Can I use the 6508 to monitor a digital waveform

[Jim001]

I need to capture a signal and convert it to a waveform. The following points apply:

1. Cards available are 6508 6052 and 6733.

2. possible waveform would be a varying PWM signal. sampling rate 100kHz

3. Capture time could be up to several minutes

4. Any data should not be lost in this period

5. Analog or digital capture would be ok

I would appreciate any help on this. Which card would be most suited?

[SachaE]

Hi Jim001,
I think we've just been speaking on the phone about this, but for the rest of the community :
the digital lines you have available are all static lines, so you can't do an accurate waveform grab - it would be software timed.
The best solution is to use the counters (which if you're the person I was speaking to on the phone today you can't do because you have some custom hardware which limits you to digital or analogue inputs since you could go up to 12V and need to attenuate the signal.
You can use the analogue inputs however, and there are vi's such as the Pulse Measurements.vi that will let you know the dity cycle etc.
Here's the vi's I sent you (if it was you!), along with a modified algorithm for duty cycle measurements since you said the Pulse Measurements.vi seemed a little slow.
Don't forget that you are now dealing with very large data sets. This could have been avoided with the use of the counter timers, and still remains the best option if you can wire onto them (they're 5V TTL so don't go over that!)

Hope that helps

Sacha Emery
National Instruments (UK)