Learning A PID Loop

Have this assignment and Im pretty green on PID..

A START pushbutton is connected up to start the program, which should immediately cause the temperature to rise to 318K. When the specified temperature is reached, closed loop control should control at that temperature for 2 minutes, and then the temperature should decrease to 308K, and run at that temperature for 1.5 minutes. Temperature should then increase back up to earlier stated high temperature, and the system should cycle between those two temperatures for the same time periods as stated above. A STOP pushbutton should be connected to stop the program at any point in its cycling and turn off heater; if START is again pushed, the cycling should begin again and run indefinitely (or at least until the STOP is again pushed).

Connect a fan blowing on the heater to an output and only energize that fan whenever the temperature should be driven downward.

Use the 1746-NIO4V if using the AB SLC 500. The "K" in the temperature is in reference to the Kelvin temperature scale.

Is there a know starting point for the contact block>for PID

I know 308k=94 F
318k=112.

I know I have to dial it in setpoints gain freq.. etc... Is the a well Know default starting point? Then I will use a gret than and less than statement fot highs and lows..

Any sugeestions.... Thanks

welcome to the forum ...

where are you going to get the input (temperature) signal from? ...

Then I will use a gret than and less than statement fot highs and lows..

Click to expand...

this is a school assignment - right? ... are you REQUIRED to use an actual PID control block - or just the Greater Than and Less Than instructions that you also mentioned? ...

Some of your control are covered by "ramp and soak" - can you look for that in your book?

learning PId loop(cont)

Im getting a signal through a RTD. Signal goes up. Temperature goes down.. Im required to use a PID control block. So greater than or equal is out.. Just wanted to know any general numbers to use. Or what the train of thought in this process is. Ramp and soak would be easy, but we dont have those devices.. Just using analog inputs and outputs... Thanks