Time measurement between two different signal sources

[Helmut E.]

I want to measure the time between the first rising edge signals of two different signal sources. Has anybody an idea what`s to do?. I can start counter 0 with the a signal on gate 0, but I have no Idea in which way I can stop it. (equipment PCI 6023E)

[ian_fung]

This might just gives you an idea of how to compute time different between two activations.

Note: Tick Count could be used

Modify this vi to suit your need.

regards

[Helmut E.]

Thanks a lot for the answer.

Unfortunately I must use the hardware-counter of the 6023E so I need gate or trigger signals. I`ve found a solution with an external electronic device (74221 and 7408) but it would be much better without the terrible solder activity...

Maybe anybody has another idea (or isn´t it possible with that device???)

Best regards, Helmut

[Filipe A.]

Hello;

The 6023E counter chip doesn't support triggered operations.
In case you know that both edges always happen on the same order, you can configure the counter of your device to do buffered event counting, and hook up both external pulses to the counter gate input.

Then, at every active edge, you will get a count value buffered in your computer. Since you know th timebase your are using on the counter source, you will have the elapsed time in between the edges.

Hope this helps.
Filipe A.
Applications Engineer
National Instruments

[Scott Seidman]

"Filipe A." wrote in news:50650000000500000061AC0000-
1031838699000@exchange.ni.com:

> Hello;
>
> The 6023E counter chip doesn't support triggered operations.
> In case you know that both edges always happen on the same order, you
> can configure the counter of your device to do buffered event
> counting, and hook up both external pulses to the counter gate input.
>
> Then, at every active edge, you will get a count value buffered in
> your computer. Since you know th timebase your are using on the
> counter source, you will have the elapsed time in between the edges.
>
> Hope this helps.
> Filipe A.
> Applications Engineer
> National Instruments

Depending on the logic family of the devices providing the pulses,
connecting them both
to the same counter gate input can be a very bad idea.
Much better to AND them together using hardware, and then pass the result
to the counter gate.



--
Scott
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[Helmut E.]

Thanks again for the answers.

The problem is, that I get more then one impulse from the starting light barrier (and the impulse is very short).
So my idea was, to connect the START and the STOP light barrier with monoflops (to extend the pulsewide of the starting edge to a time which is longer then the expected total time of the measurement), invert the STOP impulse and connect it by an AND to the gate of the counter (If anybody is interested I can give him the connection diagram).
It`s a time-consuming solution, but as far as I can see from your answers, the only way to solve this problem with that card (never buy low cost devices....)

best regards, Helmut

[Scott Seidman]

"Helmut E." wrote in news:50650000000500000083AC0000-
1031838699000@exchange.ni.com:

> Thanks again for the answers.
>
> The problem is, that I get more then one impulse from the starting
> light barrier (and the impulse is very short).
> So my idea was, to connect the START and the STOP light barrier with
> monoflops (to extend the pulsewide of the starting edge to a time
> which is longer then the expected total time of the measurement),
> invert the STOP impulse and connect it by an AND to the gate of the
> counter (If anybody is interested I can give him the connection
> diagram).
> It`s a time-consuming solution, but as far as I can see from your
> answers, the only way to solve this problem with that card (never
buy
> low cost devices....)
>
> best regards, Helmut

Wouldn't be my approach at all!! So long as you're venturing into
hardware you can

a) debounce your starting light barrier, if the waveform is suitable (get
a copy of Horowitz and Hill, "The Art of Electronics", and look up
debounce in the index

b)--Guaranteed to work, even if your waveform is unsuitable for
debouncing-- Use your light barrier output to trigger a Non-
retriggerable monostable multivibrator (i.e., one-shot), with a pulse
output that is longer than your light barrier event. The leading edges
will match up near perfectly. You can then use these pulses in many
ways-- to toggle a toggle flip-flop, for example.

Even the dedicated counter/timer cards sometimes don't directly support
the mode you would like them to operate in.

--
Scott
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