Differences Btw. Counter Gate and Source Channels

[InergyLab]

I am working with a Flow Technology Turbine Flowmeter.  It has a 30mv-300mv sine wave signal.  I want to convert this signal into a usable pulse signal.  I am trying to look for information on connecting this signal to the counter channel of my PCI card.  What is the differences between the counter gate and source channels.  If anyone knows where I can get this information, please let me know. 

[WM_John_Weeks]

Hm. You seem to be asking two different questions:

1) Counter gate and source terminals.

It would depend on the exact hardware, but the source terminal would generally be the one that causes the counter to increment/decrement its count. The gate would control whether the source is allowed to do that. Some counter chips use the gate for more sophisticated counter control.

The best place to learn about counter/timer functions would probably be the NI-DAQmx Help that installs along with NI-DAQmx.

2) How to convert 30-300 mV sine wave to pulses. I take it that its the frequency of the sine wave that you're after.

This isn't a job for a counter. A counter requires a well-conditioned digital signal satisfying the rise-time and voltage levels of a digital signal.

You probably need to scan your signal with an analog input and then post-process it to calculate the frequency. There are a number of ways to do that- the simplest would probably be to look for zero crossings in the analog signal. I don't know Labview, but I bet there's a canned vi to do just that.

Message Edited by WM John Weeks on 12-13-2005 09:08 AM