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Basic of the SCL. SQRT and SQR

Created by: The_Beginner at: 9/4/2020 10:31 AM (7 Replies)

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9/4/2020 10:31 AM	Rate (0)
The_Beginner Posts: 11 Rating: (0)	Welcome everyone! I need help with basic comprehension of SCL. FUNCTION_BLOCK Funkcja VAR_INPUT a : INT //:=1; b : INT //:=4; C : INT //:=2; END_VAR VAR_TEMP delta : INT; mem1 : INT; mem2 : INT; pierdel : INT; END_VAR VAR_OUTPUT x1 : INT; x2 : INT; END_VAR a :=1; b :=4; c :=2; IF b <> 0 THEN delta := SQRT(b)-(4ac); END_IF; IF delta >0 THEN x1 := SQRT(delta); END_IF; END_FUNCTION_BLOCK Everytime i try to use one of SQRT or SQR function like in this case i got INVALID DATA TYPE. As far as i understand it has to be a numeric value so that it must be int! For comparision i have a book in which i have this code: Examples: Reactivejpower := Voltage * Current * SIN(phi); Volume := SQR(Radius) * Level * PI; c := SQRT(SQR(a) + SQR(b)); so it;s simple, but nevertheless i CANT compile it! if someone can help me, please do so. Best regards!
The_Beginner Posts: 11 Rating: (0)
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9/4/2020 11:32 AM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 6/5/2023 Posts: 4179 Rating: (644)	We need used software and hardware names/versions first.
	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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9/4/2020 12:00 PM	Rate (0)
The_Beginner Posts: 11 Rating: (0)	Its a step 7 software with a scl editor. Version 5.6 +SP1. Running on a 319F-3 PLCSIM.
The_Beginner Posts: 11 Rating: (0)	Last edited by: The_Beginner at: 09/04/2020 12:00:38
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9/4/2020 12:31 PM	Rate (0)
qwazee Platinum Member Joined: 3/30/2020 Last visit: 6/5/2023 Posts: 3548 Rating: (791)	Hello. The_Beginner <snip> Everytime i try to use one of SQRT or SQR function like in this case i got INVALID DATA TYPE. As far as i understand it has to be a numeric value so that it must be int! For comparision i have a book in which i have this code: </snip> Use REAL instead of INT. ..and 4 is a constant INT while 4.0 is a constant REAL. The commands you wish to use applies to REAL numbers. BR
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9/4/2020 12:37 PM	Rate (0)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 6/5/2023 Posts: 12034 Rating: (2595)	Hello Beginner; S7 error messages are generally quite literal, when you are told that you are not using the correct data type look in the Step 7 online help or the manuals at what type is expected. In the case of SQRT, inputs and output values to the function are expected as REAL (IEEE 751 floating-point format). Open the SCL programming for S7-300 and S7-400 manual: https://support.industry.siemens.com/cs/ww/en/view/1137188 Hope this helps, Daniel Chartier Attachment Screenshot_20200904-063020_Drive.jpg (142 Downloads)

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9/4/2020 12:59 PM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 6/5/2023 Posts: 4179 Rating: (644)	dchartier S7 error messages are generally quite literal, when you are told that you are not using the correct data type look in the Step 7 online help or the manuals at what type is expected. Frankly saying, he probably did it. The manuals, page 18-9: The data type ANY_NUM stands for INT, DINT or REAL. General functions are for calculating the absolute amount, the square or the square root of an amount. Table 18-5 General Functions <snip> Note that input parameters of the type ANY_NUM are converted internally into real variables.
	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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9/4/2020 4:37 PM	Rate (1)
dchartier Grandmaster Joined: 9/27/2006 Last visit: 6/5/2023 Posts: 12034 Rating: (2595)	Hello Jacek; I admit I was very surprised to find the ANY_NUM designation for the inputs of the SQRT and SQR you pointed to. I had not realized that these SCL functions did the type casting of input values to REAL values by itself. However, to get back to Beginner's problem, the output value of the SQRT function must be a REAL (your table gives no alternate possibility for the function value), and the variable x1 has been cast as INT. That might be his issue, as x1 takes the retiurn value of SQRT. Hope this helps, Daniel Chartier

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9/23/2020 8:07 AM	Rate (0)
The_Beginner Posts: 11 Rating: (0)	OK. Indeed it was var type issue. Everything work with REAL. Thanks to all who put an effort in helping me. Best regards!
The_Beginner Posts: 11 Rating: (0)
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This contribution was helpful to 1 thankful Users qwazee

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