Hi all, i have a 3 way split range heating/cooling/chilled control where the heating is controlled between 200% to 100%, cooling 100% to 0%, and chilled 0% to -100% manipulated variables. I need to hold the MV at 0% until some temperature conditions are met before allowing the MV to move towards -100%.  

I currently have it set up where i pass either 0% or -100% into the MV_LoLim of the PID block, but when the conditions are met and the low range becomes -100%, the new scaling makes the MV bounce straight to -40%. 

Cheers  

Hi,

The below thread may help you

PIDConL how to start the controller with an initial MV?