some sort of PWM
arindam  [8 posts]
16 year
hey, i donot know if this is the right place to ask this but i am stuck at a problem.
  i am sending a value out through your PARALLEL port module.
  and i wish to implement some sort of PWM(pulse width modulation).
very siply i wish to set a value
SetVariable "data", 2
  sleep for a while

' SetVariable "data", 4
    in vb script followed by a Parallel port modulue.. but am unable to implement the sleep function
please hel me out..
Anonymous 16 year

You can't really sleep in the VBScript module as that would stop processing. As the pipeline is essentially an infinite loop (i.e. grab an image, process it, then grab another, etc) adding a sleep would cease all execution which is usually not desired. So instead you can use the SetTimedVariable to cause the variable to change value after X number of milliseconds. Your script would look something like:

period = 2000

step = GetVariable("step")
if step = 0 then
  SetVariable "data", 2
  SetVariable "step", 1
  SetTimedVariable "step", 2, period
if step = 2 then
   SetVariable "data", 4
   SetVariable "step", 3
   SetTimedVariable "step", 0, period
end if
end if

which would case data to oscillate between 2 and 4 with a period of 2000 seconds. Note that usage of step and setting it to 1 and 3 which are dummy steps where nothing is done.


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