I see this is a very old post but I'm hoping to revive it.  I am wanting a function that you can input a running time of a piece of equipment and the running average would be calculated to a maximum of X hrs. to help operators see when the process started to trend in a bad direction.  I have seen it in a Emerson Delta V and I think I have also seen it in an ABB Freelance and XA system. Just hoping someone can point me in a direction.  Thank you. 

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Split from How to calculate arithmetic average of an analog input in the TIA V12.

AutoGen_5258601

I see this is a very old post but I'm hoping to revive it.  I am wanting a function that you can input a running time of a piece of equipment and the running average would be calculated to a maximum of X hrs. to help operators see when the process started to trend in a bad direction.  I have seen it in a Emerson Delta V and I think I have also seen it in an ABB Freelance and XA system. Just hoping someone can point me in a direction.  Thank you. 

My first impression, after you mentioned Delta V and Freelance, is that you selected wrong tool for the job. Theirs counterpart in Siemens world is ex. Simatic PCS and not TIA.

Anyway. Your description of functionality is, IMHO, not detailed enough to propose any solution I've met in TIA. Try to supply something more detailed.

In general running average calculation involves some circular buffer and simple arithmetics. But it seems like the functionality you described is a little bit more sophisticated than that.

Martins_Eng

Staff

There is a way to create a FB to calculate a 
sample average of an analog input , because I have a 
lot of ocilação this input, and want to calculate the 
media to reduce this fluctuation values.
Making the calculation .
(X1 X2 + X3 + ... + Xn ) / n

 Hi,

maybe instead of arithimetic average, you could use the first order filter. It is ready for use in TIA (toolbox, Technology, PID control, Auxiliary functions, filter_PT1). 

instead of using average you can make a filter (convert AI reading to REAL)

Filtered value must be STAT or DB or M (not temp)

Filtered_Value:=Factor*Raw_AI+(Factor-1.0)*Filtered_Value;

factor from 0 to 1 (0 = disabled; small = strong filter; 1 = no filter)

and call it at fixed intervals, for exampl every 100ms (or AI conversion time)

Hi,

I have not checked these blocks in detail, but maybe you can build something own out of these:

Library of general functions (LGF) for SIMATIC STEP 7 (TIA Portal) and SIMATIC S7-1200 / S7-1500

-> LGF_FloatingAverage (FB / V3.0.2)
"This function calculates a moving arithmetic mean value from REAL values. This
method can be used to smooth data series. The values can be read in cyclically or
triggered."

-> LGF_AverageAndDeviation (FC / V3.0.1)
"This function calculates the arithmetic mean and the standard deviation from a
series of numbers."

regards

sancruz