Alcorn Mcbride V+ series, User Manual

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6-20 Advanced WinScript Programming
after the external event will not be able to execute until the external event is
finished processing.
The Processor Scans Events like a PLC
ScriptOS is a multi-tasking operating system. This means that it can do several
things at once. Well, it can’t actually do several things at once, but it can do
many, many things in one frame. The processor executes events one sequence
at a time. This process is similar to how a Programmable Logic Controller
works.
ScriptOS performs the following processes in order, once per frame:
1. Process Incoming Serial Messages
2. Process Input Changes to see if there are any sequences that should be
marked to start
3. Process State Variables to see if there are any sequences that should be
marked to start
4. Parse Through List of Running Sequences
Execute any event that matches the current frame time
5. Process Output Changes
6. Increment the Frame
Let me give you some examples of how this affects you:
If you turn on an output, it won’t actually go on the instant the event is
processed. It actually turns on just before the end of the current frame, along
with any other output changes. This means that if you were to turn on an output
and then turn it back off again on the same frame, the output would never
actually turn on at all. The last commanded state of the output before the end of
the frame is used.
OutputDoesntActivate
Label Time Event Data1 Data2 Data3 Comment
00:00.00 On output1
00:00.00 Off output1
00:00.00 On output1
00:00.00 Off output1
00:00.00 On output1
00:00.00 Off output1
00:00.00 On output1
00:00.00 Off output1 Never came on
This example probably is a little more useful. If you have an event that tells
another sequence to start, it does not actually start it, but rather, it marks it for
execution. This means that if you start a sequence that is before the one you call
it from, it will not begin execution until the next frame, whereas if you start a
sequence that is after the one you call it from, it will begin execution on the
same frame.
SequenceA
Label Time Event Data1 Data2 Data3 Comment
00:00.00 On output2