how to tune the PID of temperature controller???

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How to tune the PID of temperature controller to become from a PID control function to a very simple on / off control function???? can i set it as P=100 I=0 D=0???????
 
PID equations produce an analog output (CV, 0-100%)

If you have an On/Off device that you are trying to control with PID, you want to have the device ON for a fraction of a time-slice equal to the CV.

For example, you may have a time period of 60 seconds. If the CV is 50%, you would want to have the DO ON for 30 secs, then off for the remainder of the time. CV = 0 means that the DO doesn't come on, CV=100 means that the DO is ON all the time.

Tuning these kind of loops, then, is little different than tuning a regular analog loop, except that you mey need to play with the time period a bit to ensoure that you have a tunable loop. Too long, and the PID may alternate over/undershooting. Too short, and the DO may not have enough influence on the PV.

But once you get the time base about right (order of magnitude), do like you would with any closed loop: Set a manual CV and let the system stablize, change the CV and note the time lag between the SP change and the PV change, measure the slope of the PV change, etc., and get the tuning constants.

Whether you have integral or derivative will depend on the type of system.
 
Without knowing the details of the controller you're using, I can't give you specific values, but a high proportional gain value and a suitable deadband to prevent oscillation should do it.

You want the value obtained by multiplying the P gain by the error (difference between setpoint and measured temperature) to be large enough to command maximum output.
 
Too short, and the DO may not have enough influence on the PV?

Allen Nelson said:
PID equations produce an analog output (CV, 0-100%)
Tuning these kind of loops, then, is little different than tuning a regular analog loop, except that you mey need to play with the time period a bit to ensoure that you have a tunable loop. Too long, and the PID may alternate over/undershooting. Too short, and the DO may not have enough influence on the PV.
Usually the faster the update rate/output period the better. Explain.
 
you might need to set opening limit to 25%, 50% etc for the control valve depending on set point for better results.
 
On-Off

hi
most of the temperature controller manufactures if it's not all of them made the selection of the control type On-off/p/I/PI/PID through a software parameter.What you need to do is just select the proper value for youe control type in this prameter.Just review your manual and you will find it.
BR
 
yes it will work when it is other way around just fill in -100


however i think it will be better to write if too high open ,if too low close.
 
If you are talking about a generic PI(D) controller, with an analog CV output, and controlling a two state (on-off) or three state (Heat-Off-Cool) device, you should really use time proportioned outputs.

There are a few things to consider with discrete temperature loops; one being that most often, you do NOT want to rapidly cycle the control elements on and off.

The most common range of Time Proportion Outputs (TPO's) is probably from about two seconds to 10 seconds with typical systems.

For a two state (on/off) system, say you have a free running 10 second timer, and a PID that generates 0 (no heat) to 100 (Max heating). When the timer expires, look at the CV output of your PID loop.

Use the CV output to set the 'ON' time of your heating element based on the current accumulated value of the timer. In the above, if your CV is 40% when the timer expires, you would check against an accumulated time of less than 4 seconds to drive the output:

Output_On = (Timer.AccTime < (40% * TimeBase))

So the output would be on for 4 seconds, off for 6, then the CV is resampled at the next timer start.

Often, there is a lower limit, or minimum on time as well to prevent rapid cycling, around 0.1 to 0.5 seconds. In this case, anytime the CV is less than 5% for example, the controlled element just stays off.

Hope that helps a bit.
 
got problem fill in the FB58 siemen s7 300

i got a problem to fill in the FB 58 temp self tune using siemen s7 300. my sensor is pt 100. problem with pid block TCONT_CP
 
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