Re: Serial Communications - Lost Event

"Completion of write" is a moment when all data from the app buffer is
comsumed by the driver. The driver can keep the data in its internal buffer
while it's being sent, though, after the write is completed.

You can use WaitCommEvent/EV_TXEMPTY, to detect when the last byte is sent
to the hardware, but again, it may still be held in FIFO.

"krisk" <krisk@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
news:1CED0C92-C539-47DD-B8AB-4E80AD55F5D9@xxxxxxxxxxxxxxxx
> Hi All,
>
> Thanks for your replies. Didn't mean to sound like I was deriding Windows
> or anything (I really do think it's wonderful, just a bit difficult to
> code
> for sometimes..lol).
>
> What I'm trying to create is a com port monitor that works well with the
> UI
> messaging loop. I want incomming data to result in a message posted to my
> UI. I also want a message posted when outgoing data has been transmitted,
> so
> that I can monitor response times. My immediate application is for a
> bootloader, but I'd like to be able to re-use the code later for real-time
> serial port monitoring and test applications.
>
> So I don't want the communications code to serialize reads and writes
> behind
> the scene and I don't want reads and writes affecting the timing of each
> other, so they need to operate completely independently of each other. I
> have not seen any examples on the web that support this.
>
> Jochen, regarding your comment:
>
>> No. It just signals if there is enoght space in the drivers buffer to
>> receive new data. Currently there is _no_ sign which will show you that
>> data was sent...
>
> The WriteFile API documentation states:
>
> "The event specified in the OVERLAPPED structure is set to the signaled
> state upon completion of the write operation."
>
> I guess I'm assuming that 'completion of the write' operation in the
> context
> of a serial port means when all of the data has been transfered. Is this
> not
> the case?
>
> Still, I'm wondering if I'm violating some undocumented internal OS
> constaints by having two different overlapped I/O events active on the
> same
> port handle. Is this a legit thing to do? (BTW, I've also tried
> duplicating
> the port handle and using two threads, but I run into the same problem).
>
> Oh, and I am using manual reset events.
>
> Regards,
>
> Kris
>


.

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