pH Control with two PID 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]

You can use the 'Automatic Enable' datamember and write a false to it to turn off the PID. And the value specified for the 'Manual Output' datamember will then be used as the output of the PID (which you can make 0 in your case).

Hope this helps,

Khalid