Delay in NI 9205 Input module

[Chrispy555]

Hello:

I am using a NI 9205 input module card in a cDAQ9188 chassis. In labview there is a delay between the signal change and the change in labview. For example. I have a flow meter that is outing 1.5V to the module. When I increase the flow, the meter outputs 1.9 volts right away, but Labview has a delay of about 20-30 second before the reading changes. As time goes on, it gets worse (up  to 2 minutes) I've rebooted the computer and chassis and the delay decreases, but then it just gets worse again. I've also swapped out modules and it does the same thing. I'm thinking its a computer problem as when we tested it in our computer lab, it was working fine. All other modles in the 9188 are working fine (temperature, digital and analog output cards). I believe there is a buffer  in the 9205, but all I want to do is just output the data in real time.

I have attached a screen shot 

Anything I can check before I format the computer and reload labview?

Thanks

Chris Paulusse

[GerdW]

Hi Chrispy,

no, there is no buffer in the module. There's a buffer in the DAQmx driver software...

- What is the loop iteration time in your VI? You have set a sample rate of 1Hz for your analog inputs and you read just one sample per DAQmxRead. If the loop iterates to slow you will fill up the internal buffer in the DAQmx driver.

- Did you read the help for DAQmxTiming? What is the purpose of setting the "Samples" input to 1000 in case of continuous sampling?

- Why do you convert your array with measurement values to a cluster - just to unbundle that cluster? Why not use IndexArray instead?

- You can do all that gain/offset correction either with array math (you know LabVIEW functions are often polymorphic?) or by using DAQmx scaling...