Measuring the time taken between values received from tags

[Stuart Wilson]

I am measuring the times (in seconds) of 3 production sequences; x, y and z. I can get the values of x and z from the plc via tags configured in the DSC module, however I can not measure y straight from the plc. I would like to calculate the time taken between x stopping and z starting in order to give me the time span of y.

Is there a way of programming the Tick Count (ms) function to start counting once I have stopped receiving the value of x, and to stop counting once I have started receiving the value of z?

Any example code would be greeeattly appreciated.

Many thanks,

Stuart

[GerdW]

Hello Stuart,

surely there's a way 🙂

Take the actual time when you stop getting x values and take again the actual time when you start the z stage. Subtract the first from the second and you get the y-time.

[Stuart Wilson]

Take the actual time when you stop getting x values and take again the actual time when you start the z stage. Subtract the first from the second and you get the y-time. Hi GerdW, thankfully I managed to work out the maths of obtaining this time (i would be worried if i didn't), however I am not sure how to 'take the actual times' using LabVIEW code, especially to specify when one tag STOPS measuring and the other tag STARTS measuring. What functions or commands do i use to achieve this?? Do you have any example code I could have a look at? Your time and input is much appreciated! Stuart

[unclebump]

This is a perfect case for why we need events based on DSC tag value changes without having to write code. You could use dynamic events and use the tag values to trigger them. Or just read the tags in a loop and use some code with it. Attached file is 7.0 format.

[Stuart Wilson]

Excellent UncleBump, thankyou. Just a quick question though.. i take it the true-false, false-true inputs determine whether the vi takes the time when the value stops recording, or when it takes the time when the value starts recording??? For this reason, does the initial 'x' element of the read tag have to go on top of the array of tag names, and the 'z' element go on the bottom?? I'm a little confused which way round this applies to my example. Many thanks for your support, Stuart

[unclebump]

Yes, the x tag name would go on top in the array. I assumed you were looking at boolean values.