This is a screenshot of the block interface at block call. It only shows a few values that are connected to tags.

I meant a screenshot of DB-Editor. You can do it by opening context menu of PID DB in technological objects folder (by right clicking), then "open DB-Editor".

There you have to activate the monitoring / glasses button.

"Config", "PIDCtrl" and "Retain.CtrlParams" structure should be expanded so all important values are visible.

I'm not sure if I understand your problem.

As long as Output is not 0 or 100, Output_PWM will always switch between on and off.

The ratio of on and off times is proportional to the Output value.

Example:

Your Retain.CtrlParams.Cycle is 1.0. This is the cycle time of PID-algorithm so every 1.0 second a new Output value is calculated. This tag is also used as period time of the PWM. So within 1.0 second the Output_PWM is switched on and off once (as long as Output is not 0 or 100).

Your Output is ca. 89. This means Output_PWM is 890ms on (89% of 1.0 second) and 110ms off.

When the cycle time of the interrupt ob (which means the time between two PID_Compact calls) is too high to switch Output_PWM at exactly these times, then PID_Compact will round this times and remember the error/rest that this causes to sum it up and correct it later. For example if your cyclic time of OB30 is 100ms, Output_PWM would be 900ms on and 100ms off.

Some additional hints:

- Your offline value of MinimumOnTime is 200 (it is not online so it is not effective, but just for your information). Usually only minimum on and off times that are smaller than the PWM period time Retain.CtrlParams.Cycle make sense.

- If you look at online values of tags with DB-Editor or watchtable you have an update time of several 100ms. So the ratio of on and off times you see at Output_PWM might be different than the actual ratio. You could use the Trace that is integrated in CPU 1200 to do a exact record of the tags and check if the values are like you expected.

- Documentation of the PID PWM with some information can be found here

https://support.industry.siemens.com/cs/ww/en/view/108210036/44734607627

I hope this information helps you. If not please describe your problem with more details.

Yes, you can make the Output value raise/fall faster by

- Increasing Gain

- Decreasing Ti

But it makes some effort to find a good combination of parameters manually (there are known rules that evaluate some characteristics of the process, google for "chien hrones reswick" if you want to learn more).

Did you try the integrated tuning of PID_Compact?

With Mode = 1 and enough distance between setpoint and process value (this method is usually used with "cold" process) you can execute pretuning: Output will make a step change to maximum value and the process reaction is evaluated.

With Mode = 2 and process value near setpoint you could execute fine tuning. Output will switch between two values so process value is oscillating (with little amplitude) around setpoint.

Both methods can also be started in commissioning editor. Alternatively you can use the Mode parameter.

In the PID documentation in TIA online help, there are more details described about the integrated tuning.