struglling to alternate pumps

[MaGoOoDy]

i am struggling to alternate between two pumps in my lift station project. ( this is my first project so far )


whenever i test the whole program and it is almost complete only i have found a mistake in the part of alternating the pump, it is not as the control sequence said .

i have attached the part of the program where i program the lead/lag switching, when i toggle the ( 7 days cycle trigger ) then the program stuck in toggling loop.


this the pdf of the program
https://ufile.io/l4zab

this is recording of my screen when i run the program online.
https://ufile.io/fwz1q




do i am making this in proper way ?

guys, how do you handle this alternating ( lead/lag ) between part ?



attached the control philosophy

 

[OkiePC]

The needs of your logic can be boiled down to a basic flip flop.

There are at least a dozen different ways to solve it.

The method you are using is probably being foiled by the fact that the trigger bit is true for more than one scan.

I don't have access to programming software right now, but basically, you need to ensure that you only execute a "flip" once and not flip and flop right back to where you are.

Here is a link with many examples of various methods of flip-flops. They are based on Microlgix, so if you are using a SLC, you'll need to substitute ONS with OSR instructions where used in the examples.

http://www.plctalk.net/qanda/showpost.php?p=438416&postcount=12

 

[labeledas]

just from a quick glance you need to reset your trigger B3:0/7 I couldn't download video but I assume when you toggle you are leaving that bit on so what happens is

bit is on N7:3 = 0 Pump B is set to run fires one shot on rung 5 n7:3 is set to 1 but if B3:0/7 is still true rung 2 executes rung 0 becomes false on the EQU so ons resets

Rung 4 resets N7:3 to 0 and cycle starts over you need to turn B3:0/7 off

 

[Lare]

You toggling bit stays on and after it there is EQU which makes bits to alternate 0/1. It might work if you move EQU blocks on networks 1 and 3 after ONS.

Why you are setting bits B3.0/6 and B3.0/8?

 

[MaGoOoDy]

even though if the toggling bit stayed toggled it should be only applied only for one scan since i am using one shot after the compare instruction.

 

[MaGoOoDy]

The needs of your logic can be boiled down to a basic flip flop.

There are at least a dozen different ways to solve it.

The method you are using is probably being foiled by the fact that the trigger bit is true for more than one scan.

I don't have access to programming software right now, but basically, you need to ensure that you only execute a "flip" once and not flip and flop right back to where you are.

Here is a link with many examples of various methods of flip-flops. They are based on Microlgix, so if you are using a SLC, you'll need to substitute ONS with OSR instructions where used in the examples.

there is no link appear to me in your post ...!!

 

[labeledas]

no because you EQU makes the rung false thus resetting the ONS

 

[Lare]

even though if the toggling bit stayed toggled it should be only applied only for one scan since i am using one shot after the compare instruction.

N7:3 change value between 0 and 1, ONS give one shot on network NW0 and 2 every time, when N7:3 changes.

 

[MaGoOoDy]

i tried to find Flip flop examples to see how could i manage them to choose the lead pump but i don't know how to implement them in my
code ...

help ..

 

[azarobi]

Why the bit N7:3 fluctuating in the video? It is the one determining the Lead/Lag and whether the operation is in Auto or manual it should not be changing the decision so fast based on your description of operation and as far is I can tell it is the one causing the whole fiasco.

 

[OhmsOutlaw]

Why the bit N7:3 fluctuating in the video? It is the one determining the Lead/Lag and whether the operation is in Auto or manual it should not be changing the decision so fast based on your description of operation and as far is I can tell it is the one causing the whole fiasco.

Probably because the program needs to update which pump is lead pump. I haven't watched the video.

Is the cycle trigger (B3:0/0) on for more than 1 scan? If so, that would cause what you're describing.

 

[OhmsOutlaw]

Here's how I would do it. This is an example of a flip flop, which was mentioned by OkiePC.

 

[DSMR]

That flip flop will always unlatch the output bit on the lower branch. So there is no way for it to latch the output on.

 

[OkiePC]

That flip flop will always unlatch the output bit on the lower branch. So there is no way for it to latch the output on.

Yes...
try this modification:

 

[DSMR]

Or use the same tag one shot in each branch...