pH Control with two PID Data Objects

[boliver]

I wish to use two PID objects to control addition of 'base' and 'acid'.When 'acid' is being added 'base' PID output is driven to zero(and Auto switched to Manual).Voce a versa when 'base' is added.If Lookout had an equivalent of 'SET' command it would have been easy.What kind of 'expression' do I use to achieve this?Any help will be appreciated.

[Khalid]

Hi,

As you mention, the solution to the problem is to toggle the Automatic Enable parameter of the two PID objects at the right time -- one is TRUE (auto) while the other is FALSE (manual) and vice-versa. And of course have the Manual Ouput for both as 0.

So, what is the condition which makes either of these PID objects active? If we assume a simple Switch object (e.g., Switch1) to be commanding this, all we need to do is put the Switch1 object in one PID object and !Switch1 object in other for the Automatic Enable property.

You will replace this Swtich1 with whatever logical condition you have for toggling between the two objects.

Hope this helps.

Regards,

Khalid 🙂

[vriezz]

HI all,

I also doing the same project about the pH control for water treatment,i have the model,but I don't know how to draw an automatic PID controller, so that the valve can automatic on and off to control the the flow rate of the liquids, got any idea how to do an automatic PID controller to control the on off of the valve base on the set point?because I am beginner of labview, this problem make me headache. 

Regard,

Vriezz