9237

[Stagsden]

I am trying to log strain gauge and load samples at one per second, but I am getting far too many points.

I have looked at other examples, but I just cannot slow down the rate.

I am using a cDAQ-9172 rack with and 9215 voltage input and a 9237 strain gauge module.

Each module has 2 channels.

This is turning into one of those LabView issues which take longer than it should.

Can someone please look at the attached vi and see where I am going wrong.

The rate input does not seem to have much affect.

What rate should I set the task to in MAX. I am using continuous samples.

Thank you for any help,

Stagsden

[MarkGrot · Accepted solution]

You are seeing extra samples because you aren't acquiring data at 1 sample/s but rather 1,612 samples/s.  The NI 9237 has a set of discrete sample rates (50kHz / 1..31).  Your task is coercing the sample rate up to the next valid value, 1,612 in your case.  This coercion is normal but with delta sigma devices the step to the next valid value is larger than other devices.  The sample rate limitations are listed in the NI 9237 Specifications in the "Understanding NI 9237 Data Rates" section and data rate range in the "Specification" section.

You can determine your actual sample rate by querying the sample rate (though not in MAX).

Message Edited by MarkGrot on 02-05-2010 01:16 PM