how to do fifo in labview?

[devchander]

Hi Nishant,

If i understood it right, it give data of each channel - row wise ( since you said ' if the End Channel no is 4 and samples/ch is 10, then it will give 5 rows and 10columns' it means channel data is 'row wise' as each row corresponds to one channel's data)

Ok look at the Modified Vi i Have attache.

it should do the trick

( note if it still does not work, just see if i am indexing out the row data correctly)

regards

Dev

[Nishant]

Hiii, Dev

               Here i ve done the modification in your VI, but one big mistake is i am erasing the data which is coming inspite of the 1st record, can you suggest me the solution for that, bcoz if i am selecting the 0th row, it doesnt do that, it is erasing the last column's last n records, which i dont want, here i am sending you the vi in which i am writing 2 files, 1 normal and 1 for the FIFO(which is not happening),so please modify, if youo can.

Thanks,

Nishant

[devchander]

Hi Nishant,

You have missed out on two things.

1. The shift register logic to realise FIFO.

2. The true condition insert and delete logic.

Just incorporate these two features as i have shown in the VI titled '2026_ScanMultAD_32chs_filewrite13_1.vi' that you will find in the previous posts.

It will work

Regards

Dev

Message Edited by devchander on 12-19-2005 06:01 AM

[winterishere8]

I've pasted a screenshot of my VI. This should help you build it. Hope this helps.

[Nishant]

Hiii, Dev,

             Y'day after i mail u, i realise the logic about inserting and deleting, and if suppose i ll insert ur logic of shift register what it will do is, as number increases from the shift register,the number between 2 timestamps(mean if s.r. count is 0 the time stamp is at next sample, if s.r. count is 1, time stamp is left out in the 1 sample, if 2, left out in 2 samples, thats why i ve delete the shift register logic, but as u told i ll again try it differrently with shift register logic.

Thanks,

Nishant 

[Nishant]

Thanks Max,

               I ve try to implement wat u ve shown me but there is a problem in the vi, when trying to flush the buffer and getting the data output,it shows the error as shown in the figure.

Thanks,

Nishant

[Nishant]

Hii Dev,

           Can you please tel me that how much time while loop is taking in the LV to execute? is it exceeding 10 msecs, or is it below that? please answer me asap, i am so keane about that, coz i am taking the data from PCI card and writing it to the excel sheet, it has the resolution 15msecs, and we require the min of 10 msecs. so please answer me.

Thanks,

Nishant

[winterishere8]

Ok, can you post your code here ? I need to have a look at it because mine works perfectly fine. I bet there is a mismatch in the type of data.

[Nishant]

Hiiii,

          Here I am sending you the code.

Thanks,

Nishant

[winterishere8]

Couple of things.

1. In the case TRUE statement, u need a dequeue. You've used a get status. We need to dequeue the elements if the buffer size is more than what you specified.

2. In the case FALSE statement, you need to wire the queue refnum, and the error. False statement denotes that your buffer is not full and you continue to enqueue the elements.