Barry Kirk
Lifetime Supporting Member
I'm in the process of converting over a temperature loop from Step 7 to Portal.
The old Step 7 program uses FB58 TCONT_CP for the PID block.
In the old program the manipulated value could range from -100% to +100%. If the value of the manipulated value was over 0, than I ran the Q_Pulse output straight into the output to drive a solid state relay that fired my heater element.
If the value of the manipulated value was less than zero, than I sent it to some code that fired a cooling fan.
With Portal, the TCONT_CP claims to be only useful for pure heating or pure cooling loops and the manipulated value lower limit seems to have a minimum value of zero.
Are there any blocks for heating/cooling loops in Portal, or is there any way to get around the limitation of a manipulated value lower limit minimum value of zero?
The old Step 7 program uses FB58 TCONT_CP for the PID block.
In the old program the manipulated value could range from -100% to +100%. If the value of the manipulated value was over 0, than I ran the Q_Pulse output straight into the output to drive a solid state relay that fired my heater element.
If the value of the manipulated value was less than zero, than I sent it to some code that fired a cooling fan.
With Portal, the TCONT_CP claims to be only useful for pure heating or pure cooling loops and the manipulated value lower limit seems to have a minimum value of zero.
Are there any blocks for heating/cooling loops in Portal, or is there any way to get around the limitation of a manipulated value lower limit minimum value of zero?
