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Message-ID: <001701c18a34$23c6ad00$1400a8c0@alex>
From: "Alex Oleynikov" <alex AT compuweigh DOT com>
To: <djgpp AT delorie DOT com>
References: <001f01c18995$b8043360$1400a8c0 AT alex> <3C22E937 DOT 2E7D1336 AT is DOT elta DOT co DOT il>
Subject: Re: Memory accessing performance
Date: Fri, 21 Dec 2001 10:28:28 -0500
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Reply-To: djgpp AT delorie DOT com

Eli Zaretski wrote:

> How does this update process work?  That is, how do you talk to the device
> itself?  Depending on how you do it, the actual bottleneck might be
> communicating with the device, not updating 100KB of your program's
memory.
>

To the PLC the program talks via a serial link implementing the Modbus
protocol over it. I am not worried about loosing performance in this
particular case, since PLCs normally don't poll data too often. But the
application is rather complex and does a lot of other things like talking to
a digital weight indicator @ speed of 19200 baud etc. (it's basically a
bulkweighing scale controller certified by the US government for accurate
weighing in grain industry - loading ships, rail cars, trucks etc.). So my
general concern is just to use a better code overall.
BTW, in conjunction with that I have another question. I did some profiling
of the application and analyzed the generated output. The profiler's
sampling rate was 0.0555 seconds, but as I said there are certain events in
the program that happen at much higher rate (e.g. polling digital I/O and
controlling the gates). Is there a way of increasing the profiler's sampling
rate?

Thanks for helping me.

Bye,
Alex