PID dont start

Garrianz

Thanks. Do you mean i should use OB100 to set ModeActivate?

PID parameters is attached 

 I have to say that combination of PID parameters looks very strange to me. Can you please set manually some "normal" numbers. For example Proportional Gain 1, Integration time 10s, Derivation time = 0.  MAybe your strange PID parameters gives output always to a 0.

Mathematical equation of PID is very simple, If your output is going from 0 to 100, and your proportional gain is almost 50, plus in your example setpoint is 60 and reference is 13.4. Error is 46.6. Multiply that with 50... It just doesn't make sense. 

You need to be able to "feel" PID parameters, you get a feeling with time, but for beginning use mathematics. 

I attached my test example, make comparison whats different between our projects. 

Thanks again. I will try to set the PID parameters as you say.

I dont really know whats normal or not. But i should absolutely learn more about this. 

Anyways. After I put in the pid_compact block, i selected temperature. And then i run a pretuning wirh the parameters that tia portal set for me. Then a fine tuning that took me almost 5 hours. 

Garrianz

Thanks again. I will try to set the PID parameters as you say.

I dont really know whats normal or not. But i should absolutely learn more about this. 

Anyways. After I put in the pid_compact block, i selected temperature. And then i run a pretuning wirh the parameters that tia portal set for me. Then a fine tuning that took me almost 5 hours. 

 Let me know about results 

Unfortuntlaly i can not open your program, because I have V13. 

Allright. So i tested with:

P = 1.0

I = 10.0

D = 0.0

What is, and what should the 4 last parameters be?

And it seems like you were correct about the parameters. This time it started up automatically when setting setpoint above process value. Thank you so much.

It seems like the fine tuning dosnt work then... So need to find out how to set them manually.   

What is your process, what do you regulate and with what actuators. In the case you output is 100, how do you expect process value to be changed.

Point is your block configuration is OK, now you can play with parameters, usually that's job for commissioning 

I am regulating temperature in water, with an electric heater.

I will try to play with the parameters. But I do want to really learn this. Guess i have to google and youtube to get in depth about the parameters.

But I dont know what those parameters mean?:

* Derivative delay coefficient

* Proportional action weighting

* Derivative action weighting

* Sampling time of PID algorithm

Thanks again for all your help :)

Garrianz

I am regulating temperature in water, with an electric heater.

I will try to play with the parameters. But I do want to really learn this. Guess i have to google and youtube to get in depth about the parameters.

But I dont know what those parameters mean?:

* Derivative delay coefficient

* Proportional action weighting

* Derivative action weighting

* Sampling time of PID algorithm

Thanks again for all your help :)

 How do you control this electric heater?

• Case 1. -- >With discrete valve (one DO-> so simply ON/OFF)
• Case 2. -> Via some kind of proportional signal (AO where you send power of heater by some reference)

1.  You don't even need PID for this. I would just keep my DO always ON until temperature reach set value. Once temperature falls down to the SetPoint minus some hysteresis value I would turn it on again. SO your temperature is always in between setpoint and hysteresis value. If your case is Case 1. but you still want to use PID, I would stay with PI with large Proportional part and weak Integral part. You don't want that your PI/PID turn ON/OFF to many times your DO.

• Let's say you want to keep temperature at 40C, and current temperature is 20C
• I would go with Gain at least 5, Ti around 180sec, and cycle time minimum 10 sec.

2. IN this case which is more unlikely using PID is recommended. In order to give you some decent parameters you need to know: 

• how quickly your temperature can rise once your AO output is on max value. So you need size of tank compare to size of your heater.

Thanks again.

I am using PWM with solid state relay to control the heater. 

And you are maybe correct about just using on/off until it reaches the setpoint. But I want to learn more about PID, so ill try to make it work. But as you say, maybe PI is enough.

I dont know exact time to heat up, but it sure takes a while.. 

Anyways, I will start with the paremeters of P10 and I180 and try to adjust it :)