Problems accurately counting pulses

[Ether]

Eric,

The pulse width would affect your ability to reliably detect all pulses with software polling.

How wide is the pulse width at the highest anticipated pawl speed? Have you measure this on the 'scope?

The pulse width would be affected by both pawl speed AND how deeply each tooth engages the switch ("dwell", as we used to call it back in the days before electronic ignition).


~

[ubermeister]

We will try some of these solutions tomorrow morning. Glad to know that LabVIEW and the cRIO are not the cause of our problems, that we just didn't know the right blocks to use.

Ether: The pulses are approximately symmetrical, equal time on and off. The point of transition is a little higher than halfway up a tooth, to account for the pawl not falling down all the way for very high ratchet speeds.

I wasn't looking for timing on the scope, I was just making sure that every pulse was counted and clearly defined, eliminating electrical or mechanical failures as the cause of our problems. Hence, I don't remember the timing.

I believe that the fastest the pawl will ever go back would be 5 teeth in about 1/2 second, or 20 hertz. It's not nearing any unreasonable speeds, though it seems that the cRIO can handle very fast speeds using DMA.

Joe: This single channel counter seems useful. Will it be obvious to a programmer where to find it?

Thanks very much for the responses, I learned a lot about programming today