Automatic Tanks Switch Over

wanher3 · Jul 10, 2019

Hello,

I need help with impleting the logic for Automatically switching Tanks.
Basically I have two tanks, each with its own valve and transfer pump.
Operator select a primary tank1 or tank2 and initiate the tank transfer. But in the event that the operator also makes a secondary tank selection, when the primary tank goes empty, the program needs to automatically switch from transferring tank1 (pump 1) to transferring tank2 (turning on pump 2).

How can this logic be implemented ?

Thanks

sparkie · Jul 10, 2019

Use a boolean (bit) to determine which tank is active.

0 - tank 1 active
1 - tank 2 active

Your logic to switch between tanks will control this bit to determine which tank to activate. When the tank is activated, it will open the valve and run the pump.

Now, you have one tank that is primary, and if the other tank isn't primary, then it is secondary.

If primary tank empty -- > activate secondary.

James Mcquade · Jul 10, 2019

which plc?

the first thing you need to do is write down what you want.
you have given us the basics, now you need to write down in detail what the process is. lets look at it another way.

do the detailed write up for only 1 tank.
its empty, fill it, stop filling - more details that this.
the write up for the second tank is the same.

so you now have tank 1 and 2.
now do the write up for switching from tank 1 to 2.

when you write down the steps, pretend you are the plc, do the instructions make sense? if it's not on paper, you can't execute the instructions, because that is in your head.

post your work and we will help.

james

sparkie · Jul 10, 2019

James Mcquade said:
which plc?

the first thing you need to do is write down what you want.
you have given us the basics, now you need to write down in detail what the process is. lets look at it another way.

do the detailed write up for only 1 tank.
its empty, fill it, stop filling - more details that this.
the write up for the second tank is the same.

so you now have tank 1 and 2.
now do the write up for switching from tank 1 to 2.

when you write down the steps, pretend you are the plc, do the instructions make sense? if it's not on paper, you can't execute the instructions, because that is in your head.

post your work and we will help.

james

Fantastic job breaking this down.

James Mcquade · Jul 10, 2019

i find that when you work with someone and start with the basics, they will tell you if they already know things, rather than talk above their heads and really confuse them to the point they no longer want to work with you.

this is the way i do things, may be boring to a lot of folks, but it helps the beginners and is a starting point for everyone.

james

Elcan · Jul 11, 2019

You may need to add several timers. For example, you don't want to close a valve while or right after the corresponding pump stops pumping. You stop the pump, wait a few seconds then close the valve. The same way, you open the valve and then, after a second, you start the pump.

Automatic Tanks Switch Over

wanher3

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sparkie

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James Mcquade

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sparkie

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James Mcquade

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Elcan

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