slightly higher level of abstraction. Such a structure also makes it easier to have different user interfaces - command line or GUI, it does not matter as the commands and responses to the comms module can be standardised via an input and output pipe to and from the comms module. HTH - Hendrik -- http://mail.python.org/mailman/listinfo/python-list
