COM performance

[Chuck Davis]

I am trying to write a serial communication routine using PowerBASIC.
Unfortunately, I can't get any kind of reasonable performance and am
looking for some suggestions. I am communicating with a micro-
controller at 38400 baud. Sending a 5 byte message and receiving
a 1 byte reply. I am only able to send about 70 messages per
second. With the VB program I was using before, I was getting
about 150 messages per second. When I use another microcontroller to
operate the interface, I get over 350 messages per second. The
theoretical maximum at this baud rate (assuming zero delays), is
about 640 messages per second. I know I won't come close to that
but 70 is way too slow.

I can post code if that will help - right now I'm looking for
some general suggestions about where to look for the problem.
I converted to PB with the idea that it would really improve the
performance, but I'm not seeing it at this point!

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[Russ Srole]

Chuck,

Better post some of the code. I've done a lot with PB and serial
and it works just fine.

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[Peter Manders]

Chuck,

are you by chance using the Powerbasic CC compiler, and PRINTing results to the screen?

If that's the case then you can stop searching, it's the PRINT statements that's holding you back.


Peter.


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[Eric Pearson]

Chuck --

Peter may well be right, but he neglected to add that there are things that can be done to speed up the console display. If that is, in fact, your program's problem, lots of people will chime in with suggestions.

-- Eric


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[Peter Manders]

Eric,

you're right, I was in a hurry and decided to let him verify first.
I knew lots of people would jump in once it was verified. Sorry for being short (my message that is).

Peter.


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[Chuck Davis]

The answer was similar to what has been indicated here. I was
using EZGUI and updating a few text boxes on the screen between
messages. Chris Boss suggested I remove all updates to the screen
and sure enough, when I did, the rate went from 70 a second up
to 340 per second. Still not as good as my microcontroller (which
has no UI of course), but certainly in the ballpark I was
looking for.

The reason VB did better was that I was only updating 2 items on
the screen in the VB program, versus 5 in this program. However,
even removing all the updates from the VB program netted only a
marginal improvement.

Thanks everyone!

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