FIFO Load/Unload

[TCL28]

I am new to RS Logix 5 - can anyone help me with a little example of a FIFL and FIFU code. When I make an input I want to capture the data and put it in a FIFO. I followed the example in the help but my data only seems to load in one bit one time.

Thanks,

TCL

PS - I searched this site for FIFO questions but I could not find anything but I apologize in advance if this is a repeat.

 

[Rube]

FIFO stacks load and unload words, not bits. Hopefully that's what you meant. And they do that one at a time, not in bulk.What exactly are you trying to do?

 

[TCL28]

I am trying to capture the number of seconds and a time stamp on when a certain input it turned on and off. Like a detailed histogram. I want to move the time and number of seconds the input was on into a small FIFO of about 10 places since this input is usually only switched on 5-8 times a day. At the end of the day I will write the information in my excel spreadsheet for trending and start over the next day.


Thanks for the help,

TCL

 

[Rube]

You'll have to capture the time, hour/minute/second, and each part of the time will be a word; one word for hour, one for min., etc. I take it your elapsed time in secs comes from a timer? If so, that data will have to be captured, before the timer resets, and moved into a word as well. Now you have four words. You'd probably be better of using several COP instruction rungs versus FIFO stacks (actually you'd need four stacks).

Good luck

 

[RSL]

What Rube said sounds right on the money.

FIFO is a pain. Use Copy instead.

RSL

 

[TCL28]

I am pretty new to this but what Rube said is on the money - I have four words. How do I use the copy to capture the data?


TCL

 

[Rube]

How many Snapshots of these four words might you CONCEIVABLY see before Resetting? Take that number and multiply it by four, one for each portion of the snapshot. That answer is the number of free integers you will need for your COPy instructions to use. Using one word as an example and six instances of that word, set up a ladder that copies from the #5 integer to #6, then #4 to #5, then #3 to #4 and so on. This will set your most frequent value in your smallest integer as well as sequence the snapshots. Do the same four your other three captured words. You will be able to display these integers on an HMI or look them up online in the Data Tables.

 

[TCL28]

Thanks Mark - and I love the quote about Automation!

 

[Rube]

Glad to be of help--let me know if I can be of more.