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7/4/2014 11:49 PM | |
Joined: 1/28/2009 Last visit: 9/10/2024 Posts: 6849 Rating: (1365) |
Hello, Standard PID controller from libraray inside TIA Portal is customized for S7-1200.It is complex to handle but it is standard.Search the forum for more tips like THIS regarding PID Compact.
If you are looking for a simple PID controller, you should work a lot to make it look like a standard function and applicable in a practice in industry.You can try the formul utilized in "Engineering Control" section in OSCAT library.You have access to SCL source codes and re-create those formula in SCL for S7-1200.You can start from FT_PIWL .OSCAT library is developed for STEP 7 and you need STEP 7 to view the formulas. I hope these comments help you Hamid Hosseini |
7/5/2014 12:12 AM | |
Posts: 5225 Rating: (1192) |
The advice from our friend Hamid Hosseini is very solid. If you have doubts on the background or wish to rather develop the coding yourself, I recommend you have a look at the velocity format of the PI controller. This [LINK] will help. The last formula in the explaination (discrete velocity form) should be easy enough to adapt into code. A caution though.. think about putting this code into a timed interrupt OB (OB30) to ensure you have a stable update time. When reading input words or writing output words within this OB, make sure to use ":P" as part of the call. Please ask if there are more that needs detailing. Greetings. w |