How can you change the aquisition speed?

[nicholas03]

I have a vi that gets temperature as a function of time from a thermocouple (MCC). I want the temperature to be sampled at different times not just every 5 seconds. How?

Message Edited by nicholas03 on 10-07-2007 04:43 PM

[nicholas03]

Message Edited by nicholas03 on 10-07-2007 04:45 PM

[Dennis_Knutson]

Don't link to images that are located on your hard drive. You need to attach them to your post with the attachment button below the message body.

You can have any single point acquisition rate that you want and you can change it as it runs. Just look at the example program you attached here.

[jaced]

Hi Nicholas3,

I just want to verify that I understand your issue correctly. You are acquiring temperature data and want to slow you acquisition down, I am assuming that you are using a thermocouple and thus are using DAQmx to read said thermocouple. If this is correct the easiest way to accomplish this is to insert a wait into the acquisition loop. The wait functions are on the Timing palette. This will hold the loop for the specified number of milliseconds before allowing it to iterate. There is an excellent shipping example titled Cont Acq Thermocouple Samples-SW Timed.vi within this example this method of holding the loop is used. as illustrated in the screen shot from the example.

What is happening is in the while loop a call to the DAQmx Read VI is made, pulling a single temperature sample from the DAQ device into PC memory. The while loop will then wait until the user specified amount of time has elapsed before iterating and pulling the next temperature sample from the DAQ device.

Thanks

Message Edited by jaced on 10-08-2007 03:31 PM

[nicholas03]

I am using a MCC driver and hardware. USB-TC. I've created this so far. I want the temperature to be taken and plotted faster.

Message Edited by nicholas03 on 10-14-2007 12:02 AM

[Dennis_Knutson]

There is nothing in the LabVIEW code itself that is controlling sample rate. You are running as fast as possible. I don't see any parameters that you are passing to the Call Library Function Node that would set the sample rate either. You should look through the shipping examples.driver from MCC to see if there is a function to set a faster sample rate. You should also contact MCC for questions about their hardware and software. They have a users forum and phone/email support.