joe T

Do you need to decide during each loop iteration whether you'll be turning the laser on or off? If so, what you need is labview real-time, so that you can perform computations during each iteration of a timed loop.

On the other hand, if what you need is a relatively slow on-off modulation of a fast blinking laser (with 2 states of "blinking" or "off"), let me suggest the use of a 555 timer circuit in astable mode, controlled by the 555's 'enable' pin. You'd use your parallel port to control the enable pin.

http://en.wikipedia.org/wiki/555_timer_IC

Never underestimate the power of the 555!

I need to decide in each iteration whether it's on or off. This is done by reading from a file that contains 0's and 1's, in some order. 0 means off - 1 means on, so a 555 won't help me there. I also need in each iteration to read back from the parallel port, which has one pin connected to a photodiode circuit. Is Labview Real-time a different software?

Thanks

Joe

Joe,

It might be important for us to know why you need such an accurate wait between iterations. If this is not just an excersize, then maybe we can help you with the real goal you have in mind.

That metronome is only intended for rough timing and that's why it doesn't go to smaller increments. Data acquisitions are clocked to a "Timebase." The minimum timebase will depend on the hadware you have. For instance my E-series DAQ card has a maximum rate of 1.25MSample/second. So I could easily take readings at 10kHz, 100KHz and perhaps 1MHz depending on howmany channels I need to sample.

It is possible to do custom work at these speeds, but usually we just pull out some application specific vi or function that does it for us. This way we never have to write code that operates that low down in the system. Not that you can't do it, but it would be very untypical.

So tells us what you are up to.

Mike

Thanks for your reply,

I am activating a laser pointer that is connected to a standard parallel port. The activation is by giving it 5V via the parallel port and then 0 - thus the laser is blinking.

I need it to blink at about 10Khz.. and until now I managed to work at most at 1Khz, as stated in my previous message.

So I guess that a VI that I will need is one that gives one of the data pins of the parallel port the value "1" for 0.1 ms and then "0" for 0.1 ms and so on.

thanks!

Joe

Hi,

I'm new to labview so this should be pretty basic stuff...

I'm trying to create a loop with a delay between each iteration:

1. The minimum waiting time between iterations that I could accomplish is 1 ms (The metronom image requires integer mltiples of 1 ms only?). How can I get a faster time between iterations? (Say - 0.1 ms)

2. How do I make sure that the waiting between iterations is not affected by the actions taken during this iteration?

Meaning - if in one iteration, the computer does nothing, I want it to wait exactly the same amount of time as in another iteration, in which it performs many calculations.

Hope I made myself clear,

Thanks

Joe