FIFO queue setup

[drbitboy]

Here is another thread doing something similar: https://www.plctalk.net/qanda/showthread.php?t=134096

 

[jlenahan2]

Okay so I did incorporate the unlatch bit prior to my post and it is unlatched when the ffu.eu is active. but I am not unloading immediately after I load. Maybe I'm not trying to use the FIFO as it is designed but I am wanting any station calls to immediately go to queue, acknowledge the call, and just hold.
As a separate subprogram, I've got state logic that will progress through the steps to load hopper (turn on pump, set valves, etc for the particular hopper). At the end of fill cycle, I'm wanting the last state to unload the next position in the queue (if none active, go to hold state) and then jump back into the filling program at step 2 (state 2) or whatever.

My logic is literally the exact same as @ASF except i am using a less than instruction of a float source to a set point instead of station[1].call and station[2].call XIO that can be toggled. It is probably prudent to mention this is rslogix500 so my ffl en XIO to the latch bit is a branch under the actual FFU. The latch is also indirect addressed to the N7 value so the logic does seem to work fine to latch and unlatch the calls directly. It's just that if all less than float to set points are true upon simulation, the fifo just never increases position. Latches get set though so how can I set the latch based on the ffu.en working but the fifo not move position and store the value?

Rather than a low level sensor, this is a loss in weight type batch scale. So I have a high level sensor for full and weight for the batch weights dropped per cycle. Since I do not want to run completely empty before refilling, I want the station call to be a certain multiple of the batch weight. So if there are only say 3 batches left in the system, let's refill. And as a reference, hoppers on the order of around 15 cubic feet or around 500ish lbs of material.

 

[jlenahan2]

Also, these are work type tanks and not vacuum receivers that have a flapper valve and normally fill on time. I need to fill until full, much like filling a silo

 

[jlenahan2]

Well i shouldve looked for any recent posts before responding, @Drbitboy, found your 4 station example in the thread you linked. Let me chew on this and see what I can get from it before I go any further here. Thanks

 

[drbitboy]

so how can I set the latch based on the ffu.en working but the fifo not move position and store the value?

Post your code, (print to) PDF is best