James,
The FFU (FIFO Unload) is the instruction that becomes your "machine station" start-up controller. It controls WHICH station starts next, and it should also control WHEN it starts. FFU must have a trigger bit that goes on and off for each station that is to be started.
For a FIFO operation, you do 4 steps (1) logic that sets up the Load, (2) FFL, (3) logic that sets up the Unload timing, (4) Unload that controls the machines.
I don't understand why in your Main Ladder Subroutines, you put the FFU (Unload) BEFORE the Load. Logicaly, the Load MUST occur first, so reversing them confuses me. It must work that way, but your PLC has to scan all the way around once past Sub 3 and get to Sub 4 before anything else happens. I fixed that for you once, but I see you ignored the hint.
Basically, your Lad 5, Rung 002, FFU now controls WHICH machine station starts next, but it does not do an adequate job of controlling WHEN it starts. I think it will step through all 12 machines without pausing to wait for a water fill. You have 3 instructions on Rung 002 that do essentially the same thing, where one of them is all you need (along with missing logic that looks at your Water Fill timers to see when the next one is done). Unless B3/7 is a bit that goes on then off when it is time to run the next machine, then I see no UNLOAD logic that is tied to the Water Fill timers.
I am not very good at explaining this, but I will try again. Look at Lad 5, Rung 000. When N7:19 = 1, your Station 1 will be given permission to start. But I thought you did not want Station 1 to start UNLESS all other stations either were not running, or had finished with water fill?
Yet here it is, Station 1 will start whenever it (at some earlier time) put in a start request, regardless of what the other stations are NOW doing. That defeats one of your original goals (controlling WHEN the machine starts happen).
The FFU (FIFO Unload) is the instruction that becomes your "machine station" start-up controller. It controls WHICH station starts next, and it should also control WHEN it starts. FFU must have a trigger bit that goes on and off for each station that is to be started.
For a FIFO operation, you do 4 steps (1) logic that sets up the Load, (2) FFL, (3) logic that sets up the Unload timing, (4) Unload that controls the machines.
I don't understand why in your Main Ladder Subroutines, you put the FFU (Unload) BEFORE the Load. Logicaly, the Load MUST occur first, so reversing them confuses me. It must work that way, but your PLC has to scan all the way around once past Sub 3 and get to Sub 4 before anything else happens. I fixed that for you once, but I see you ignored the hint.
Basically, your Lad 5, Rung 002, FFU now controls WHICH machine station starts next, but it does not do an adequate job of controlling WHEN it starts. I think it will step through all 12 machines without pausing to wait for a water fill. You have 3 instructions on Rung 002 that do essentially the same thing, where one of them is all you need (along with missing logic that looks at your Water Fill timers to see when the next one is done). Unless B3/7 is a bit that goes on then off when it is time to run the next machine, then I see no UNLOAD logic that is tied to the Water Fill timers.
I am not very good at explaining this, but I will try again. Look at Lad 5, Rung 000. When N7:19 = 1, your Station 1 will be given permission to start. But I thought you did not want Station 1 to start UNLESS all other stations either were not running, or had finished with water fill?
Yet here it is, Station 1 will start whenever it (at some earlier time) put in a start request, regardless of what the other stations are NOW doing. That defeats one of your original goals (controlling WHEN the machine starts happen).
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