Wonderware Intouch 2012 tank filling

[hepios]

Hi guys,
Im newbie, so please don't punch me for my lame question
I have three tanks and mix tank and they have text field for litres. My problem is, that I don't know how to count and fill my red mix tank with sum of three tanks above.
As I said, Im newbie so Im using just easy window scripts.
When I fill the three tanks with some litres of liquid I click on the button mix and these three tanks are going down -> and in this time I want to continuous fill the mix tank with the sum of that three tanks (which are going down).
In tank1,2,3 Im using easy script:

if valve1 == 1
then
tank1 = tank1 + 1;
endif;

with 1msec.

Please! Any ideas with usage of these simple script ?
Something like if mix == 1 then mixtank = mixtank + ????...

Thank you!

 

[robertmee]

Is this a simulation or real world app? Cause in the realworld you can't fill and remove at the same time without independent measurements.

If for simulation, mixtank = mixtank +3 unless one of the tanks is empty, then +2 or +1 or +0.

So Mixtank = Mixtank + (Tank1>0) + (Tank2>0) + (Tank3>0)

 

[hepios]

Thank you robertmee, it works!
Its just a simulation

Thank you!