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SCL Integral example problem

Created by: kamy2019 at: 12/24/2019 4:10 AM (7 Replies)

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12/24/2019 4:10 AM	Rate (0)
kamy2019 Posts: 9 Rating: (0)	hi dears according to the link below and a PNG that i have attached https://support.industry.siemens.com/cs/ww/en/view/13406965 i can't understand the steps of programming and variables definition . is there anyone help me to understand fluencly this program? tnx in advanced ------------------------------------------------------------------------------------------ Split from SCL programming. Attachment integral.png (288 Downloads)
kamy2019 Posts: 9 Rating: (0)	Last edited by: Jen_Moderator at: 12/25/2019 12:51:28 New subject after splitting. Optimized link Last edited by: kamy2019 at: 12/29/2019 15:23:39
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12/30/2019 11:15 AM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 9/27/2023 Posts: 4273 Rating: (667)	Rewrite this code in text and add here, then I can think of.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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12/30/2019 10:09 PM	Rate (0)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/25/2023 Posts: 6822 Rating: (1349)	Hello , according to the link below and a PNG that i have attached https://support.industry.siemens.com/cs/ww/en/view/13406965 i can't understand the steps of programming and variables definition . is there anyone help me to understand fluencly this program? tnx in advanced The block is a bit difficult to analyze because of using SFC64 for time measurement. Mostly we use the time difference between to cyclic interrupts in CPU as Delta T for integral calculation.You can consider it constant and the user need to provide it as sample or cycle input like the one in FB41 as PID.Here , you don't need to provide Delta T because it is calculated internally. The other things that you need to know is the trapezoid areal calculation and you can google it. I summarized all important points in the following Youtube video , you need to test it online for more clues. I hope it helps, hdhosseini
	Demo Channel on Youtube
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2/4/2020 10:57 PM	Rate (0)
kamy2019 Posts: 9 Rating: (0)	thank you Jacek d need to be noted after i spent time to analyze the codes i could figure out what is going on but what , confuses me are lines which i have signed those with ????????? mark. VAR_OUTPUT OUT:REAL; RESET_ACTIVE:BOOL; END_VAR VAR OUT_LOW:REAL; LAST_IN:REAL; LAST_OUT:REAL; LAST_TIME:REAL; ACTUAL_TIME:REAL; X:REAL; N:INT; END_VAR //RESET OF VALUES RESET_ACTIVE:=RESET; IF RESET=TRUE THEN OUT:=0.0; OUT_LOW:=0.0; LAST_OUT:=0.0; LAST_TIME:=ACTUAL_TIME; ACTUAL_TIME:=TIME_TO_DINT(TIME_TCK())/1000.0; X:=0.0; N:=0; ELSIF ENABLE=FALSE THEN N:=0; ELSE //FIRST INTEGRAL CYCLUS IF N=0 THEN ACTUAL_TIME:=TIME_TO_DINT(TIME_TCK())/1000.0; LAST_TIME:=ACTUAL_TIME; LAST_IN:=IN; N:=1; ELSE // INPUT ACTUAL_TIME:=TIME_TO_DINT(TIME_TCK())/1000.0; //OVERFLOW CORRECTION IF ACTUAL_TIME<LAST_TIME THEN X:=(ACTUAL_TIME-LAST_TIME+2147483.647)(IN+LAST_IN)/2; ELSE X:=(ACTUAL_TIME-LAST_TIME)(IN+LAST_IN)/2; END_IF; LAST_TIME:=ACTUAL_TIME; LAST_IN:=IN; // INTEGRAL CALCULATION LAST_OUT:=OUT; OUT:= LAST_OUT+X; OUT_LOW:=(OUT-LAST_OUT)-X+OUT_LOW; //??????????? IF OUT_LOW<>0 THEN IF ABS(OUT/OUT_LOW)<10000000 THEN LAST_OUT:=OUT; OUT:=OUT-OUT_LOW; OUT_LOW:=(OUT-LAST_OUT)+OUT_LOW; //????????????? END_IF; END_IF; END_IF; END_FUNCTION_BLOCK as far as this line is always zero : OUT_LOW:=(OUT-LAST_OUT)-X+OUT_LOW; so what is the functionality of rest codes??? thank you so much
kamy2019 Posts: 9 Rating: (0)	Last edited by: kamy2019 at: 02/04/2020 23:08:36 Last edited by: kamy2019 at: 02/04/2020 23:09:18 Last edited by: kamy2019 at: 02/04/2020 23:09:51
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2/4/2020 11:08 PM	Rate (0)
kamy2019 Posts: 9 Rating: (0)	thank you too dear hdhosseini your video gave me a good view of understanding the codes related to N variable's functionality. in this project sampling time is extracted from SFC64 so with CPU's cycle time all the samples will be taken and question is this what if i want to limit my sampling time to OB35? i mean what will be changed in program's lines.is it enough to remove the codes related to ACTUAL_TIME:REAL; variable and let to FB to be called in each OB's cycle time?could you please guide me how to implement the codes and blocks? thank you so much
kamy2019 Posts: 9 Rating: (0)
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2/5/2020 8:42 AM	Rate (1)
hdhosseini Diamond Expert Joined: 1/28/2009 Last visit: 9/25/2023 Posts: 6822 Rating: (1349)	Your code is become drastically simpler.In line that X is calculated such as X:=(ACTUAL_TIME-LAST_TIME+2147483.647)(IN+LAST_IN)/2; simply substitute (ACTUAL_TIME-LAST_TIME+2147483.647) with a constant (CYCLE) sampling period known as input of FB. CYCLE(IN+LAST_IN)/2; Remove all unnecessary sections related to time measurement and test your program again.
	Demo Channel on Youtube
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This contribution was helpful to 1 thankful Users kamy2019

2/5/2020 8:46 AM	Rate (1)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 9/27/2023 Posts: 4273 Rating: (667)	kamy2019 as far as this line is always zero : OUT_LOW:=(OUT-LAST_OUT)-X+OUT_LOW; Actually it is not. Reason for this is finite resolution of floating point numbers. Have a look at Kahan summation algorithm.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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This contribution was helpful to 3 thankful Users hdhosseini kamy2019 crazyCow

2/6/2020 3:57 AM	Rate (0)
kamy2019 Posts: 9 Rating: (0)	dear jacek d; Actually it is not. Reason for this is finite resolution of floating point numbers. Have a look atKahan summation algorithm. i got it. so many thanks
kamy2019 Posts: 9 Rating: (0)
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This contribution was helpful to 1 thankful Users jacek d

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