Struggling for Terminalogy or Math to complete this

Hi Gents,

I need to make some changes to an existing Logix5000 program. Currently the machine fills with product based on time.This has to be changed based on weight now rather than time.

What I need to do is monitor the weight after the minimum feed weight has been reached and then "If the weight has not changed by X Kg in Y secs it must be full" and therefore we can advance the sequencer.

If someone were to describe this what would you call the parameters X any Y? Is there a mathematical function which would apply here?

Thanks for your help.

Technically you are waiting for the derivative of..

the weight as a function of time to be 0. I simpler way of saying this is that you want the rate of change to be 0.

Now forget the derivative stuff and make it simple. Use a FIFO or
queue that is 10 elements long. Put the current weight in the FIFO every 0.1 second if you want to monitor the change over 1 second. Compare the new weight with the weight that comes out of the queue. If the weights are different by less than say 0.01 Kg then go to the next step. You need to change the frequency and length of queue to meet your needs. You also need to pick a band for determining if the two weights are good enough.

Great. Peter has responded. I have the right man for the job!

So leaving the derivative aside. I require two parameters adjustable from HMI. A compare constant and a time.

These can vary quite a lot depends on quality of material been feed to the machine.

Could we still use a FIFO and change the frequency of loading the fixed FIFO array or no?