LabVIEW
Trying to logg my data to excel with a specific time interval
Hello, this is my first post here. Sorry for my bad english.
I have a daqmx program that you can regulate with PID, and the results should bee logged to a excel file, with timing when its logged and the output data. But i am having trouble with the timing. I use the elapsed time express VI to decide the timing. And the Write to mesaurement file express VI to write to excel.
What i want is that you can decide how often it should be logged, like every 1 second or every 10 second. But when i sett it to 1 second the logging data in excel shows that it logges every 1,1 seconds or soo. And this is to inaccurate.
This is where my logging system is. Elapse time shuts of the logging every 1 second but in the excel file the timing is every 1,1 seconds or so.
This is what i get out of the excel file. Time and date from start to stop. But what i also could like is a second row where its says 10-20-30-40 or 1-2-3-4-5 so its easier plotting into a diagram.
Shouldn't i use the Express VI?
Hi/Hey King,
This is where my logging system is. Elapse time shuts of the logging every 1 second but in the excel file the timing is every 1,1 seconds or so.
So something in your code needs more than 1s, and so your loop takes ~1.1s to iterate.
Shouldn't i use the Express VI?
In general that is a good idea!
But what i also could like is a second row where its says 10-20-30-40 or 1-2-3-4-5 so its easier plotting into a diagram.
I guess you need one more column (instead of a row).
Either add that data as additional value for logging - or create your own logging routine…
Why do you read data from DAQmx with setting "n samples" and wire "-1" as number of samples? You didn't set any samplerate in your DAQmx task!
Why do you read the samples as waveform? Why do you convert that waveform to a single/scalar value using an ExpressVI?
Why don't you read just one sample using the "1 chan 1 sample" mode of DAQmxRead?
Why do you apply a Median filter? Are you sure you don't want to average (aka Mean) here?
Why do you use that "funny" PID routine instead of the AdvancedPID function coming with LabVIEW? (A PID function should not depend on the iteration count of the loop its placed in…)
Btw. it isn't recommended to use LLB nowadays with recent LabVIEW versions. Use a plain folder and a LabVIEW project instead!
Hey King,
What do you mean here? i have set samplerate to -1 so that daqMX determens the samplerate itself.
Wrong. Please read the context help of DAQmxRead to learn which input you have wired!
This i am unformiliar with. I figured out where to set these settings, but there was way to many of them and my program crashed, what is the right one?
Like this:
The PID block i used came with the basic program, but i have now changed it to the advancedPID.
Wrong. This is not the AdvancedPID function, it's the "PID Advanced Autotuning"…
what is LLB? are you talking about the project library?
See your attachment from your first post: that is a LLB file!
LLB were used in ancient LabVIEW versions to allow bundles of several VIs with filenames larger than 8.3. Nowadays you don't need them anymore: place all project-related files in a folder, including the lvproj file!
Could you show me how?
Like this:
How do i get this to write to excel? and i want a start stop function on it, so i dont logg all the time.
Looking for something like this:
Hi King,
to handle differently formatted values within a row you need to do the formatting on your own:
The FOR loop with a random function is representing your 3 data items you want to log…
On your VI:
You read just one sample from DAQmxRead: why did you choose the waveform datatype? Why not read a scalar DBL value and get rid of that last ExpressVI?
Hi King,
I don't understand where i decide what heading goes over what value,
You decide that by the order of data items in the BuildArray part!
When you build an array of "PID sp", "PID cv" and "PID output" values, then your header line should match that order…
i want to chose when to start and stop my logging,
Use a case structure to enable/disable the logging code…
