Writing Multiple Variables Being Monitored in Labview

[kitkat3333]

Hello, 

I am very new to using Labview and am needing assistance with writing mutliple variables to a Measurement file. I am attempting to monitor 6 voltage channels, 3 temperature channels, and  5 current (voltage) channels. I am attaching my block diagram (with the errors) and the file it writes. I am trying to get all values on the same spreadsheet with a time stamp.Currently I am receiving multiple untitled spreadsheets with instantaneous snapshots of my data.  Any assistance is welcome. Thanks so much!

[santo_13]

If your goal is to log data from DAQ channels, FlexLogger is a great fit. 

If your goal is much larger, where the DAQ is only a small portion, then there is value in you learning the workings of DAQmx and DAQ hardware to better architect your application.

[Kyle97330]

Can you post your actual VI instead of just a screenshot? Save it back to LabVIEW 2019 if you're on something newer.  

You're using a lot of Express VIs where the settings matter, plus we need full context on everything else going on.  We can't see that with just a screenshot.

Also, the error you're getting (-200279) means that your hardware buffer is full, usually because you're sampling fast but pulling your data slowly enough that it fills up.  It might be giving that error because your loop takes too long to run, possibly because you're running with highlight execution on, but if you get that even with it running normally then there may be other delays in your loop that make the buffer fill up.  It looks like you're trying to sample groups of 200 from a system recording at 2000 Hz, for a total of 10 times per second, is that correct?

[mcduff]

Use the built in DAQmx Logging feature instead of an express VI. The is a free plugin from NI to import TDMS files into Excel, so you can use that.

• Get rid of the Wait VI. Loop will run at the read speed, 200 samples/2000Sa/s = 100 ms.
• Are all of these modules in a cDAQ chassis? If so, you can make a single task and combine all three measurements together.
• What is the DAQ Assistant doing?
• Because you are using multiple starts, the data is not truly synchronized, but may be good enough for your application. (A single task solves this, otherwise you need some triggering to synchronize the starts.)

[kitkat3333]

Hello, Thank you for your feedback! I am attaching the 2019 version to this comment. Yes, my sample rate is 2000hz  and the sample size is 200. 

[mcduff]

Here is a quick mod to your program.

1. Your modules are in the same chassis, put them in the same task.
2. Use the logging feature.
3. Move the DAQ assistants to another loop, they are sending pulses. I never use DAQ assistant so not sure how it works, but its says they are sending highs and lows for 15s. How is your loop for acquisition supposed to run at 100ms if these are running at 15s?

EDIT: Set to Log and Read, should have been a constant not a control, like below