Speed Tach- Time to Speed and Time to Zero Speed measurement and logging

[Timrdude]

I am trying to use a labview program one of my associates put together to measure TTS and TTZS. It uses 2) speed tach's 3V-1000 RPM, so 2 inputs (from motor drives) running simultaneous, coming on and off at different times. There are adjustments at near zero speed and near full speed to filter out noise and fluctuations. The TTS part works ok, but TTZS is hit and miss. Can anyone think of what might be causing this. I found the .VI's he saved on the drive, attached.

[Kevin_Price]

Not enough info to give useful help.

What does "works ok" mean?

What does "hit and miss" mean?

Is it a problem with capturing appropriate data from the DAQ device?

Or is it a problem processing the data after the fact?

If possibly related to data processing, you need to include some typical data.

It's good to include code.  But it's better to *also* provide a clear and thorough description to give us some context.

-Kevin P

[Timrdude]

It is related to data processing, the negative transition will not measure the same every time. I don't know lab view very well, so I am just looking for help in possibly fixing the way the voltage from the analog module is processed. Maybe like an oscilloscope you have to change to negative trigger to capture a negative going voltage to measure it.

[Timrdude]

See Labview data attached.

[Timrdude]

If you look at the attached Unit 1 and Unit 2 data collected, the second column (TTZS) should be like .350 seconds as column 1 (TTS) is. You can see the inconsistency in the numbers collected. 

[JimSDaavis980]

I am just looking for help in possibly fixing the way the voltage from the analog module is processed.

[Kevin_Price]

I only had time to look at the code briefly, and, well, in a word, YIKES!   For others reading this who *do* know LabVIEW, check out this little gem as an example:

                                      

Halloween's over so I won't share any other horrifying images, but suffice to say, this isn't code I would try to fix incrementally.  I'd call in the bulldozers, tear it down, and start over.  Sorry, I know that doesn't help you in the short term, but it's probably important for you to be aware that your end-result data is built on a pretty shaky-looking foundation.

About all I can think to recommend is to start very simply by working out the *algorithm* for TTS and TTZS in isolation from the rest of things.  Collect several files worth of representative raw tach data.  Then make code that can take this data and post-process it to calculate TTS and TTZS.  Expect to make several distinct versions of this post-processing code because some things you try won't work and you'll want to be able to revert back.

-Kevin P