RS logix

hi

i have a timer(fuel loading time) for which the total loading time is to be set from the hmi panel.
This timer is to control the percentage of opening and closing of a flow valve. (for eg, if the time is 35 hours then corresponding %open-valve can be calculated).
My question is,
how to program when the operator increases or decreases the timer value in the middle of operation.that is...i want to add or subtract the extended or reduced time in the middle of operation, thereby my valve opening also changes


regards
chitra

If you are calculating the percentage open by volume and time then when your program detects a change it must subtract the currently filled amount an elapsed time from the desired full amount and the newly entered time. Use the remainders as inputs to a new calculation.

For example - if the fill process was started with a desired 1000 gallons and 50 hours then at10% into the process the time is changed to a total of 40 hours. Subtract 100 gallons from thee total leaving 900 gallons. Subtract 5 hours from the new desired total of 40 hours leaving 35 hours. Now recalculate based on thee 900 gallons and 35 hours.

If the newly entered time is just a new desired remaining time then you don't need to subtract the already elapsed time.

In short, a new fill process is beginning with the change of time.

I second Bernie. Also, after some time period, you may want to prohibit any changes if those changes become impossible to do in the time allowed.