I have a case structure for a dual syringe pump that will let me choose one syringe and aspirate as much as I entered in the control.
I also have a numeric tank indicator that displays the volume of fluid inside the designated side of the syringe.
The problem with that is if I have aspirate different volumes multiple times, the tank does not reflect the total volume that has been aspirated, but only takes the last value of aspiration.
I have a feeling that I will have to include the tank indicator inside some kind of loop, but I am not too sure which one.
The picture only shows the case structure of two syringes without tank indicator.
I assume you have a while loop that is looping thru your application. You'll want to create a shift register on the while loop that keeps track of the volume of liquid in each side. As you add/remove liquid, update the value in the shift register so that during the next iteration of the loop, you are working with current fluid levels.
You also should look at the event structure to handle when an action should occur. I made an example here for adding liquid to the syringes. When the button is clicked, both syringes are filled by the amount specified. If button is clicked again, the amount of liquid added is doubled (so you can see how to use shift registers to store syringe volumes). The values are initialized in the upper left at 0.