Re: using serial port using APIs

The baud rate is 9600 and there are only 15 bytes.

It is the time takes between the mscomm1.output (TxData) command and the
polling device actually getting the data that is the problem.

It just takes too long.

Also I cannot find any help searching for vb setcommconfig.

Is there an API that will wait for receive data and then inform the
programme that there is data available?



--
JamesT


"vbexp" wrote:

> What baud rate are you using? How many bytes in the response?
>
> It takes 7 ms to send a byte at 1428 baud. Usually, it takes 10 bits total
> to send a byte(the byte itself+start and stop bits). So if you are sending
> at 38400 Bits/Sec, that is 3840 Bytes/Sec. Each byte takes 260 us, for 7 ms,
> the response can be no more than 26 bytes.
>
> For an API approach, check newsgroups for "vb SetCommConfig"
>
> > I would also like help on making the programme multi threaded so that the
> > comm portion can be started as a separate thread so that the main
> > programme
> > can get on with other things while waiting for a poll.
>
> VB6 is not multi-threaded except for ActiveX EXE's, but even that may not be
> suitable(global variables are not shared between threads). I recommend that
> you design your software in such away that it returns quickly from the
> OnComm event. You can't show a MsgBox in OnComm event. If you have to, defer
> it to a Timer.
>
>
> "JamesT" <JamesT@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote in message
> news:A6FC7773-0B28-4302-A777-F89D7DE0E397@xxxxxxxxxxxxxxxx
> >I would like to use the Windows APIs to communicate with a Device connected
> > to the serial port. Can any one suggest good reading material that uses
> > VB6.
> > Most of what I have found gives examples in C++.
> >
> > The Programme is polled every 20ms by the device and the PC has to build
> > the
> > response ( about 7 ms) and reply very quickly. Using the MSComm control is
> > too slow as the reply seems to take about 20ms to get to the device after
> > the
> > MSComm write command.
> >
> > I would also like help on making the programme multi threaded so that the
> > comm portion can be started as a separate thread so that the main
> > programme
> > can get on with other things while waiting for a poll.
> >
> > Please help
> >
> > --
> > JamesT
>
>
>
.

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