RSLogix PIDE split range

[Zaheer]

Hi there,

I have to control a temperature (at the outlet of a two stage heat exchanger) with two different heating water lines; 65°C and 95°C. Both have control valves installed.
I want to use the 95°C water only if the set point is greater than 65°C.
Any thoughts how can I imlement this? I am using RSLogix 5000. By the way I am not sure if split range is true term for this.

Thanks in advance for any help.

 

[widelto]

Use two PIDE, same setpoint for both, one PIDE enable at a time.
If setpoint is bigger that 65 use one if less use the other.

 

[Zaheer]

Thanks widelto.
But I think I did not explained my problem very well.
In any case I want to use the maximum energy from 65°C water.
So if the set point is 80°C, the control valve for 65°C should be 100% open, and the rest of the energy should be taken from 95°C water.

So I will use the 65°C PIDE always with SP range 0-65°C.
and 95°C PIDE only if SP is greater than 65.
What should be the SP range for 95°C PIDE, 65 to 95?
With the same SP for both PIDEs?

 

[widelto]

Zaheer, when your SP is greater that 65, then PIDE1 is off and valve1 is 100% manually, use move instruction to open your valve.
At this time PIDE2 is working and controlling temp thru valve2.
When SP is less than 65 PIDE2 is off, valve 2 is off you can close it manually if you want it, use a move instruction and temp is controlled thru valve1.
I see no problem.

 

[Zaheer]

Thanks Bill. I understand now.