Re: rs232- [C]

From:

"Scott McPhillips [MVP]" <org-dot-mvps-at-scottmcp>

Newsgroups:

microsoft.public.vc.language

Date:

Sun, 25 Jun 2006 13:48:47 -0400

Message-ID:

<u#G3E$HmGHA.4064@TK2MSFTNGP02.phx.gbl>

Robby wrote:

However, what is going on, is that once I read the string the first time,
immediately after, it does another read, as you stated, I guess Windows stops
reading once it read the whole serial rs232 buffer!

So, basically I find myself with two successive reads and then VC++ hangs. I
don't know if it is because I put a break point on the read statement??????

Anyhow, scott, do you have any ideas on what can be causing this!

Please get back....if you can!

Hope to hear from you!

I told you in the previous answer about how the serial read decides when
to return. If there is no data coming in it returns after the timeout
you specify in SetCommTimeouts. If you don't specify this then it will
never return. It sounds like that's where you are at.

Since serial data comes in at its own pace, and you can never be sure
you will get all the data you expect in one read call, and the serial
read likes to block for the timeout duration, it is usually necessary to
do serial reading in a separate thread from your GUI. For now you can
probably get by using one read call with a generous timeout, but
consider moving to a serial thread later to make things more responsive
and robust.

--
Scott McPhillips [VC++ MVP]