From the mailing list, October 1999:
>
> The DataAvailable event handler is probably the problem. It can,
and will,
> allow other DataAvailable events to trigger from inside the
DataAvailable
> Handler.
That, is disastrous.
(James pencils it into his list of pending nasty bugs.)
Yours
James Milne
REAL Software, Inc
So this bug has been present as far back as 1999 and it's still with
us to this day. Has RS decided to let go of serial port support?
I've spent more time in serial port programming with RB than I have
with any other subject. Almost all of that time has been spent
banging my head against a wall trying to figure out what is going on
with DataAvailable. It seems every application I have that requires
the serial port reveals some other quirk or bug. Some things I have
considered "bugs" may be due to my misunderstanding of how the DA
event works. A definitive guide, included in the Help files, would
help tremendously. And I'm not alone with DA questions. The list is
chocked full of others with similar confusion.
This week's problem is response time.
I have an RB app that receives 42 bytes of data (at 115.2kbaud) and
responds with a 39 byte reply. The data I receive repeats every 1.25
seconds. The reply must be sent within 20 milliseconds from the
received packet.
In my DataAvailable event, if all I do is read the buffer and then
send a fixed string back out the serial port, it is delayed from the
received packet anywhere from around 2 ms to 80 ms (yes, 80
milliseconds).
What must I do to insure that this Quad G5 can send a reply within 10
ms or so?
-Richard
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