suggestion for pH adjustment alogrithm

[godpaul]

Hi, here is my code for judging pH and adjusting pH value using state machine.

I only finished the cases when pH >7.5, I havent done the cases for pH<7.5.

I understand its very akward because it lacks of real control alogrithm; But I really dont know how to program a controller to relate time and pH value together.

In the VI, you will see I adjust pH by opening/closing relay board which further drives valve to open/close to let electrolyte flow out/stop.

We will do experiment to determine the time for opening/closing valves... It will invlove a lot of work and I am aware of it.

Any suggestion regarding programing technique, bug, etc will be appreciated. Thank u!

p.s the BEi delay VI is provided by one of NI forum adminstrators.

[godpaul]

I found one problem myself,

in the case of ''start DAQ'', I want the VI to take measurement for 5 seconds and stop, then it can calculate mean value. The mean value will be used for later cases.

The problem is the start DAQ keeps running, when 5 seconds is reached, the mean pH value is calulated but the Vi is stilling reading data...

[fromm8 · Accepted solution]

  Hello

 -You could wire the stop input in the DAQ assistant and the stopped output to the end condition of the loop to stop the acquisition after 5 seconds. 

Regards