FOR LOOPs for delays instead of PAUSEs

Archiver

Hi all,
I am interested in using FOR loops instead of pauses so my program
can do other things while it waits (or delays) such as poll for user
input. I went to Tracy's site and found out some execution times for
various for-loops. I just want to know how I can make use of those
statistics. Any help would be appreciated. Of course, I understand
that the actual delay time depends on the program nested in the for
loops. I just want to know a "ball park" way of creating for loops to
give the delay I want.

Thanks,
RP


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Archiver

RP -

I used a hybrid of looping and pausing for an
industrial controller. While moving through a timed
recipe, a loop would call a subroutine to check for
remote stop signal, call another subroutine to check
for a interlocked status signal, increment a counter,
check if time is up, then pause for something like 248
milliseconds. Time was up when 4x the desired number
of seconds was in the counter. Stopwatch testing over
a 60-second step indicated whether the operand given
to PAUSE needed to increase (to a max of 250, or 1/4
second) or decrease (to accomodate execution time for
the subroutines, counter increment, and if statement).


One good thing about this was that the PAUSE command,
usually limited to 65.535 seconds, could reach 4 1/2
hours by using a WORD counter and a BYTE operand, the
latter for a 1/4 second pause.

One drawback: I am only paying attention to critical
inputs every 1/4 second. This was okay for a project
that is looking for an input state, but may not be if
a momentary button press must be monitored. Changing
from 1/4 seconds, where the PAUSE operand is less than
250, to 1/10ths (100 ms), 1/20ths (50 ms), or 1/50ths
(20 ms), say, makes exact timing on a larger scale
less easily achievable.

Bob Pence



--- rpsu279@y... wrote:
> Hi all,
> I am interested in using FOR loops instead of pauses
> so my program
> can do other things while it waits (or delays) such
> as poll for user
> input. I went to Tracy's site and found out some
> execution times for
> various for-loops. I just want to know how I can
> make use of those
> statistics. Any help would be appreciated. Of
> course, I understand
> that the actual delay time depends on the program
> nested in the for
> loops. I just want to know a "ball park" way of
> creating for loops to
> give the delay I want.
>
> Thanks,
> RP
>
>
> for i = 1 TO 1 : next
> [noparse][[/noparse]825]
> .
> 330
> .
>
> for i = 1 TO 2 : next
> [noparse][[/noparse]1582]
> .
> .
> .
>
> for i = 1 to 10 : next
> [noparse][[/noparse]7691]
> .
> .
> .
>
>
>
>
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Archiver

>Hi all,
>I am interested in using FOR loops instead of pauses so my program
>can do other things while it waits (or delays) such as poll for user
>input. I went to Tracy's site and found out some execution times for
>various for-loops. I just want to know how I can make use of those
>statistics. Any help would be appreciated. Of course, I understand
>that the actual delay time depends on the program nested in the for
>loops. I just want to know a "ball park" way of creating for loops to
>give the delay I want.
>
>Thanks,
>RP

It can be quite a chore to get exact timing if you are really down to
the wire on speed. However, if the program is just waiting for user
input and has to do a couple of quick tasks in the meantime,it can be
paced with short pauses or NAPs.

loop:
' check user input
' check machine status
' update outputs
pause 48
goto loop

If the tasks take 2 milliseconds, then the 48 milliseconds makes the
total time add up to 50, which is usually fast enough to respond to
user input. If you need to run the loop in a more precise time
interval, you need to be more picky about counting the microseconds.

-- Tracy