Alcorn Mcbride V+ series, Руководство пользователя

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6-22 Advanced WinScript Programming
the remainder of the previous guests presentation. He wants to be able to press
the button and have the presentation start over from the beginning.
Restart
allows this.
This is a nice feature. But let’s say that no-one is watching the presentation (It’s
off), and a thirteen year old boy walks up to the kiosk. He starts the
presentation, gets bored within 0.0000015 of a second and out of curiosity
pushes the button again, to find that the presentation starts over. In fact, if he
pushes the button over and over as fast as he can, he can get the frog
presentation to “rap”. This is oh so much more exciting than the presentation
itself. Now people are staring.
Restart Lockout allows you to set a number
of frames that the sequence will not restart in. This allows serious guests to be
able to restart the show when they don’t want to watch the last half of the show
first, and it prevents your and my favorite milk shake globbering, paint chipping
teenager from rapping the frogs.
Preventing Glitches
Glitches occur when an input of a Show Controller receives a voltage close
enough to the maximum to turn it on, or low enough to ground to turn it off,
even though no person or device intended the signal to do so. This can be
caused by noisy signals or a noisy device transmitter (people are automatically
noisy transmitters in the case of buttons). There are two ways to reduce the
effects of glitches.
The Purpose of an Input or Button
If it’s possible to do so, make each input signal serve only one purpose. If some
computer or PLC somewhere is sending pulses to an input to tell the Show
Controller what to do, the Show Controller could become confused if one pulse
is supposed to tell it to do one thing, and two pulses another. This is possible,
but confusing and dangerous. Likewise, a button on an OCC panel which the
operator is supposed to press several times to mean different things can cause a
problem because the person could accidentally press it the wrong number of
times, by not pressing it solidly each time. You can afford to buy a few more
$90 Allen-Bradley buttons.
I realize that I recommend using one button for Daymode/Nightmode. This is
due to the way that DVD Players react to being spun up and spun down. I’m not
concerned with glitches for Daymode/Nightmode because this button is pushed
when there are no guests in the theatre and likely the building.
Check the Input Again
Even if your inputs only serve one purpose, they can still glitch and cause
inappropriate behavior. The best way to confirm that your input went on, off, or
pulsed, is to check it again. If there was a glitch, it is unlikely that the signal is
still glitching when you check later. Here is an example that checks 10 frames
into a 15 frame pulse to make sure the input is still on.
StartShowNow
Starts show on ½ second Input 3 pulse (Start trigger: